A review of emerging membrane-based microalgal-bacterial processes for wastewater treatment: Process configurations, biological and membrane performance, and perspectives

Microalgal-bacterial (MB) consortia create an excellent eco-system for simultaneous COD/BOD and nutrients (N and P) removals in a single step with significant reduction in or complete elimination of aeration and carbonation in the biological wastewater treatment processes. The integration of membrane separation technology with the MB processes has created a new paradigm for research and development. This paper focuses on a comprehensive and critical literature review of recent advances in these emerging processes. Novel membrane process configurations and process conditions affecting the biological performance of these novel systems have been systematically reviewed and discussed. Membrane fouling issues and control of MB biofilm formation and thickness associated with these emerging suspended growth or immobilized biofilm processes are addressed and discussed. The research gaps, challenges, outlooks of these emerging processes are identified and discussed in-depth. The findings from the literature suggest that the membrane-based MB processes are advanced biotechnologies with a significant reduction in energy consumption and process simplification and high process efficiency that are not achievable with current technologies in wastewater treatment. There are endless opportunities for research and development of these novel and emerging membrane-based MB processes.

A Light Touch: Solar Photocatalysis Detoxifies Oil Sands Process-Affected Waters Prior to Significant Treatment of Naphthenic Acids

Environmental reclamation of Canada's oil sands tailings ponds is among the single largest water treatment challenges globally. The toxicity of oil sands process-affected water (OSPW) has been associated with its dissolved organics, a complex mixture of naphthenic acid fraction components (NAFCs). Here, we evaluated solar treatment with buoyant photocatalysts (BPCs) as a passive advanced oxidation process (P-AOP) for OSPW remediation. Photocatalysis fully degraded naphthenic acids (NAs) and acid extractable organics (AEO) in 3 different OSPW samples. However, classical NAs and AEO, traditionally considered among the principal toxicants in OSPW, were not correlated with OSPW toxicity herein. Instead, nontarget petroleomic analysis revealed that low-polarity organosulfur compounds, composing <10% of the total AEO, apparently accounted for the majority of waters' toxicity to fish, as described by a model of tissue partitioning. These findings have implications for OSPW release, for which a less extensive but more selective treatment may be required than previously expected.

Roles of pH and phosphate in rare earth element biosorption with living acidophilic microalgae

The increasing demand for rare earth elements (REEs) has spurred interest in the development of recovery methods from aqueous waste streams. Acidophilic microalgae have gained attention for REE biosorption as they can withstand high concentrations of transition metals and do not require added organic carbon to grow, potentially allowing simultaneous sorption and self-replication of the sorbent. Here, we assessed the potential of Galdieria sulphuraria for REE biosorption under acidic, nutrient-replete conditions from solutions containing ≤ 15 ppm REEs. Sorption at pH 1.5-2.5 (the growth optimum of G. sulphuraria) was poor but improved up to 24-fold at pH 5.0 in phosphate-free conditions. Metabolic activity had a negative impact on REE sorption, additionally challenging the feasibility of REE biosorption under ideal growth conditions for acidophiles. We further examined the possibility of REE biosorption in the presence of phosphate for biomass growth at elevated pH (pH ≥ 2.5) by assessing aqueous La concentrations in various culture media. Three days after adding La into the media, dissolved La concentrations were up to three orders of magnitude higher than solubility predictions due to supersaturation, though LaPO4 precipitation occurred under all conditions when seed was added. We concluded that biosorption should occur separately from biomass growth to avoid REE phosphate precipitation. Furthermore, we demonstrated the importance of proper control experiments in biosorption studies to assess potential interactions between REEs and matrix ions such as phosphates. KEY POINTS: • REE biosorption with G. sulphuraria increases significantly when raising pH to 5 • Phosphate for biosorbent growth has to be supplied separately from biosorption • Biosorption studies have to assess potential matrix effects on REE behavior.

