Waste LCA and the future

Life cycle assessment (LCA) models quantifying the environmental aspects of waste management have become an integral part of waste management decision-making over the last two decades and have provided ample knowledge on both environmental benefits and drawbacks in the way we handle waste. Waste management and LCA modelling of waste management systems will soon be challenged by profound changes necessary in our societies and sectors to meet sustainable development goals. Foreseen changes in energy, material, and nutrient provision will directly and indirectly affect waste management in terms of its operation and goals. This study reflects on anticipated changes in society and industrial sectors and how these changes may affect waste management and LCA modelling of waste management systems in terms of waste input, the modelling of technologies and systems and exchanges of energy, materials, and nutrients, as well as how it may affect impact assessment and the interpretation of results. The study provides practical recommendations for LCA modelling of future waste management systems, which will hopefully lead to robust assessments that can support decision-making in an evolving society subject to great changes.

Comparing Outcomes of Bicruciate-Stabilized and Cruciate-Retaining Total Knee Arthroplasty

Background

Bicruciate-stabilized (BCS) total knee arthroplasty (TKA) aims to restore normal kinematics by replicating the function of both cruciate ligaments. Conventional cruciate-retaining (CR) design in TKA has shown previous clinical success with lower complication rates. This study compared the patient-reported outcomes between the BCS and CR TKA designs.

Methods

This retrospective study examined patients who underwent primary TKA using a CR or a BCS implant. Patient demographics, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR), and Forgotten Joint Score (FJS) were compared between two cohorts. Patient-reported outcome measures were analyzed using independent samples t-tests.

Results

There were no significant preoperative demographic differences between groups. The CR cohort (n = 756) had significantly higher average KOOS, JR Scores compared to the BCS cohort (n = 652) at 3 months (59.7 ± 3.8 vs. 53.0 ± 3.9, p < 0.001) and 2 years (62.6 ± 8.0 vs. 53.8 ± 6.7, p = 0.001) after TKA. Within the cohort, KOOS, JR delta differences were not significant for CR when comparing patient scores 3 months to 1 year after surgery. Meanwhile, the BCS patients did show significant delta improvement (4.1 ± 1.9, p = 0.030) when compared 3 months to 1 year after surgery. One year postoperatively, the BCS cohort (n = 134) showed a significantly higher average FJS score (49.5 ± 31.4, vs. 36.8 ± 28.5, p = 0.028) than the CR cohort (n = 203). Both cohorts displayed a significant difference in delta improvements within their respective cohort when measuring FJS from 3 months to 1 year, 2 years, and 3 years after surgery.

Conclusions

The CR cohort performed better on average, compared to the BCS cohort in measures of KOOS, JR scores at the 2-year follow-up. The BCS cohort performed marginally better regarding FJS only at 1-year follow-up.

Does the Primary Surgical Approach Matter When Choosing the Approach for Revision Total Hip Arthroplasty?

BACKGROUND

Multiple surgical approaches are used for primary total hip arthroplasty (pTHA) and revision total hip arthroplasty (rTHA). This study sought to investigate prevalence of discordance of pTHA and rTHA surgical approaches and to evaluate how approach concordance impacts postoperative outcomes.

METHODS

A retrospective review of patients who underwent rTHA from 2000 to 2021 was conducted at 3 large urban academic centers. Patients who had minimum 1-year follow-up post-rTHA were included and grouped based on whether they received pTHA via a posterior (PA), direct anterior (DA), or laterally based (DL) approach, and by concordance of index rTHA approach with their pTHA approach. Of the 917 patients studied, 839 (91.5%) were included in the concordant cohort and 78 (8.5%) in the discordant cohort. Patient demographics, operative characteristics, and postoperative outcomes were compared.

RESULTS

Discordance was most prevalent in the DA-pTHA subset (29.5%), compared to the DL-pTHA subset (14.7%) or PA-pTHA subset (3.7%). Discordance varied significantly between primary approaches among all revisions, with DA-pTHA patients having the highest discordance rate for patients revised for aseptic loosening (46.3%, P < .001), fracture (22.2%, P < .001), and dislocation (33.3%, P < .001). There were no differences between groups in dislocation rate, re-revision for infection, or re-revision for fracture.

CONCLUSION

The results of this multicenter study showed patients who received pTHA via the DA were more likely to receive rTHA via a discordant approach compared to other primary approaches. Since approach concordance did not impact dislocation, infection, or fracture rates after rTHA, surgeons can feel reassured using a separate approach for rTHA.

LEVEL III EVIDENCE

Retrospective Cohort Study.

The Impact of Surgeon Proficiency in Non-English-Speaking Patients' Primary Language on Outcomes After Total Joint Arthroplasty

Non-English-speaking patients face increased communication barriers when undergoing total joint arthroplasty (TJA). Surgeons may learn or have proficiency in languages spoken among their patients to improve communication. This study investigated the effect of surgeon-patient language concordance on outcomes after TJA. We conducted a single-institution, retrospective review of patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) whose preferred language was not English. Patients were stratified based on whether their surgeon spoke their preferred language (language concordant [LC]) or not (language discordant [LD]). Baseline characteristics, length of stay, discharge disposition, revision rate, readmission rate, and patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score for Joint Replacement [KOOS, JR], Hip disability and Osteoarthritis Outcome Score for Joint Replacement [HOOS, JR], and Patient-Reported Outcomes Measurement Information System [PROMIS]) were compared. A total of 3390 patients met inclusion criteria, with 855 receiving THA and 2535 receiving TKA. Among patients receiving THA, 440 (51.5%) saw a LC provider and 415 (48.5%) saw a LD provider. Those in the LC group had higher HOOS, JR scores at 1 year postoperatively (67.4 vs 49.3, P=.003) and were more likely to be discharged home (77.5% vs 69.9%, P=.013). Among patients receiving TKA, 1051 (41.5%) received LC care, whereas 1484 (58.5%) received LD care. There were no differences in outcome between the LC and LD TKA groups. Patients receiving THA with surgeons who spoke their language had improved patient-reported outcomes and were more commonly discharged home after surgery. Language concordance did not change outcomes in TKA. Optimizing language concordance for patients receiving TJA may improve postoperative outcomes. [Orthopedics. 2023;46(6):334-339.].

The Impact of Hospital Exposures Prior to Total Knee Arthroplasty on Postoperative Outcomes

Background

Total knee arthroplasty (TKA) procedures are expected to grow exponentially in the upcoming years, highlighting the importance of identifying preoperative risk factors that predispose patients to poor outcomes. The present study sought to determine if preoperative healthcare events (PHEs) influenced outcomes following TKA.

Methods

This was a retrospective review of all patients who underwent TKA at a single institution from June 2011 to April 2022. Patients who had a PHE within 90 days of surgery, defined as an emergency department visit or hospital admission, were compared to patients with no history of PHE. Patients who underwent revision, nonelective, and/or bilateral TKA were excluded. Chi-squared analysis and independent sample t-tests were used to determine significant differences between demographic variables. All significant covariates were included in binary logistic regressions used to predict discharge disposition, 90-day readmission, and 1-year revision.

Results

Of the 10,869 patients who underwent TKA, 265 had ≥1 PHE. Patients who had a PHE were significantly more likely to require facility discharge (odds ratio [OR]: 1.662; P = .001) than patients who did not have a PHE. Any PHE predisposed patients to significantly higher 90-day readmission rates (OR: 2.173; P = .002). Patients with ≥2 PHEs were at a significantly higher risk of 1-year revision (OR: 5.870; P = .004) compared to patients without a PHE.

Conclusions

Our results demonstrate that PHEs put patients at significantly greater risk of facility discharge, 90-day readmission, and 1-year revision. Moving forward, consideration of elective surgery scheduling in the context of a recent PHE may lead to improved postoperative outcomes.

Level III Evidence

Retrospective Cohort Study.

Perioperative Outcomes in Total Knee Arthroplasty for Non-English Speakers

BACKGROUND

Many studies have demonstrated that in patients whose primary language is not English, outcomes after an orthopaedic surgery are worse compared to primary English speakers. The goal of this study was to compare perioperative outcomes in patients undergoing total knee arthroplasty (TKA) who prefer English as their first language versus those who prefer a different language.

METHODS

We retrospectively reviewed all patients who underwent primary TKA from May 2012 to July 2021. Patients were separated into two groups based on whether English was their preferred primary language (PPL). Of the 13,447 patients who underwent primary TKA, 11,290 reported English as their PPL, and 2,157 preferred a language other than English. Patients whose PPL was not English were further stratified based on whether they requested interpreter services. Multiple regression analyses were performed to determine the significance of perioperative outcomes while controlling for demographic differences.