Determining the performance of lignin-based flocculants in improving biosludge dewaterability

In the wastewater treatment plant of pulp and paper mills, biosludge dewatering is needed to reduce the sludge handling and disposal costs. It is usually facilitated by means of the addition of synthetic polymers. There is increasing interest in replacing synthetic polymers with biopolymers derived from low value by-products or industrial residuals to improve the environmental footprint of dewatering. In this study, lignin-based flocculants (LBF) were tested for their ability to improve the biosludge dewaterability based on Capillary Suction Time (CST) and dry cake solids achieved with a Crown Press. The results demonstrate that LBFs alone can significantly enhance dewatering with a decrease in CSTs from 72.7 ± 5.1 s (unconditioned biosludge) to 23.3 ± 0.4 s and an increase in dry cake solids after pressing from 7.1 ± 0.5% to 13.9 ± 1.3% with a relatively high dosage of 7.5% w/w. However, with dual conditioning a LBF and 0.1% w/w anionic polyacrylamide (APAM), the required dosage of LBF was reduced to 3% w/w to achieve a dry cake solids content of 13.8 ± 0.4%, the same as that achieved with Zetag8165, a commercial synthetic polymer. LBF addition lowered the particle surface charge, allowing the particles to agglomerate and enhancing for the biosludge dewaterability. The application of LBFs for sludge dewatering offers novel considerable promise for providing more sustainable approaches by optimizing the use of lignin from different extraction processes, applying various types of lignin modifications in combination with anionic polymers, and exploring different methods of disposal or utilization of the dewatered sludge.

Engineering Photosynthetic Bioprocesses for Sustainable Chemical Production: A Review

Microbial production of chemicals using renewable feedstocks such as glucose has emerged as a green alternative to conventional chemical production processes that rely primarily on petroleum-based feedstocks. The carbon footprint of such processes can further be reduced by using engineered cells that harness solar energy to consume feedstocks traditionally considered to be wastes as their carbon sources. Photosynthetic bacteria utilize sophisticated photosystems to capture the energy from photons to generate reduction potential with such rapidity and abundance that cells often cannot use it fast enough and much of it is lost as heat and light. Engineering photosynthetic organisms could enable us to take advantage of this energy surplus by redirecting it toward the synthesis of commercially important products such as biofuels, bioplastics, commodity chemicals, and terpenoids. In this work, we review photosynthetic pathways in aerobic and anaerobic bacteria to better understand how these organisms have naturally evolved to harness solar energy. We also discuss more recent attempts at engineering both the photosystems and downstream reactions that transfer reducing power to improve target chemical production. Further, we discuss different methods for the optimization of photosynthetic bioprocess including the immobilization of cells and the optimization of light delivery. We anticipate this review will serve as an important resource for future efforts to engineer and harness photosynthetic bacteria for chemical production.

Enhancing Biosludge Dewaterability with Hemoglobin from Waste Blood as a Bioflocculant

Synthetic polymers are widely used in the treatment of biosludge (waste activated sludge) to enhance its dewaterability. This paper discusses the results of a systematic study using hemoglobin (Hb) from animal blood and methylated hemoglobin (MeHb), a derivative in which a methyl group replaces the hydrogen carboxyl groups, to replace synthetic polymers to improve the dewatering efficiency of biosludge. With regular hemoglobin, no improvement in biosludge dewatering was found. With 10% of methylated hemoglobin per total solids content, however, the dry solids content of biosludge increased from 10.2 (±0.3) wt% to 15.0 (±1.0) wt%. Zeta potential measurements showed a decrease in the negative surface charge of the particles in biosludge from −34.3 (±3.2) mV to −19.0 (±2.1) mV after the treatment with methylated hemoglobin. This, along with an unchanged particle size distribution after conditioning, suggests that charge neutralization is likely the main cause of particle flocculation. With charges neutralized, the extracellular polymeric substances (EPS) around the biosludge flocs become loose, releasing the trapped water, thus increasing dewaterability.

Specific quantification of Scenedesmus obliquus and Chlorella vulgaris in mixed-species algal biofilms

Two TaqMan® qPCR assays were developed to specifically quantify the absolute abundance of Scenedesmus obliquus and Chlorella vulgaris in mixed-species algal biofilms by targeting the psbA gene. Standard curves were developed with amplification efficiencies of 92.4% and 96.6% for S. obliquus and C. vulgaris, respectively, and an R² value of 0.99 for both. Calibration curves for estimating absolute cell abundances resulted in slopes of 0.98 and 1.11 for C. vulgaris and S. obliquus, respectively, and an R² value of 0.95 for both. The assays were applied to cultivated mixed-species biofilms and approximately 10⁷ cells of each algal species were quantified when 10⁷ cells were added into biofilms. The developed qPCR assays were concluded to be specific and accurate for the quantification of S. obliquus and C. vulgaris in mixed-species biofilms. This will contribute to the control and optimization of algal cultivation systems for the production of algal biofuels and bioproducts.