RESULTS

Our analysis found that non-English PPL patients had significantly lower rates of readmission (P = .040), overall revision (P = .028), and manipulation under anesthesia (MUA; P = .025) within 90 days postoperatively. Sub analyses of the non-English PPL group showed that those who requested interpreter services had significantly lower 1-year revision (P < .001) and overall MUA (P = .049) rates.

CONCLUSION

Our results demonstrate that TKA patients who communicated in English without an interpreter were significantly more likely to undergo revision, readmission, and MUA. These findings may suggest that language barriers may make it more difficult to identify postoperative problems or concerns in non-English speakers, which may limit appropriate postoperative care.

LEVEL III EVIDENCE

Retrospective Cohort Study.

How Does Surgical Approach Affect Characteristics of Dislocation After Primary Total Hip Arthroplasty?

BACKGROUND

Concerns have been voiced regarding how surgical approach impacts risk of dislocation after total hip arthroplasty (THA). This study investigated how surgical approach impacts rate, direction, and timing of dislocations following THA.

METHODS

We conducted a retrospective review of 13,335 primary THAs from 2011 to 2020 and identified 118 patients with prosthetic hip dislocation. Patients were stratified into cohorts by surgical approach used during primary THA. Patient demographics, index THA acetabular cup positioning, number, direction, timing of dislocations, and subsequent revisions were collected.

RESULTS

Dislocation rate differed significantly between posterior approach (PA), direct anterior approach (DAA), and laterally-based approach (LA) (1.1 versus 0.7% versus 0.5%, P = .026). Rate of hips dislocating anteriorly was lowest in the PA group (19.2%) compared to LA (50.0%) and DAA groups (38.2%, P = .044). There was no difference in rate of hips dislocating posteriorly (P = .159) or multidirectional (P = .508) instability; notably 58.8% of dislocations in the DAA cohort occurred posteriorly. There were no differences in dislocation timing or revision rate. Acetabular anteversion was highest in the PA cohort compared to DAA and LA (21.5 versus 19.2 versus 11.7 degrees, P = .049).

CONCLUSION

After THA, patients in the PA group had a slightly higher dislocation rate compared to the DAA and LA groups. The PA group had a lower rate of anterior dislocation and nearly 60% of DAA dislocations occurred posteriorly. However, with no differences in other parameters including revision rates or timing, our data suggests surgical approach may impact dislocation characteristics to a lesser degree than previous studies have suggested.

Is It Necessary to Obtain Lateral Pelvic Radiographs in Flexed Seated Position for Preoperative Total Hip Arthroplasty Planning?

Background

Many of the current total hip arthroplasty (THA) planning tools only consider sagittal pelvic tilt in the standing and relaxed sitting positions. Considering that the risk of postoperative dislocation is higher when bending forward or in sit-to-stand move, sagittal pelvic tilt in the flexed seated position may be more relevant for preoperative planning. We hypothesized that there was a significant difference in sagittal pelvic tilt between the relaxed sitting and flexed seated positions as measured by the sacral slope in preoperative and postoperative full-body radiographs.

Methods

This was a multicenter retrospective analysis of the preoperative and postoperative simultaneous biplanar full-body radiographs of 93 primary THA patients in standing, relaxed sitting, and flexed seated positions. The sagittal pelvic tilt was measured using the sacral slope relative to the horizontal line.

Results

The mean difference between the preoperative sacral slope in the relaxed sitting position and the flexed seated position was 11.3° (-13° to 43°) (P < .0001). This difference was >10° in 52 patients (56%) and >20° in 18 patients (19.4%). The mean difference between the postoperative sacral slope in a relaxed sitting position and the sacral slope in a flexed seated position was 11.3° (P < .0001). This difference was >10° in 51 patients (54.9%) and >30° in 14 patients (15.1%) postoperatively.

Conclusions

There was a significant difference in sagittal pelvic tilt between the relaxed and flexed seated positions. A flexed seated view provides valuable information that might be more relevant for preoperative THA planning in order to prevent postoperative THA instability.

The Current Proposed Total Hip Arthroplasty Surgical Planning Guidelines Based on Classification of Spine Stiffness May be Flawed Due to Incorrect Assumptions

BACKGROUND

The available classifications and preoperative planning tools for total hip arthroplasty assume that: 1) there is no variation in the sagittal pelvic tilt (SPT) if the radiographs are repeated, and 2) there is no significant change in the postoperative SPT postoperatively. We hypothesized that there would be significant differences in postoperative SPT tilt as measured by the sacral slope, thus rendering the current classifications and tools flawed.

METHODS

This study was a multicenter, retrospective analysis of preoperative and postoperative (1.5-6 months) full-body imaging of 237 primary total hip arthroplasty (standing and sitting positions). Patients were categorized as 1) stiff spine (standing sacral slope sitting sacral slope < 10°) and 2) normal spine (standing sacral slope-sitting sacral slope ≥ 10°). Results were compared using the paired t-test. The posthoc power analysis showed a power of 0.99.

RESULTS

The difference in mean standing and sitting sacral slope between the preoperative and postoperative measurements was 1°. However, in standing position, this difference was more than 10° in 14.4% of patients. In the sitting position, this difference was more than 10° in 34.2% of patients and more than 20° in 9.8% of patients. Postoperatively, 32.5% of patients switched groups based on the classification, which rendered the preoperative planning suggested by the current classifications flawed.

CONCLUSION

Current preoperative planning and classifications are based on a single acquisition of preoperative radiographs without the incorporation of possible postoperative changes in SPT. Validated classifications and planning tools should incorporate repeated measurements to determine the mean and variance in SPT and consider the significant postoperative changes in SPT.

Mini-review of inventory data for the dewatering and drying of sewage sludge

Technological comparison and system modelling of sewage sludge treatment are important in terms of sustainable development and climate change mitigation. Dewatering and drying are important processes for reducing volume for transportation and often a requirement for further sludge treatment. Inventory data on mass transfers and material and energy consumptions are therefore crucial in improving and understanding sludge management systems. Reviewing the scientific literature (2003-2021) revealed 55 and 21 datasets on dewatering and drying of sewage sludge, respectively. The scarcity of data did not allow for identifying detailed relationships between inputs and outputs for the technologies, but the reviewed data can serve as the first port of call when planning sludge management. The average total solid (TS) content obtained was statistically different for mechanical dewatering (MDW), deep dewatering, bio-drying (BDR) and thermal drying (TDR). Loss of volatile solids (VS) during dewatering is barely described, but a substantial VS loss was observed for TDR (8%) and BDR (27%). The use of chemical agents in MDW showed typical values of 5-15 g kg^-1 TS. The use of energy is low for MDW (average of 0.12 and 0.26 kWh kg^-1 TS for raw and digested sludges, respectively) but substantially higher for TDR (average of 3.8 kWh kg^-1 TS). The justified inventory data for sludge dewatering and drying provide essential support to system modelling and technological comparison in future studies, but additional data from full-scale plants on energy consumption and the composition of removed water are strongly requested to improve the inventory.

Climate change impacts of conventional sewage sludge treatment and disposal

Sewage sludge (SS) management remains a challenge across the world. We quantified the potential climate change impacts of eight conventional technology configurations (TCs) for SS treatment and disposal by considering four different energy exchanges and using a life cycle assessment (LCA) model that employed uncertainty distributions for 104 model parameters. All TCs showed large climate change loads and savings (net values ranging from 123 to 1148 kg CO₂-eq/t TS) when the energy exchange was with a fossil-based energy system, whereas loads and savings were approximately three times lower when the energy exchange was with a renewable energy system. Uncertainty associated with the climate change results was more than 100% with fossil-energy exchange and low TS content of SS but was lower for renewable energy. Landfilling had the greatest climate change impact, while thermal drying with incineration had the highest probability of providing better climate change performance than other TCs. The global sensitivity analysis identified nine critical technological parameters. Many of them can be easily measured for relevant SS and technology levels to improve specific estimates of climate change impact. When all scenarios were optimized to the 20% best cases, thermal drying with incineration outperformed the other TCs. This paper contributes to better quantifying the climate change impacts of different technologies used for sludge treatment given changing energy systems and identifies crucial parameters for further technological development.

Mini-review of sewage sludge parameters related to system modelling

System modelling of sewage sludge (SS) treatment attracts a growing interest for better comparison and optimisation of technologies. However, SS parameters need to be generalised to be used in holistic assessments, since scattered data may inhibit the development and interpretation of system models. A review of the literature on SS parameters relevant to modelling SS treatment systems revealed 208 datasets published in 162 publicly available scientific papers. We treated thickened and dewatered sludge in the same data analysis, but in some cases, this was an incorrect assumption. The compositional data showed significant variations, but most of the data subscribed to a lognormal distribution, albeit with varying levels of significance. On average, the thickened sludge contained 3.3 ± 1.7% total solid (TS), and the dewatered sludge contained 21.0 ± 6.7% TS. For the combined data, the average Ash content was 32.4 ± 11.8% of TS. Other characteristic parameters were the lower heating value (LHV) of 22.1 ± 2.1 MJ kg^-1 volatile solid (VS) and the biochemical methane potential (BMP) of 0.25 ± 0.11 m³ CH₄ kg^-1 VS. Fertiliser-related elements were on average 53.3 ± 9.3% C in VS, 6.8 ± 2.2% N in VS, 6.7 ± 2.4% P in Ash and 1.7 ± 1.3% K in Ash. The data reviewed herein provide a good basis for assessing the generality of individual SS data and for selecting key parameters for modelling SS treatment systems. However, the review reveals a need for the better characterisation of SS in the future.

Opioid Use during Hospitalization following Total Knee Arthroplasty: Trends in Consumption from 2016 to 2021

INTRODUCTION

In response to physician and patient concerns, many institutions have adopted protocols aimed at reducing postoperative opioid consumption after total knee arthroplasty (TKA). Thus, this study sought to examine how consumption of opioids has changed following TKA in the past six years.

METHODS

We conducted a retrospective review of all 10,072 patients who received primary TKA at our institution from January 2016 to April 2021. We collected baseline demographic data including patient age, sex, race, body mass index (BMI), American Society of Anesthesiologist (ASA) classification, as well as dosage and type of opioid medication prescribed on each postoperative day while the patient was hospitalized following TKA. This data was converted to milligram morphine equivalents (MME) per day hospitalized to compare rates of opioid use over time.

RESULTS

Our analysis found the greatest daily opioid use was in 2016 (43.2±68.6 MME/day) and the least was in 2021 (15.0±29.2 MME/day). Linear regression analyses found a significant linear downward trend in postoperative opioid consumption over time, with a decrease of 5.55 MME per day per year (Adjusted R-squared: 0.982, P<0.001). The highest visual analog scale (VAS) score was 4.45 in 2016 and the lowest was 3.79 in 2021 (P<0.001).

CONCLUSION

Opioid reducing protocols have been implemented for patients recovering from primary TKA in an effort to decrease reliance on opioids for postoperative pain control. The results of this study demonstrate that such protocols have been successful in reducing overall opioid use during hospitalization following TKA.

Impact of the COVID-19 Pandemic on Patient Satisfaction After Total Joint Arthroplasty

The coronavirus disease 2019 (COVID-19) pandemic impacted the inpatient experience before and after total joint arthroplasty (TJA). This study aimed to examine how these changes affected patient satisfaction following TJA as recorded by Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) postdischarge surveys and comments at 2 large academic institutions. A retrospective review identified patients who completed HCAHPS surveys following primary and revision TJA at 2 academic institutions: 1 in a predominately rural southern state (Institution A) and 1 in a northeastern metropolitan city (Institution B). Patients were grouped by discharge date: pre-COVID-19 (April 1, 2019, to October 31, 2019) or COVID-19 affected (April 1, 2020, to October 31, 2020). Differences in demographics, survey responses, and comment sentiments and themes were collected and evaluated. The number of HCAHPS surveys completed increased between periods at Institution A but decreased at Institution B (Institution A, 61 vs 103; Institution B, 524 vs 296). Rates of top-box survey responses remained the same across the 2 periods. The number of comments decreased at Institution B (1977 vs 1012) but increased at Institution A (55 vs 88). During the COVID-19-affected period, there was a significant increase in the negative comment rate from Institution B (11.6% vs 14.8%, P=.013) and a significant decrease in the positive comment rate from Institution A (70.9% vs 44.3%, P<.001). There was an increase in negative patient sentiments following TJA during the COVID-19 pandemic as seen in qualitative comments but not quantitative responses. This suggests that certain aspects of the TJA patient experience were impacted by COVID-19. [Orthopedics. 2023;46(2):e105-e110.].

Total hip arthroplasty for hip fractures in patients older than 80 years of age: a retrospective matched cohort study

INTRODUCTION

Increasing age and hip fractures are considered risk factors for post-operative complications in total hip arthroplasty (THA). Consequently, older adults undergoing THA due to hip fracture may have different outcomes and require additional healthcare resources than younger patients. This study aimed to identify the influence of age on discharge disposition and 90-day outcomes of THA performed for hip fractures in patients ≥ 80 years to those aged < 80.

MATERIALS AND METHODS

A retrospective review of 344 patients who underwent primary THA for hip fracture from 2011 to 2021 was conducted. Patients ≥ 80 years old were propensity-matched to a control group < 80 years old. Patient demographics, length of stay (LOS), discharge disposition, and 90-day post-operative outcomes were collected and assessed using Chi-square and independent sample t tests.

RESULTS

A total of 110 patients remained for matched comparison after propensity matching, and the average age in the younger cohort (YC, n = 55) was 67.69 ± 10.48, while the average age in the older cohort (OC, n = 55) was 85.12 ± 4.77 (p ≤ 0.001). Discharge disposition differed between the cohorts (p = 0.005), with the YC being more likely to be discharged home (52.7% vs. 27.3%) or to an acute rehabilitation center (23.6% vs. 16.4%) and less likely to be discharged to a skilled nursing facility (21.8% vs. 54.5%). 90-day revision (3.6% vs. 1.8%; p = 0.558), 90-day readmission (10.9% vs. 14.5%; p = 0.567), 90-day complications (p = 0.626), and 90-day mortality rates (1.8% vs 1.8%; p = 1.000) did not differ significantly between cohorts.

CONCLUSION

While older patients were more likely to require a higher level of post-hospital care, outcomes and perioperative complication rates were not significantly different compared to a younger patient cohort. Payors need to consider patients' age in future payment models, as discharge disposition comprises a large percentage of post-discharge expenses.

LEVEL OF EVIDENCE

Level III, Retrospective Cohort Study.

Impact of revision TKA indications on resource utilization

BACKGROUND

Indications for surgery may impact resource utilization in aseptic revision total knee arthroplasty (rTKA), and understanding these relationships would facilitate risk-stratification preoperatively. The purpose of this study was to investigate the impact of rTKA indications on readmission, reoperation, length of stay (LOS), and cost.

METHODS

We reviewed all 962 patients who underwent aseptic rTKA at an academic orthopedic specialty hospital between June 2011-April 2020 with at least 90 days of follow-up. Patients were categorized based on their indication for aseptic rTKA as listed in the operative report. Demographics, surgical factors, LOS, readmission, reoperation and cost were compared between cohorts.

RESULTS

There were significant differences in operative time among cohorts (p < 0.001), highest among the periprosthetic fracture group (164.2 ± 59.8 min). Reoperation rate was greatest in the extensor mechanism disruption cohort (50.0 %, p = 0.009). Total cost differed significantly among groups (p < 0.001), which was highest among the implant failure cohort (134.6 % of mean) and lowest for component malpositioning cohort (90.2 % of mean). Similarly, there were significant differences in direct cost (p < 0.001) which was highest in the periprosthetic fracture cohort (138.5 % of mean), and lowest in the implant failure cohort (90.5 % of mean). There were no differences in discharge disposition, or number of re-revisions among all groups.

CONCLUSIONS

Operative time, components revised, LOS, readmissions, reoperation rate, total cost and direct cost following aseptic rTKA varied significantly between different revision indications. These differences should be noted for preoperative planning, resource allocation, scheduling, and risk-stratification.

LEVEL OF EVIDENCE

III, retrospective observational analysis.