Muscle specific kinase protects dystrophic mdx mouse muscles from eccentric contraction-induced loss of force-producing capacity

KEY POINTS

Adeno-associated viral vector was used to elevate the expression of muscle specific kinase (MuSK) and rapsyn (a cytoplasmic MuSK effector protein) in the tibialis anterior muscle of wild-type and dystrophic (mdx) mice. In mdx mice, enhanced expression of either MuSK or rapsyn ameliorated the acute loss of muscle force associated with strain injury. Increases in sarcolemmal immunolabelling for utrophin and β-dystroglycan suggest a mechanism for the protective effect of MuSK in mdx muscles. MuSK also caused subtle changes to the structure and function of the neuromuscular junction, suggesting novel roles for MuSK in muscle physiology and pathophysiology.

ABSTRACT

Muscle specific kinase (MuSK) has a well-defined role in stabilizing the developing mammalian neuromuscular junction, but MuSK might also be protective in some neuromuscular diseases. In the dystrophin-deficient mdx mouse model of Duchenne muscular dystrophy, limb muscles are especially fragile. We injected the tibialis anterior muscle of 8-week-old mdx and wild-type (C57BL10) mice with adeno-associated viral vectors encoding either MuSK or rapsyn (a cytoplasmic MuSK effector protein) fused to green fluorescent protein (MuSK-GFP and rapsyn-GFP, respectively). Contralateral muscles injected with empty vector served as controls. One month later mice were anaesthetized with isoflurane and isometric force-producing capacity was recorded from the distal tendon. MuSK-GFP caused an unexpected decay in nerve-evoked tetanic force, both in wild-type and mdx muscles, without affecting contraction elicited by direct electrical stimulation of the muscle. Muscle fragility was probed by challenging muscles with a strain injury protocol consisting of a series of four strain-producing eccentric contractions in vivo. When applied to muscles of mdx mice, eccentric contraction produced an acute 27% reduction in directly evoked muscle force output, affirming the susceptibility of mdx muscles to strain injury. mdx muscles overexpressing MuSK-GFP or rapsyn-GFP exhibited significantly milder force deficits after the eccentric contraction challenge (15% and 14%, respectively). The protective effect of MuSK-GFP in muscles of mdx mice was associated with increased immunolabelling for utrophin and β-dystroglycan in the sarcolemma. Elevating the expression of MuSK or rapsyn revealed several distinct synaptic and extrasynaptic effects, suggesting novel roles for MuSK signalling in muscle physiology and pathophysiology.

Evaluating the effect of enzymatic pretreatment on the anaerobic digestibility of pulp and paper biosludge

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A new and rigorous approach for assessing the effect of enzymatic pretreatment on AD is proposed.

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Enzymes can improve anaerobic digestion increasing biogas yields by up to 26%.

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First study to isolate the effect of catalytic activity and organic load from enzymes to evaluate enzymatic pretreatment.

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Enzymes did not appear to be inhibited or denatured in the presence of biosludge.

Anaerobic digestion of biosludge has not yet been implemented in pulp mills due to low biogas yields. Enzymatic pretreatment of biosludge has shown improvements in biogas yields but results are varied. A key limitation of previous studies is that they fail to consider the COD contribution from the enzyme solutions. The aim of this study was to systematically investigate the potential for enzymatic pretreatment on the anaerobic digestibility of pulp mill biosludge. Out of the six enzymes tested, four enhanced the anaerobic digestibility of biosludge. At the end of the BMP, a maximum improvement of 26% in biogas yield was observed with protease from B. licheniformis. There was no correlation between enzymatic activities on standard substrates and/or on biosludge and the effect of enzymes on biogas yields. Enzymes have potential for improving biosludge anaerobic digestibility but more research on optimal conditions and potential synergies with other pretreatment is needed.