Life cycle assessment of alternative biogas utilisations, including carbon capture and storage or utilisation

Biogas from anaerobic digestion is an important renewable energy source. Combining its utilisation with carbon capture and storage (CCS) or carbon capture and utilisation (CCU) may improve climate change performance. This study uses life cycle assessment to evaluate the environmental impacts of 17 biogas management technology configurations (TCs). The technologies include biogas combustion, upgrading to natural gas quality, CCS, direct utilisation of CO₂ and methanation. The focus is mainly on energy balances and climate change impacts, and the results are subjected to sensitivity-, uncertainty-, and energy system analysis. The TCs with CCS and CCU provide the largest climate change savings (-1400 to - 2100 kg CO₂-eq/1000 Nm³ biogas). Specifically, the methanation TCs provide the highest savings, but they also depend strongly on the energy sources. When combustion and upgrading TCs are amended with CCS, the resulting climate change savings are robust across the energy systems. The biogas upgrading TCs exhibit substantial climate change savings, mainly due to the natural gas substitution. Combustion TCs without CCS have the lowest climate change savings and the highest quantified uncertainties. The biogas upgrading TCs with storage or direct utilisation of CO₂ provide a good compromise between climate change savings and energy recovery. In the remaining impact categories, the CCU TCs generally perform best, followed by the upgrading TCs and finally, the combustion TCs. The CCS TCs consistently perform worse than their counterparts without CCS, opposite to the climate change results. Overall, amending biogas utilisation with CCS or CCU can contribute to climate change mitigation.

Review of inventory data for the biological treatment of sewage sludge

The biological treatment of municipal sewage sludge, including anaerobic digestion and composting, was reviewed with the purpose of establishing inventory data to address all the inputs and outputs related to sludge treatment. We identified 193 scientific papers, resulting in 64 datasets on anaerobic digestion and 35 datasets on composting. For anaerobic digestion, biogas production varied significantly (up to a factor of four) depending on the sludge. A useful correlation was identified between the amount of methane produced and the degradation of volatile solids. According to statistical tests, no significant differences were found in biogas production for mesophilic and thermophilic digesters. In addition, methane content varied significantly, and very few data were available for digestate composition or for energy consumption and recovery. For composting, accurate estimates relating to the degradation of sewage sludge could not be made, since organic bulking materials were part of the final composted product. Data on emissions to air are currently scarce, which points to the need for more published information. The inventory data evaluated herein are useful in the feasibility assessment of the biological treatment of sewage sludge, for comparing technologies, for example in LCA studies and as a basis for evaluating the performance of a specific biological sludge treatment plant. However, a great deal of the reviewed data originated from laboratory and pilot-scale studies, and so there is a need for more complete datasets on the performance of full-scale technologies, in order to establish full inventories and identify differences in technologies and operational conditions.

Hospital Revenue, Cost, and Contribution Margin in Inpatient Versus Outpatient Primary Total Joint Arthroplasty

BACKGROUND

Removal of primary total knee arthroplasty (TKA) and primary total hip arthroplasty (THA) from the inpatient-only list has financial implications for both patients and institutions. The aim of this study was to evaluate and compare financial parameters between patients designated for inpatient versus outpatient total joint arthroplasty.

METHODS

We reviewed all patients who underwent TKA or THA after these procedures were removed from the inpatient-only list. Patients were statistical significance into cohorts based on inpatient or outpatient status, procedure type, and insurance type. This included 5,284 patients, of which 4,279 were designated inpatient while 1,005 were designated outpatient. Patient demographic, perioperative, and financial data including per patient revenues, total and direct costs, and contribution margins (CMs) were collected. Data were compared using t-tests and Chi-squared tests.

RESULTS

Among Medicare patients receiving THA, CM was 89.1% lower for the inpatient cohort when compared to outpatient (P < .001), although there was no statistical significance difference between cohorts for TKA (P = .501). Among patients covered by Medicaid or Government-managed plans, CM was 120.8% higher for inpatients receiving THA (P < .001) when compared to outpatients and 136.3% higher for inpatients receiving TKA (P < .001).

CONCLUSION

Our analyses showed that recent costs associated with inpatient stay inconsistently match or outpace additional revenue, causing CM to vary drastically depending on insurance and procedure type. For Medicare patients receiving THA, inpatient surgery is financially disincentivized leaving this vulnerable patient population at a risk of losing access to care.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Impact of Indication for Revision THA on Resource Utilization

BACKGROUND

Demographic variables play an important role in outcomes following revision total hip arthroplasty (rTHA). Surgical and in-patient variables as well as outcomes vary between indications for rTHA. The purpose of this study was to investigate the impact of the indication for the rTHA on costs and postoperative outcomes.

METHODS

This retrospective cohort analysis investigated all patients who underwent unilateral, aseptic rTHA at an academic orthopaedic specialty hospital who had at least 1-year postoperative follow-up. In total, 654 patients were evaluated and categorized based on their indication for aseptic rTHA. Demographics, direct and total procedure costs, surgical factors, postoperative outcomes, and re-revision rates were collected and compared between indications.

RESULTS

Younger patients had the greatest leg length discrepancy (LLD) and older patients had the highest incidence of periprosthetic fracture (PPF) (P = .001). The greatest proportion of full revisions were found for LLD (16.7%) and head/polyethylene liner-only revisions for metallosis/adverse tissue reaction (100%). Operative time was significantly longest for LLD revisions and shortest for metallosis/adverse tissue reaction revisions (P < .001). Length of stay was longest for periprosthetic fracture and shortest for LLD and stiffness/heterotopic ossification (P < .001). Re-revision rate was greatest for implant failure and lowest for LLD. Total cost was highest for PPF (148.9%) and lowest for polyethylene liner wear (87.7%).

CONCLUSIONS

Patients undergoing rTHA for indications such as PPF and aseptic loosening were associated with longer operative times, length of stay and higher total and direct costs. Therefore, they may need increased perioperative attention with respect to resource utilization, risk stratification, surgical planning, and cost-reducing measures.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Trends in Revenue, Cost, and Contribution Margin for Total Joint Arthroplasty 2011-2021

BACKGROUND

Regulatory change has created a growing demand to decrease the hospital costs associated with primary total joint arthroplasty (TJA). Concurrently, the removal of lower extremity TJA from the in-patient only list has affected hospital reimbursement. The purpose of this study is to investigate trends in hospital revenue versus costs in primary TJA.

METHODS

We retrospectively reviewed all patients who underwent primary TJA from June 2011 to May 2021 at our institution. Patient demographics, revenue, total cost, direct cost, and contribution margin were collected. Changes over time as a percentage of 2011 numbers were analyzed. Linear regression analysis was used to determine overall trend significance and develop projection models.

RESULTS

Total knee arthroplasty (TKA) insured by government-managed/Medicaid (GMM) plans showed a significant upward trend (P = .013) in total costs. Direct costs of TKA across all insurance providers (P = .001 and P < .001) and total hip arthroplasty (THA) for Medicare (P = .009) and GMM (P = .001) plans demonstrated significant upward trends. Despite this, 2011-2021 modeling found no significant change in contribution margin for TKA and THA covered under all insurance plans. However, models based on 2018-2021 financial data demonstrated a significant downward trend in contribution margin across Medicare (P < .001) and GMM (P < .001) insurers for both TKA and THA.

CONCLUSION

Physician-led innovation in cost-saving strategies has maintained contribution margin over the past decade. However, the increase in direct costs seen over the past few years could lead to negative contribution margins over time, if further efficiency and cost-saving measures are not developed.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Climate Change Impact of the Development in Household Waste Management in China

The potential climate change impacts of the development in Chinese household waste management, with less landfilling, more incineration with energy recovery, and source-separated food waste treated in biorefineries, were assessed through a life cycle assessment. When the waste management system interacts with a fossil-based energy system, landfilling produces a load of 144 kg CO₂-eq/ton wet waste, while incineration shows a saving of 36 kg CO₂-eq/ton wet waste. The introduction of food waste source separation lowers climate change impacts by an additional 33 kg CO₂-eq/ton at a 60% sorting efficiency. As the Chinese energy system lowers its climate change impact over the next 30 years, energy recovery from waste treatment will change its relative contribution to climate change. In nonfossil energy systems, landfilling is estimated to have a climate change load of 180-240 kg CO₂-eq/ton wet waste, while incineration, including combinations with the source-separation of food waste, will have a load of 310-540 kg CO₂-eq/ton wet waste. These large intervals are due to waste composition uncertainty. However, considering a 20 year CH₄ characterization factor representing a shorter time perspective, the impacts from landfilling are more dramatic due to the large methane release. This significant climate change impact calls for an increased focus on the developments in Chinese household waste management. The key issues identified may also apply to other countries.

Review of inventory data for the thermal treatment of sewage sludge

The thermal treatment of sewage sludge has gained much interest in recent years, as exemplified by the 269 papers found in the scientific literature for the period 2010-2021. We identified 140 datasets in 57 papers presenting inventory data related to mass flows, energy and emissions for the incineration, gasification and pyrolysis of sewage sludge. Sewage sludge incineration (excess oxygen, 850-950 ℃) is an established technology; however, data on flue gas cleaning and air emissions are scarce. The recovery of energy is close to the amount of energy used for incinerating dried sludge (0.2 kWh/kg TS), while dewatered sludge incineration uses more energy (1-2 kWh/kg TS) than what can be recovered. Sewage sludge gasification (limited oxygen, 650-950 ℃) is an experimental technology with four outputs (kg/kg sludge TS): char 0.43, tar 0.02, fly ash 0.06 and syngas 0.53. The data vary significantly in this regard, suggesting than many factors affect the performance of the gasification process. Sewage sludge pyrolysis (no oxygen, 400-800 ℃) is an experimental technology with five outputs (kg/kg sludge TS): char 0.53, tar 0.21, water < 0.05, fly ash set to zero and syngas 0.21. The values are somewhat different for digested sludge. Energy consumption for the pyrolysis of sewage sludge cannot be estimated from the literature. The current literature provides useful data on the main flows of thermal technologies, although large variations are in evidence. However, data are limited on energy consumption and recovery in general, and they are scarce on direct emissions to the air from incineration.

How Does a "Dry Tap" Impact the Accuracy of Preoperative Aspiration Results in Predicting Chronic Periprosthetic Joint Infection?

BACKGROUND

Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) is challenging to diagnose. We aimed to evaluate the impact of dry taps requiring saline lavage during preoperative intra-articular hip aspiration on the accuracy of diagnosing PJI before revision surgery.

METHODS

A retrospective review was conducted for THA patients with suspected PJI who received an image-guided hip aspiration from May 2016 to February 2020. Musculoskeletal Infection Society (MSIS) diagnostic criteria for PJI were compared between patients who had dry tap (DT) vs successful tap (ST). Sensitivity and specificity of synovial markers were compared between the DT and ST groups. Concordance between preoperative and intraoperative cultures was determined for the 2 groups.

RESULTS

In total, 335 THA patients met inclusion criteria. A greater proportion of patients in the ST group met MSIS criteria preoperatively (30.2% vs 8.3%, P < .001). Patients in the ST group had higher rates of revision for PJI (28.4% vs 17.5%, P = .026) and for any indication (48.4% vs 36.7%, P = .039). MSIS synovial white blood cell count thresholds were more sensitive in the ST group (90.0% vs 66.7%). There was no difference in culture concordance (67.9% vs 65.9%, P = .709), though the DT group had a higher rate of negative preoperative cultures followed by positive intraoperative cultures (85.7% vs 41.1%, P = .047).

CONCLUSION

Our results indicate that approximately one third of patients have dry hip aspiration, and in these patients cultures are less predictive of intraoperative findings. This suggests that surgeons considering potential PJI after THA should apply extra scrutiny when interpreting negative results in patients who require saline lavage for hip joint aspiration.

Environmental assessment of amending the Amager Bakke incineration plant in Copenhagen with carbon capture and storage

Amending municipal solid waste incineration with carbon capture and storage (CCS) is a new approach that can reduce the climate change impacts of waste incineration. This study provides a detailed analysis of the consequences of amending the new Amager Bakke incinerator in Copenhagen (capacity: 600,000 tonnes waste per year) with CCS as a post-combustion technology. Emphasis is on the changes in the energy flows and outputs as well as the environmental performance of the plant; the latter is assessed by life cycle assessment. Amending Amager Bakke with CCS of the chosen configuration reduces the electricity output by 50% due to steam use by the capture unit, but introducing post-capture flue gas condensation increases the heat output utilized in the Copenhagen district heating system by 20%. Thus, the overall net energy efficiency is not affected. The CCS amendment reduces the fossil CO₂ emissions to 40 kg CO₂ per tonne of incinerated waste and stores 530 kg biogenic CO₂ per tonne of incinerated waste. Potential developments in the composition of the residual waste incinerated or in the energy systems that Amager Bakke interacts with, do not question the benefits of the CCS amendment. In terms of climate change impacts, considering different waste composition and energy system scenarios, introducing CCS reduces in average the impact of Amager Bakke by 850 kg CO₂-equivalents per tonne of incinerated waste. CCS increases the environmental impacts in other categories, but not in the same order of magnitude as the savings introduced within climate change.

Quantifying global warming potential of alternative biorefinery systems for producing fuels from Chinese food waste

Biorefining of Chinese food waste (FW) into transport fuels was assessed in terms of amount of fuel produced and over all Global Warming Potential (GWP) for six different scenarios including biogas, biomethane, bioethanol and biodiesel in different combinations. The life-cycle perspective used included GWP aspects of material and energy use, emissions during biorefining and management of residues, as well as substitution of fossil fuels according to the energy content of biofuels. All of the six FW biorefineries revealed savings in GWP ranging from -19 to -138 kg CO₂ eqv. per ton of wet FW. Compared to the reference scenario with only anaerobic digestion (S0), introducing biogas upgrading to biomethane (S1) improved the GWP by 37%; while producing bioethanol prior to anaerobic digestion (S2) decreased the savings in GWP. Introducing biodiesel prior to anaerobic digestion (S3) revealed around 60% improvement in GWP, while combining biodiesel and biomethane gave the largest improvement in GWP, 84% compared to the reference scenario, and the most fuels (around 2400 MJ in terms of 30 kg biodiesel and 35 kg biomethane per ton of wet FW). A sensitivity analysis revealed that the electricity production based on the biogas was an important parameter and appears in all refineries, while the results was less sensitive to the production of biodiesel and biomethane. The residue management contributed also to the GWP, but did not vary much among the biorefinery scenarios.

Environmental assessment of carbon capture and storage (CCS) as a post-treatment technology in waste incineration

The effects of amending municipal solid waste incineration (MSWI) with carbon capture and storage (CCS) via MEA (Monoethanolamine) technology differ according to the air pollution control technologies and energy recovery systems. Electricity output reduces by one-third for power-only plants and halves for combined heat-and-power plants, while variations in heat recovery depend on the presence of flue gas condensation. MSWI with CCS can capture roughly 800 kg of compressed CO₂ per tonne of waste treated. Life cycle assessment (LCA) modelling of MSWI, with and without CCS, illustrates that despite energy penalties, CCS lowers its climate change impact. The difference in climate change impacts as a result of CCS amendment depends on the energy system in which MSWI operates. In a near-future energy system, MSWI with CCS reduces climate change impacts by 700 kg CO₂-eq/tonne wet waste compared to MSWI without CCS. The climate change saving of CCS became increasingly larger as the energy system became "greener"; the climate change saving ultimately approached the capture efficiency (85% of CO₂ in the flue gas) multiplied by the carbon content of the waste converted to CO₂. Sensitivity analysis showed that capture efficiency was the main factor affecting the overall results, with increasing importance in non-fossil fuel-based energy systems. Likely changes in residual waste composition, as source segregation and collection systems improve, had only minor effects on the environmental benefits of CCS. The effects of CCS amendments on 13 other impact categories were marginal compared to the effects of different MSWI configurations.

Climate change impacts of introducing carbon capture and utilisation (CCU) in waste incineration

Amending municipal solid waste incineration (MSWI) with carbon capture and utilisation (CCU) can simultaneously lower the climate change impacts of incineration and supply carbon for a range of uses. However, life cycle assessment (LCA) shows that technology choices and the benefits of CCU applied to MSWI depend on the energy system in which the MSWI operates throughout its lifetime, and on the markets for the CCU products. Carbon capture reduces up to 50% of the energy recovery of MSWI. We assessed different energy system scenarios, ranging from fossil- to non-fossil based. Direct utilisation of the captured CO₂ is beneficial only on a local basis when substituting fossil-based CO₂ (-700 kg CO₂-eq/tonne waste), with benefits similar to carbon capture and storage. Hydrogenation of CO₂ with the purpose of producing feedstock chemicals or fuels such as methane, methanol, dimethyl ether (DME) and formic acid provides much higher benefits (-2000 kg CO₂-eq/tonne waste), but only in non-fossil-based energy systems, due to the dramatically high consumption of electricity (more than 6000 kWh/tonne waste). Use as feedstock chemicals provides more benefits than use as fuels, and CCU solutions focusing on methanol and DME are the most promising technologies. Although built on scarce and early-development data, the analysis highlights current crucial issues, at both the technological and system levels, for the future introduction of CCU in MSWI.