The tail of two models: Impact of circularity and biomass non-homogeneity on UV disinfection of wastewater flocs

The effects of floc structural characteristics, i.e. shape and dense biomass distribution, were evaluated on ultraviolet (UV) disinfection resistance, represented by the tailing level of the UV dose response curve (DRC). Ellipsoid-shaped flocs of similar volume and different projected circularities were constructed in-silico and a mathematical model was developed to compare their UV DRC tailing levels (indicative of UV-resistance). It was found that floc shape can significantly influence tailing level, and rounder flocs (i.e. flocs with higher circularity) were more UV-resistant. This result was confirmed experimentally by obtaining UV DRCs of two 75-90 μm floc populations with different percentages (20% vs. 30%) of flocs with circularities higher than 0.5. The population enriched in less circular flocs (i.e. 20% flocs with circularities >0.5) had a lower tailing level (at least by 1-log) compared to the other population. The second model was developed to describe variations in UV disinfection kinetics observed in flocs with transverse vs. radial biomass non-homogeneity, indicative of biofilm-originated vs. suspended flocs. The varied-density hemispheres model and shell-core model were developed to simulate transverse and radial non-homogeneity, respectively. The UV DRCs were mathematically constructed and biofilm-originated flocs showed higher UV resistance compared to suspended flocs. The calculated UV DRCs agreed well with the experimental data collected from activated sludge and trickling filter flocs (no fitting parameters were used). These findings provide useful information in terms of designing/modifying upstream processes for reducing UV disinfection energy demand.

Improved biomass productivity in algal biofilms through synergistic interactions between photon flux density and carbon dioxide concentration

Algal biofilms were grown to investigate the interaction effects of bulk medium CO2 concentration and photon flux density (PFD) on biomass productivities. When increasing the CO2 concentration from 0.04% to 2%, while maintaining a PFD of 100μmol/m(2)/s, biomass productivities increased from ∼0.5 to 2.0g/m(2)/d; however, the productivities plateaued when CO2 concentrations were incrementally increased above 2-12%. Statistical analysis demonstrates that there is a significant interaction between PFD and CO2 concentrations on biomass productivities. By simultaneously increasing PFD and CO2 concentrations, biomass productivities were significantly increased to 4.0 and 4.1g/m(2)/d in the experimental and modeled data, respectively. The second order model predicted increases in biomass productivities as both PFD and CO2 simultaneously increased yielding an optimum at 440μmol/m(2)/s and 7.1%; however, when conditions were extended to the highest end of their respective ranges, the conditions were detrimental to growth and productivities decreased.

Prediction of Rodent Carcinogenesis: An Evaluation of Prechronic Liver Lesions as Forecasters of Liver Tumors in NTP Carcinogenicity Studies

The National Toxicology Program (NTP) developed the chronic 2-year bioassay as a mechanism for predicting the carcinogenic potential of chemicals in humans. The cost and duration of these studies has limited their use to small numbers of selected chemicals. Many different short-term methods aimed at increasing predictive accuracy and the number of chemicals evaluated have been developed in attempts to successfully correlate their results with evidence of carcinogenicity (or lack of carcinogenicity). Using NTP studies, the effectiveness of correlating prechronic liver lesions with liver cancer encompassing multiple studies using mice (83 compounds) and rats (87 compounds) was assessed. These lesions include hepatocellular necrosis, hepatocellular hypertrophy, hepatocellular cytomegaly, bile duct hyperplasia, and hepatocellular degeneration, along with increased liver weight. Our results indicate that pooling 3 of these prechronic data points (hepatocellular necrosis, hepatocellular hypertrophy, and hepatocellular cytomegaly) can be very predictive of carcinogenicity in the 2-year study ( p < 0 .05). The inclusion of increased liver weight as an endpoint in the pool of data points increases the number of rodent liver carcinogens that are successfully predicted ( p < 0 .05), but also results in the prediction of increased numbers of noncarcinogenic chemicals as carcinogens. The use of multiple prechronic study endpoints provides supplementary information that enhances the predictivity of identifying chemicals with carcinogenic potential.

Enhancing pulp and paper mill biosludge dewaterability using enzymes

There have been limited studies on the potential use of enzymes for enhancing the dewaterability of biosludge. The mechanisms for such enhancement have not been investigated despite the environmental advantages of using enzymes over synthetic polymers for biosludge conditioning. In order to find enzymes with this potential, a screening of commercially available enzymes was carried out using capillary suction time to assess biosludge dewaterability. The only enzyme that showed dewatering improvements in the screening tests was a lysozyme which reduced the capillary suction time by 36% and increased the cake solids content from 5.6 to 8.9 DS%. Lysozyme aided in the flocculation of particles reducing the polymer demand from 11% to 6%. Active and inactive lysozyme exhibited a similar ability for enhancing sludge dewatering, indicating that the conditioning mechanism of lysozyme is similar to that of a flocculant.

Enhancing disinfection by advanced oxidation under UV irradiation in polyphosphate-containing wastewater flocs

In this paper, the role of naturally occurring polyphosphate in enhancing the ultraviolet disinfection of wastewater flocs is examined. It was found that polyphosphate, which accumulates naturally within the wastewater flocs in the enhanced biological phosphorus removal process, is capable of producing hydroxyl radicals under UV irradiation and hence causing the photoreactive disinfection of microorganisms embedded within flocs. This phenomenon is likely responsible for the improved UV disinfection of the biological nutrient removal (BNR) effluent compared to that of conventional activated sludge effluent by as much as 1 log. A mathematical model is developed that combines the chemical disinfection by hydroxyl radical formation within flocs, together with the direct inactivation of microorganisms by UV irradiation. The proposed model is able to quantitatively explain the observed improvement in the UV disinfection of the BNR effluents. This study shows that the chemical composition of wastewater flocs could have a significant positive impact on their UV disinfection by inducing the production of oxidative species.

Design of algal film photobioreactors: material surface energy effects on algal film productivity, colonization and lipid content

A parallel plate air lift reactor was used to examine the growth kinetics of mixed culture algal biofilms grown on various materials (acrylic, glass, polycarbonate, polystyrene and cellulose acetate). The growth kinetics of the algal biofilms were non-linear overall and their overall productivities ranged from 1.10-2.08g/m(2)day, with those grown on cellulose acetate having the highest productivity. Overall algal biofilm productivity was largely explained by differences in the colonization time which in turn was strongly correlated to the polar surface energy of the material, but weakly correlated to water-material contact angle. When colonization time was taken into account, the productivity for all materials except acrylic was not significantly different at approximately 2g/m(2)/day. Lipid content of the algal biofilms ranged from 6% to 8% (w/w) and was not correlated to water-material contact angle or polar surface energy. The results have potential application for selecting appropriate materials for algal film photobioreactors.

Algae biofilm growth and the potential to stimulate lipid accumulation through nutrient starvation

An algae biofilm growth system was developed to study the growth kinetics and neutral lipid productivities of Scenedesmus obliquus and Nitzschia palea, and to determine if algal biofilms can be starved of key nutrients to increase their neutral lipid concentrations. Linear growth curves were determined for each species until nutrient starvation commenced, at which point growth ceased and/or biofilms sloughed from their substratum. Nutrient starvation did not increase neutral lipid concentrations in any of the biofilms; however, it approximately doubled their lipid concentrations when grown in suspension. Biomass productivities of 2.8 and 2.1g/m(2)/d and lipid productivities of 0.45 and 0.18 g/m(2)/d were determined for N. palea and S. obliquus, respectively. The results suggest that nutrient starvation of biofilms is not a desirable method of lipid production for algae biofilm biofuel production systems, but that lipid production rates compare favorably with conventional terrestrial biofuel sources.

Adults with intellectual disabilities and challenging behaviour: the costs and outcomes of in- and out-of-area placements

BACKGROUND

People with severe challenging behaviour are vulnerable to exclusion from local services and removal to out-of-area placements if locally available supported accommodation is insufficient to meet their needs. There are concerns about the high costs and potentially poorer outcomes of out-of-area placements but relatively little is known about how costs and outcomes compare with provision for a similar population placed locally.

METHODS

Costs, quality of care and a wide range of quality of life outcomes for 38 people with intellectual disabilities and challenging behaviour living in-area and 38 similar people living out-of-area were compared. The two groups were matched as far as possible on risk factors for out-of-area placement. The out-of-area group represented two-thirds of the total number of people who originated from the territory served by the largest specialist health service in Wales and were placed in residential settings at least 10 miles beyond its boundaries.

RESULTS

There was a mixed pattern of quality of care and quality of outcome advantages between the two types of setting, although in-area placements had a greater number of advantages than out-of-area placements. Unexpectedly, out-of-area placements had lower total costs, accommodation costs and daytime activity costs.

CONCLUSIONS

No overall conclusion could be reached about cost-effectiveness. A number of potential reasons for the differences in cost were identified. Although additional resources may be needed to provide in-area services for those currently placed out-of-area, government policy to provide comprehensively for those who want to live locally, irrespective of their needs, appears to be attainable.