Application of LCA modelling in integrated waste management

Life cycle assessment (LCA) has been used in waste management for the last two decades and hundreds of journal papers have been published. The use of LCA in waste management has provided a much-improved holistic view of waste management including waste flows and potential environmental impacts. Although much knowledge has been obtained from LCA studies, there is still a need to use LCA models in integrated waste management. This paper describes six areas where LCA is expected to play a role in waste management in the future: 1) understanding an existing waste management system; 2) improving existing waste management systems; 3) comparing alternative technologies/ technology performance; 4) technology development/prospective technologies; 5) policy development/strategic development; and 6) reporting. Illustrative examples are provided for each application area.

Life cycle assessment of garden waste management options including long-term emissions after land application

A life cycle assessment (LCA) was performed on five garden waste treatment practices: the production of mature compost including the woody fraction (MCIW), the production of mature compost without the woody fraction (MCWW), the production of immature compost without the woody fraction (ICWW), fresh garden waste including the woody fraction (GWIW) and fresh garden waste without the woody fraction (GWWW). The assessment included carbon sequestration after land application of the garden waste and composts, and associated emissions. The removed woody fraction was incinerated and energy recovery included as heat and electricity. The functional unit of the assessment was treatment of 1000 kg of garden waste generated in Denmark. Overall, the results showed that composting of garden waste resulted in comparable or higher environmental impact potentials (depletion of abiotic resources, marine eutrophication, and terrestrial eutrophication and acidification) than no treatment before land application. The toxicity potentials showed the highest normalised impact potentials for all the scenarios, but were unaffected by the different garden waste treatments. The choice of energy source for substituted heat and electricity production affected the performance of the different treatment scenarios with respect to climate change. The scenarios with removal of the woody fraction performed better than the scenarios without removal of the woody fraction when fossil energy sources were substituted, but performed worse when renewable energy sources were substituted. Furthermore, the study showed the importance of including long-term emission factors after land application of fresh and composted garden waste products since the greatest proportion of carbon and nitrogen emissions occurred after land application in three out of the five scenarios for carbon and in all scenarios for nitrogen.

Waste management in the Irkutsk region, Siberia, Russia: An environmental assessment of alternative development scenarios

The current waste management system, handling around 500,000 t of household, commercial, and institutional waste annually in the Irkutsk region, Siberia, is based on landfilling in an old landfill with no controls of leachate and gas. Life-cycle assessment modelling of the current system shows that it is a major load on the environment, while the simulation of seven alternative systems results in large savings in many impact categories. With respect to climate change, it is estimated that a saving of about 1200 kg CO₂ equivalents is possible per year, per inhabitant, which is a significant reduction in greenhouse gas emissions. The best alternatives involve efficient energy recovery from waste and recycling by source separation for commercial and institutional waste, the major waste type in the Irkutsk region. Recycling of household waste seems less attractive, and it is therefore recommended only to consider this option after experience has been gained with the commercial and institutional waste. Sensitivity analysis shows that recovery of energy - in particular electricity, heat, and steam - from waste is crucial to the environmental performance of the waste management system. This relates to the efficiencies of energy recovery as well as what the recovered energy substitutes, that is, the 'dirtier' the off-set energy, the higher the environmental savings for the waste management system. Since recovered energy may be utilised by only a few energy grids or industrial users, it is recommended to perform additional local assessments of the integration of the waste energy into existing systems and facilities.

Environmental performance of household waste management in Europe - An example of 7 countries

An attributional life cycle assessment (LCA) of the management of 1ton of household waste was conducted in accordance with ISO 14044:2006 and the ILCD Handbook for seven European countries, namely Germany, Denmark, France, UK, Italy, Poland and Greece, representing different household waste compositions, waste management practices, technologies, and energy systems. National data were collected from a range of sources regarding household waste composition, household sorting efficiency, collection, waste treatments, recycling, electricity and heat composition, and technological efficiencies. The objective was to quantify the environmental performance in the different countries, in order to analyze the sources of the main environmental impacts and national differences which affect the results. In most of the seven countries, household waste management provides environmental benefits when considering the benefits of recycling of materials and recovering and utilization of energy. Environmental benefits come from paper recycling and, to a lesser extent, the recycling of metals and glass. Waste-to-energy plants can lead to an environmental load (as in France) or a saving (Germany and Denmark), depending mainly on the composition of the energy being substituted. Sensitivity analysis and a data quality assessment identified a range of critical parameters, suggesting from where better data should be obtained. The study concluded that household waste management is environmentally the best in European countries with a minimum reliance on landfilling, also induced by the implementation of the Waste Hierarchy, though environmental performance does not correlate clearly with the rate of material recycling. From an environmental point of view, this calls for a change in the waste management paradigm, with less focus on where the waste is routed and more of a focus on the quality and utilization of recovered materials and energy.

Life cycle assessment of capital goods in waste management systems

The environmental importance of capital goods (trucks, buildings, equipment, etc.) was quantified by LCA modelling 1 tonne of waste treated in five different waste management scenarios. The scenarios involved a 240L collection bin, a 16m(3) collection truck, a composting plant, an anaerobic digestion plant, an incinerator and a landfill site. The contribution of capital goods to the overall environmental aspects of managing the waste was significant but varied greatly depending on the technology and the impact category: Global Warming: 1-17%, Stratospheric Ozone Depletion: 2-90%, Ionising Radiation, Human Health: 2-91%, Photochemical Ozone Formation: 2-56%, Freshwater Eutrophication: 0.05-99%, Marine Eutrophication: 0.03-8%, Terrestrial Acidification: 2-13%, Terrestrial Eutrophication: 1-8%, Particulate Matter: 11-26%, Human Toxicity, Cancer Effect: 10-92%, Human Toxicity, non-Cancer Effect: 1-71%, Freshwater Ecotoxicity: 3-58%. Depletion of Abiotic Resources - Fossil: 1-31% and Depletion of Abiotic Resources - Elements (Reserve base): 74-99%. The single most important contribution by capital goods was made by the high use of steel. Environmental impacts from capital goods are more significant for treatment facilities than for the collection and transportation of waste and for the landfilling of waste. It is concluded that the environmental impacts of capital goods should always be included in the LCA modelling of waste management, unless the only impact category considered is Global Warming.

Soil retention of hexavalent chromium released from construction and demolition waste in a road-base-application scenario

We investigated the retention of Cr(VI) in three subsoils with low organic matter content in laboratory experiments at concentration levels relevant to represent leachates from construction and demolition waste (C&DW) reused as unbound material in road construction. The retention mechanism appeared to be reduction and subsequent precipitation as Cr(III) on the soil. The reduction process was slow and in several experiments it was still proceeding at the end of the six-month experimental period. The overall retention reaction fit well with a second-order reaction governed by actual Cr(VI) concentration and reduction capacity of the soil. The experimentally determined reduction capacities and second-order kinetic parameters were used to model, for a 100-year period, the one-dimensional migration of Cr(VI) in the subsoil under a layer of C&DW. The resulting Cr(VI) concentration would be negligible below 7-70 cm depth. However, in rigid climates and with high water infiltration through the road pavement, the reduction reaction could be so slow that Cr(VI) might migrate as deep as 200 cm under the road. The reaction parameters and the model can form the basis for systematically assessing under which scenarios Cr(VI) from C&DW could lead to an environmental issue for ground- and receiving surface waters.

A comprehensive substance flow analysis of a municipal wastewater and sludge treatment plant

The fate of total organic carbon, 32 elements (Al, Ag, As, Ba, Be, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, N, Na, Ni, P, Pb, S, Sb, Se, Sn, Sr, Ti, V, and Zn) and 4 groups of organic pollutants (linear alkylbenzene sulfonates, bis(2-ethylhexyl)phthalate, polychlorinated biphenyl and polycyclic aromatic hydrocarbons) in a conventional wastewater treatment plant were assessed. Mass balances showed reasonable closures for most of the elements. However, gaseous emissions were accompanied by large uncertainties and show the limitation of mass balance based substance flow analysis. Based on the assessment, it is evident that both inorganic and organic elements accumulated in the sewage sludge, with the exception of elements that are highly soluble or degradable by wastewater and sludge treatment processes. The majority of metals and metalloids were further accumulated in the incineration ash, while the organic pollutants were effectively destroyed by both biological and thermal processes. Side streams from the sludge treatment process (dewatering and incineration) back to the wastewater treatment represented less than 1% of the total volume entering the wastewater treatment processes, but represented significant substance flows. In contrast, the contribution by spent water from the flue gas treatment process was almost negligible. Screening of human and eco-toxicity by applying the consensus-based environmental impact assessment method USEtox addressing 15 inorganic constituents showed that removal of inorganic constituents by the wastewater treatment plant reduced the toxic impact potential by 87-92%.