UV disinfection of wastewater flocs: the effect of secondary treatment conditions

Activated sludge flocs that are carried to the final effluent can significantly decrease the effectiveness of ultraviolet (UV) disinfection of wastewater. This effect is detected in a typical UV dose-response curve, where at higher UV doses there is a decrease in the inactivation rate (tailing). In this study, the effect of activated sludge process conditions on the UV inactivation kinetics of flocs was investigated. The conditions compared were nitrifying vs. non-nitrifying vs. an enhanced biological nutrient removal-University of Cape Town (BNR-UCT) system. The results showed that the flocs generated in the BNR-UCT process were easier to disinfect. The final effluent from the BNR-UCT process also showed improved kinetics of inactivation and reached higher levels of disinfection. The nitrifying system's final effluent had a lower number of initial fecal coliforms, which contributed to reaching higher disinfection levels compared to the non-nitrifying system.

Kinetics of UV inactivation of wastewater bioflocs

Ultraviolet disinfection is a physical method of disinfecting secondary treated wastewaters. Bioflocs formed during secondary treatment harbor and protect microbes from exposure to ultraviolet (UV) light, and significantly decrease the efficiency of disinfection at high UV doses causing the tailing phenomena. However, the exact mechanism of tailing and the role of biofloc properties and treatment conditions are not widely understood. It is hypothesized that sludge bioflocs are composed of an easily disinfectable loose outer shell, and a physically stronger compact core inside that accounts for the tailing phenomena. Hydrodynamic shear stress was applied to the bioflocs to peel off the looser outer shell to isolate the cores. Biofloc and core samples were fractionated into narrow size distributions by sieving and their UV disinfection kinetics were determined and compared. The results showed that for bioflocs, the tailing level elevates as the biofloc size increases, showing greater resistance to disinfection. However, for the cores larger than 45μm, it was found that the UV inactivation curves overlap, and show very close to identical inactivation kinetics. Comparing bioflocs and cores of similar size fraction, it was found that in all cases cores were harder to disinfect with UV light, and showed a higher tailing level. This study suggests that physical structure of bioflocs plays a significant role in the UV inactivation kinetics.

Effect of calcium on moving-bed biofilm reactor biofilms

The effect of calcium concentration on the biofilm structure, microbiology, and treatment performance was evaluated in a moving-bed biofilm reactor. Three experiments were conducted in replicate laboratory-scale reactors to determine if wastewater calcium is an important variable for the design and optimization of these reactors. Biofilm structural properties, such as thickness, oxygen microprofiles, and the composition of extracellular polymeric substances (EPS) were affected by increasing calcium concentrations. Above a threshold concentration of calcium between 1 and 50 mg/L, biofilms became thicker and denser, with a shift toward increasingly proteinaceous EPS at higher calcium concentrations up to 200 mgCa2+/L. At 300 mgCa2+/L, biofilms were found to become primarily composed of inorganic calcium precipitates. Microbiology was assessed through microscopy, denaturing grade gel electrophoresis, and enumeration of higher organisms. Higher calcium concentrations were found to change the bacterial community and promote the abundant growth of filamentous organisms and various protazoa and metazoan populations. The chemical oxygen demand removal efficiency was improved for reactors at calcium concentrations of 50 mg/L and above. Reactor effluents for the lowest calcium concentration (1 mgCa2+/L) were found to be turbid (>50 NTU), as a result of the detachment of small and poorly settling planktonic biomass, whereas higher concentrations promoted settling of the suspended phase. In general, calcium was found to be an important variable causing significant changes in biofilm structure and reactor function.

Alkaline extraction of wastewater activated sludge biosolids

Activated sludge produced by wastewater treatment facilities are a sub-utilized by-product whose handling and disposal represent significant costs to these facilities. In this work, we introduced a simple and effective alkaline extraction technique that extracts up to 75% of the sludge's organic matter into a liquor containing potentially useful organic material (proteins, carbohydrates, etc.). The results suggest that at pH 11 and above, cell lysis occurs, liberating substantial quantities of organic material into the alkaline solution. When compared to a cation exchange resin (CER) extraction developed for analytical purposes, the alkaline extraction recovered 3x more organic material. The alkaline extract was highly surface active, despite containing a relatively small fraction of lipids. At pH 12 and above the lipid fraction was enriched with C15-C16 fatty acid residues, likely associated with cell membrane phospholipids as suggested by nuclear magnetic resonance spectroscopy ((31)P NMR). Size exclusion chromatography studies show that the extract is enriched with biopolymers or assemblies of molecular weights in the order of tens of thousands of Daltons. Potential uses for the extract are discussed.

Growth kinetics of Hyphomicrobium and Thiobacillus spp. in mixed cultures degrading dimethyl sulfide and methanol

The growth kinetics of Hyphomicrobium spp. and Thiobacillus spp. on dimethyl sulfide (DMS) and methanol (in the case of Hyphomicrobium spp.) in an enrichment culture created from a biofilter cotreating DMS and methanol were studied. Specific growth rates of 0.099 h(-1) and 0.11 h(-1) were determined for Hyphomicrobium spp. and Thiobacillus spp., respectively, growing on DMS at pH 7. These specific growth rates are double the highest maximum specific growth rate for bacterial growth on DMS reported to date in the literature. When the pH of the medium was decreased from pH 7 to pH 5, the specific growth rate of Hyphomicrobium spp. decreased by 85%, with a near 100-fold decline in the yield of Hyphomicrobium 16S rRNA gene copies in the mixed culture. Through the same pH shift, the specific growth rate and 16S rRNA gene yield of Thiobacillus spp. remained similar. When methanol was used as a substrate, the specific growth rate of Hyphomicrobium spp. declined much less over the same pH range (up to 30%) while the yield of 16S rRNA gene copies declined by only 50%. Switching from an NH(4)(+)-N-based source to a NO(3)(-)-N-based source resulted in the same trends for the specific growth rate of these microorganisms with respect to pH. This suggests that pH has far more impact on the growth kinetics of these microorganisms than the nitrogen source. The results of these mixed-culture batch experiments indicate that the increased DMS removal rates observed in previous studies of biofilters cotreating DMS and methanol are due to the proliferation of DMS-degrading Hyphomicrobium spp. on methanol at pH levels not conducive to high growth rates on DMS alone.

Production and characterization of lignocellulosic biomass-derived activated carbon

The goal of this work is to establish the technical feasibility of producing activated carbon from pulp mill sludges. KOH chemical activation of four lignocellulosic biomass materials, two sludges from pulp mills, one sludge for a linerboard mill, and cow manure, were investigated experimentally, with a focus on the effects of KOH/biomass ratio (1/1, 1.5/1 and 2/1), activation temperature (400-600 °C) and activation time (1 to 2 h) on the development of porosity. The activation products were characterized for their physical and chemical properties using a surface area analyzer, scanning electron microscopy and Fourier transform infrared spectroscopy. Experiments were carried out to establish the effectiveness of the lignocellulosic biomass-derived activated carbon in removing methylene blue (MB), a surrogate of large organic molecules. The results show that the activated carbon are highly porous with specific surface area greater than 500 m²/g. The yield of activated carbon was greater than the percent of fixed carbon in the dry sludge, suggesting that the activation process was able to capture a substantial amount of carbon from the organic matter in the sludge. While 400 °C was too low, 600 °C was high enough to sustain a substantial rate of activation for linerboard sludge. The KOH/biomass ratio, activation temperature and time all play important roles in pore development and yield control, allowing optimization of the activation process. MB adsorption followed a Langmuir isotherm for all four activated carbon, although the adsorption capacity of NK-primary sludge-derived activated carbon was considerably lower than the rest, consistent with its lower specific surface area.

Anaerobic treatability and biogas production potential of selected in-mill streams

Biochemical methane potential assays (BMP assays) were performed to study the potential of anaerobic treatment of in-mill wastewaters. The assay results indicated that condensate and the BCTMP effluent, which are currently treated with the anaerobic internal circulation reactors, were the best streams for anaerobic treatment because of their relatively high degradability (>80%) and initial rates of biogas production. The softwood dewatering process stream was the worst with the lowest degradability (~30%). The hardwood stream was more degradable than the softwood stream from the same process. Biogas production was found to be additive and predictable in blended samples. In addition, degradability was found to be negatively correlated to the concentration of dehydroabietic acid and tannin-lignin compounds. The anaerobic treatment of the suitable streams has great potential value with significantly reduced sludge production and energy savings.