Life cycle assessment of construction and demolition waste management

Life cycle assessment (LCA) modelling of construction and demolition waste (C&DW) management was carried out. The functional unit was management of 1 Mg mineral, source separated C&DW, which is either utilised in road construction as a substitute for natural aggregates, or landfilled. The assessed environmental impacts included both non-toxic and toxic impact categories. The scenarios comprised all stages of the end-of-life management of C&DW, until final disposal of all residues. Leaching of inorganic contaminants was included, as was the production of natural aggregates, which was avoided because of the use of C&DW. Typical uncertainties related to contaminant leaching were addressed. For most impact categories, utilisation of C&DW in road construction was preferable to landfilling; however, for most categories, utilisation resulted in net environmental burdens. Transportation represented the most important contribution for most nontoxic impacts, accounting for 60-95 per cent of these impacts. Capital goods contributed with negligible impacts. Leaching played a critical role for the toxic categories, where landfilling had lower impacts than utilisation because of the lower levels of leachate per ton of C&DW reaching the groundwater over a 100-year perspective. Leaching of oxyanions (As, V and Sb) was critical with respect to leaching. Typical experimental uncertainties in leaching data did not have a pivotal influence on the results; however, accounting for Cr immobilisation in soils as part of the impact assessment was critical for modelling the leaching impacts. Compared with the overall life cycle of building and construction materials, leaching emissions were shown to be potentially significant for toxicity impacts, compared with contributions from production of the same materials, showing that end-of-life impacts and leaching should not be disregarded when assessing environmental impacts from construction products and materials. CO2 uptake in the C&DW corresponding to 15 per cent carbonation could out-balance global warming impacts from transportation; however, carbonation would also likely result in increased toxicity impacts due to higher leaching of oxyanions.

Construction and demolition waste: Comparison of standard up-flow column and down-flow lysimeter leaching tests

Five samples of construction and demolition waste (C&DW) were investigated in order to quantify leaching of inorganic elements under percolation conditions according to two different experimental setups: standardised up-flow saturated columns (<4mm particle size) and unsaturated, intermittent down-flow lysimeters (<40mm particle size). While standardised column tests are meant primarily to provide basic information on characteristic leaching properties and mechanisms and not to reproduce field conditions, the lysimeters were intended to mimic the actual leaching conditions when C&DW is used in unbound geotechnical layers. In practice, results from standardised percolation tests are often interpreted as estimations of actual release from solid materials in percolation scenarios. In general, the two tests yielded fairly similar results in terms of cumulative release at liquid-to-solid ratio (L/S) 10l·kgTS; however, significant differences were observed for P, Pb, Ba, Mg and Zn. Further differences emerged in terms of concentration in the early eluates (L/S<5l·kg(-1)TS) for Al, As, Ba, Cd, Cu, DOC, Mg, Mn, Ni, P, Pb, Sb, Se, Si, Zn. Observed differences between tests are likely to be due to differences in pH related to crushing and exposure of fresh particle surfaces, as well as in equilibrium conditions. In the case of C&DW, the standardised column tests, which are more practical, are considered to acceptably describe cumulative releases at L/S 10l·kg(-1)TS in percolation scenarios. However, when the focus is on estimation of initial concentrations for (for example) risk assessment, data from standardised column tests may not be fully applicable, and data from lysimeters may be used for validation purposes. Se, Cr and, to a lesser extent, SO4 and Sb were leaching from C&DW in critical amounts compared with existing limit values.

Quantifying capital goods for biological treatment of organic waste

Materials and energy used for construction of anaerobic digestion (AD) and windrow composting plants were quantified in detail. The two technologies were quantified in collaboration with consultants and producers of the parts used to construct the plants. The composting plants were quantified based on the different sizes for the three different types of waste (garden and park waste, food waste and sludge from wastewater treatment) in amounts of 10,000 or 50,000 tonnes per year. The AD plant was quantified for a capacity of 80,000 tonnes per year. Concrete and steel for the tanks were the main materials for the AD plant. For the composting plants, gravel and concrete slabs for the pavement were used in large amounts. To frame the quantification, environmental impact assessments (EIAs) showed that the steel used for tanks at the AD plant and the concrete slabs at the composting plants made the highest contribution to Global Warming. The total impact on Global Warming from the capital goods compared to the operation reported in the literature on the AD plant showed an insignificant contribution of 1-2%. For the composting plants, the capital goods accounted for 10-22% of the total impact on Global Warming from composting.

Composition and leaching of construction and demolition waste: inorganic elements and organic compounds

Thirty-three samples of construction and demolition waste collected at 11 recycling facilities in Denmark were characterised in terms of total content and leaching of inorganic elements and presence of the persistent organic pollutants PCBs and PAHs. Samples included (i) "clean" (i.e. unmixed) concrete waste, (ii) mixed masonry and concrete, (iii) asphalt and (iv) freshly cast concrete cores; both old and newly generated construction and demolition waste was included. PCBs and PAHs were detected in all samples, generally in non-critical concentrations. Overall, PAHs were comparable to background levels in urban environments. "Old" and "new" concrete samples indicated different PCB congener profiles and the presence of PCB even in new concrete suggested that background levels in raw materials may be an issue. Significant variability in total content of trace elements, even more pronounced for leaching, was observed indicating that the number of analysed samples may be critical in relation to decisions regarding management and utilisation of the materials. Higher leaching of chromium, sulphate and chloride were observed for masonry-containing and partly carbonated samples, indicating that source segregation and management practices may be important. Generally, leaching was in compliance with available leaching limits, except for selenium, and in some cases chromium, sulphate and antimony.

Influence of data collection schemes on the Life Cycle Assessment of a municipal wastewater treatment plant

A Life Cycle Assessment (LCA) of a municipal wastewater treatment plant (WWTP) was conducted to illustrate the effect of an emission inventory data collection scheme on the outcomes of an environmental impact assessment. Due to their burden in respect to data collection, LCAs often rely heavily on existing emission and operational data, which are gathered under either compulsory monitoring or reporting requirements under law. In this study, an LCA was conducted using three input data sources: Information compiled under compulsory disclosure requirements (the European Pollutant Release and Transfer Registry), compliance with national discharge limits, and a state-of-the-art emission data collection scheme conducted at the same WWTP. Parameter uncertainty for each collection scheme was assessed through Monte Carlo simulation. The comparison of the results confirmed that LCA results depend heavily on input data coverage. Due to the threshold on reporting value, the E-PRTR did not capture the impact for particulate matter emission, terrestrial acidification, or terrestrial eutrophication. While the current practice can capture more than 90% of non-carcinogenic human toxicity and marine eutrophication, an LCA based on the data collection scheme underestimates impact potential due to limitations of substance coverage. Besides differences between data collection schemes, the results showed that 3-13,500% of the impacts came from background systems, such as from the provisioning of fuel, electricity, and chemicals, which do not need to be disclosed currently under E-PRTR. The incidental release of pollutants was also assessed by employing a scenario-based approach, the results of which demonstrated that these non-routine emissions could increase overall WWTP greenhouse gas emissions by between 113 and 210%. Overall, current data collection schemes have the potential to provide standardized data collection and form the basis for a sound environmental impact assessment, but several improvements are recommended, including the additional collection of energy and chemical usage data, the elimination of a reporting threshold, the expansion of substance coverage, and the inclusion of non-point fugitive gas emissions.

Waste management in the Irkutsk Region, Siberia, Russia: environmental assessment of current practice focusing on landfilling

The municipal waste management system of the region of Irkutsk is described and a life cycle assessment (LCA) performed to assess the environmental performance of the system. Annually about 500 000 tons of waste are managed. The waste originates from three sources: household waste (27%), commercial waste (23%) and office & institutional waste (44%). Other waste of unknown composition constitutes 6%. Only 3% of the waste is recycled; 97% of the municipal waste is disposed of at the old Alexandrovsky landfill. The environmental impact from the current system is dominated by the landfill, which has no gas or leachate collection system. The global warming contribution is due to the emission of methane of the order of 420 000 tons CO2-equivalents per year. Collection and transport of the waste are insignificant compared with impacts from the landfill. As the old landfill runs out of capacity in a few years, the LCA modelling showed that introduction of a new and modern landfill with gas and leachate collection could improve the performance of the waste management system significantly. Collection of landfill gas and utilization for 30 years for electricity production (gas turbine) would reduce the global warming completely and result in a net saving of 100 000 CO2-equivalents per year due to storage of biogenic carbon in the landfill beyond 100 years. Considering other first-order degradation rates for the landfilled organic matter did not overtly affect the results, while assumptions about the top cover oxidation of methane significantly affected the results. This shows the importance of controlling the gas escape from the landfill.

Review of LCA studies of solid waste management systems--part II: methodological guidance for a better practice

Life cycle assessment (LCA) is increasingly used in waste management to identify strategies that prevent or minimise negative impacts on ecosystems, human health or natural resources. However, the quality of the provided support to decision- and policy-makers is strongly dependent on a proper conduct of the LCA. How has LCA been applied until now? Are there any inconsistencies in the past practice? To answer these questions, we draw on a critical review of 222 published LCA studies of solid waste management systems. We analyse the past practice against the ISO standard requirements and the ILCD Handbook guidelines for each major step within the goal definition, scope definition, inventory analysis, impact assessment, and interpretation phases of the methodology. Results show that malpractices exist in several aspects of the LCA with large differences across studies. Examples are a frequent neglect of the goal definition, a frequent lack of transparency and precision in the definition of the scope of the study, e.g. an unclear delimitation of the system boundaries, a truncated impact coverage, difficulties in capturing influential local specificities such as representative waste compositions into the inventory, and a frequent lack of essential sensitivity and uncertainty analyses. Many of these aspects are important for the reliability of the results. For each of them, we therefore provide detailed recommendations to practitioners of waste management LCAs.

Review of LCA studies of solid waste management systems--part I: lessons learned and perspectives

The continuously increasing solid waste generation worldwide calls for management strategies that integrate concerns for environmental sustainability. By quantifying environmental impacts of systems, life cycle assessment (LCA) is a tool, which can contribute to answer that call. But how, where and to which extent has it been applied to solid waste management systems (SWMSs) until now, and which lessons can be learnt from the findings of these LCA applications? To address these questions, we performed a critical review of 222 published LCA studies of SWMS. We first analysed the geographic distribution and found that the published studies have primarily been concentrated in Europe with little application in developing countries. In terms of technological coverage, they have largely overlooked application of LCA to waste prevention activities and to relevant waste types apart from household waste, e.g. construction and demolition waste. Waste management practitioners are thus encouraged to abridge these gaps in future applications of LCA. In addition to this contextual analysis, we also evaluated the findings of selected studies of good quality and found that there is little agreement in the conclusions among them. The strong dependence of each SWMS on local conditions, such as waste composition or energy system, prevents a meaningful generalisation of the LCA results as we find it in the waste hierarchy. We therefore recommend stakeholders in solid waste management to regard LCA as a tool, which, by its ability of capturing the local specific conditions in the modelling of environmental impacts and benefits of a SWMS, allows identifying critical problems and proposing improvement options adapted to the local specificities.

Review of LCA studies of solid waste management systems--part II: methodological guidance for a better practice

Life cycle assessment (LCA) is increasingly used in waste management to identify strategies that prevent or minimise negative impacts on ecosystems, human health or natural resources. However, the quality of the provided support to decision- and policy-makers is strongly dependent on a proper conduct of the LCA. How has LCA been applied until now? Are there any inconsistencies in the past practice? To answer these questions, we draw on a critical review of 222 published LCA studies of solid waste management systems. We analyse the past practice against the ISO standard requirements and the ILCD Handbook guidelines for each major step within the goal definition, scope definition, inventory analysis, impact assessment, and interpretation phases of the methodology. Results show that malpractices exist in several aspects of the LCA with large differences across studies. Examples are a frequent neglect of the goal definition, a frequent lack of transparency and precision in the definition of the scope of the study, e.g. an unclear delimitation of the system boundaries, a truncated impact coverage, difficulties in capturing influential local specificities such as representative waste compositions into the inventory, and a frequent lack of essential sensitivity and uncertainty analyses. Many of these aspects are important for the reliability of the results. For each of them, we therefore provide detailed recommendations to practitioners of waste management LCAs.

Life cycle assessment of sewage sludge management: a review

In this article, 35 published studies on life cycle assessment (LCA) of sewage sludge were reviewed for their methodological and technological assumptions. Overall, LCA has been providing a flexible framework to quantify environmental impacts of wastewater and sewage sludge treatment and disposal processes for multiple scales, ranging from process selection to policy evaluation. The results of LCA are, in principle, unique to the goal and scope of each study, reflecting its local conditions and comparison between different LCAs is not intended. Furthermore, the assessments are limited by the methodological development of the life cycle impact assessment (LCIA) and the advancement of research in quantifying environmental emissions associated with wastewater and sewage sludge treatment processes. Thus, large discrepancies were found in the selection of the environmental emissions to be included and how they were estimated in the analysis. In order to reduce these choice uncertainties, consolidation of the modelling approach in the following area are recommended: quantification of fugitive gas emissions and modelling of disposal practices. Besides harmonization of the key technical assumptions, clear documentation of the modelling approach and the uncertainties associating with each assumption is encouraged so as to improve the integrity and robustness of assessment.

WEEE and portable batteries in residual household waste: quantification and characterisation of misplaced waste

A total of 26.1Mg of residual waste from 3129 households in 12 Danish municipalities was analysed and revealed that 89.6kg of Waste Electrical and Electronic Equipment (WEEE), 11kg of batteries, 2.2kg of toners and 16kg of cables had been wrongfully discarded. This corresponds to a Danish household discarding 29g of WEEE (7 items per year), 4g of batteries (9 batteries per year), 1g of toners and 7g of unidentifiable cables on average per week, constituting 0.34% (w/w), 0.04% (w/w), 0.01% (w/w) and 0.09% (w/w), respectively, of residual waste. The study also found that misplaced WEEE and batteries in the residual waste constituted 16% and 39%, respectively, of what is being collected properly through the dedicated special waste collection schemes. This shows that a large amount of batteries are being discarded with the residual waste, whereas WEEE seems to be collected relatively successfully through the dedicated special waste collection schemes. Characterisation of the misplaced batteries showed that 20% (w/w) of the discarded batteries were discarded as part of WEEE (built-in). Primarily alkaline batteries, carbon zinc batteries and alkaline button cell batteries were found to be discarded with the residual household waste. Characterisation of WEEE showed that primarily small WEEE (WEEE directive categories 2, 5a, 6, 7 and 9) and light sources (WEEE directive category 5b) were misplaced. Electric tooth brushes, watches, clocks, headphones, flashlights, bicycle lights, and cables were items most frequently found. It is recommended that these findings are taken into account when designing new or improving existing special waste collection schemes. Improving the collection of WEEE is also recommended as one way to also improve the collection of batteries due to the large fraction of batteries found as built-in. The findings in this study were comparable to other western European studies, suggesting that the recommendations made in this study could apply to other western European countries as well.

Quantifying capital goods for waste incineration

Materials and energy used for the construction of modern waste incineration plants were quantified. The data was collected from five incineration plants (72,000-240,000 tonnes per year) built in Scandinavia (Norway, Finland and Denmark) between 2006 and 2012. Concrete for the buildings was the main material used amounting to 19,000-26,000 tonnes per plant. The quantification further included six main materials, electronic systems, cables and all transportation. The energy used for the actual on-site construction of the incinerators was in the range 4000-5000 MW h. In terms of the environmental burden of producing the materials used in the construction, steel for the building and the machinery contributed the most. The material and energy used for the construction corresponded to the emission of 7-14 kg CO2 per tonne of waste combusted throughout the lifetime of the incineration plant. The assessment showed that, compared to data reported in the literature on direct emissions from the operation of incinerators, the environmental impacts caused by the construction of buildings and machinery (capital goods) could amount to 2-3% with respect to kg CO2 per tonne of waste combusted.

Quantifying capital goods for waste landfilling

Materials and energy used for construction of a hill-type landfill of 4 million m(3) were quantified in detail. The landfill is engineered with a liner and leachate collections system, as well as a gas collection and control system. Gravel and clay were the most common materials used, amounting to approximately 260 kg per tonne of waste landfilled. The environmental burdens from the extraction and manufacturing of the materials used in the landfill, as well as from the construction of the landfill, were modelled as potential environmental impacts. For example, the potential impact on global warming was 2.5 kg carbon dioxide (CO2) equivalents or 0.32 milli person equivalents per tonne of waste. The potential impacts from the use of materials and construction of the landfill are low-to-insignificant compared with data reported in the literature on impact potentials of landfills in operation. The construction of the landfill is only a significant contributor to the impact of resource depletion owing to the high use of gravel and steel.