Mid-infrared doping tunable transmission through subwavelength metal hole arrays on InSb

Doping-tunable mid-infrared extraordinary transmission is demonstrated from a periodic metal hole array patterned on n-InSb. The polarization-dependent transmission was measured at room temperature and 77 K. In addition, the extraordinary transmission was measured for incident angles from 0 degrees to 35 degrees in 5 degrees steps. A fundamental resonance shift of approximately 123 cm-1 (1.4 microm) is observed by varying the doping from 1 x 10(16) to 2 x 10(18) cm(-3). The calculated transmission resonances were in good agreement with the experimental results. This suggests that InSb semiconductor-based plasmonic structures may be suitable for a variety of tunable mid-infrared device applications.

Modeling the biofiltration of dimethyl sulfide in the presence of methanol in inorganic biofilters at steady state

The presence of methanol (MeOH) improves DMS removal (up to 11-fold) by enhancing biomass growth in inorganic biofilters. Although the overall effect is positive, prolonged growth on methanol also negatively affects DMS degradation as a result of competition with DMS. The objectives of this study were to explore the potential to optimize DMS removal with methanol addition and to develop and experimentally validate a mathematical model describing the biofiltration of DMS in the presence of MeOH. Continuous experiments using three bench-scale biofilters packed with inorganic material were performed to examine the removal of DMS under different MeOH addition rates ranging from 0 to 140 g/m3/h. For a constant DMS loading of 3.5 g/m3/h, a maximum DMS removal rate of 1.8 g/m3/h was achieved at a MeOH addition rate of 20 g/m3/h in the inorganic biofilters. A steady-state model incorporating the competitive and activation effects of MeOH on DMS biodegradation was developed, and the modeled results on DMS and MeOH removal were in close agreement with experimental data. Both the experimental data and model simulation suggest that there is an optimum MeOH addition rate for a given DMS loading. A step-feeding strategy for MeOH addition was proposed and tested by the model to optimize DMS removal. The model-predicted results demonstrate that six-step feeding of MeOH enhances DMS treatment by 46% in the biofilters when compared to conventional feeding (one-step) of MeOH at the same total mass loading.

A diffraction-compensating 0-25 ns free space terahertz delay line for coherent quantum control

Free space delay lines provide pulses of variable time spacing for optical experiments such as pump-probe spectroscopy and coherent quantum control, including spin and photon echo techniques. However, in the terahertz region of the spectrum, beam divergence due to diffraction limits the useful length of traditional free space delay lines. We present a novel double-folded variable delay line for light in the frequency range 0.24-1.2 THz, which incorporates a symmetric arrangement of lenses whose spacing can be adjusted to compensate for diffraction at each delay. Scalable for use in other wavelength regimes, the design relays an input Gaussian beam waist to the output with up to 25 ns ( approximately 8 m) total delay and is enclosed in a desiccated volume of <0.5 m3. The delay line can deliver two or three pulses with relative amplitudes controlled via variable spacing silicon etalon beam splitters. Profiles of a 0.24 THz beam show good agreement with calculations at long delays, with insertion loss per delay stage of approximately 3 dB.

Activation of Ca(2+)-dependent protein kinase II during repeated contractions in single muscle fibres from mouse is dependent on the frequency of sarcoplasmic reticulum Ca(2+) release

AIM

To investigate the importance and contribution of calmodulin-dependent protein kinase II (CaMKII) activity on sarcoplasmic reticulum (SR) Ca(2+)-release in response to different work intensities in single, intact muscle fibres.

METHODS

CaMKII activity was blocked in single muscle fibres using either the inhibitory peptide AC3-I or the pharmacological inhibitor KN-93. The effect on tetanic force production and [Ca(2+)](i) was determined during work of different intensities. The activity of CaMKII was assessed by mathematical modelling.

RESULTS

Using a standard protocol to induce fatigue (50x 70 Hz, 350 ms duration, every 2 s) the number of stimuli needed to induce fatigue was decreased from 47 +/- 3 contractions in control to 33 +/- 3 with AC3-I. KN-93 was a more potent inhibitor, decreasing the number of contractions needed to induce fatigue to 15 +/- 3. Tetanic [Ca(2+)](i) was 100 +/- 11%, 97 +/- 11% and 67 +/- 11% at the end of stimulation in control, AC3-I and KN-93 respectively. A similar inhibition was obtained using a high intensity protocol (20x 70 Hz, 200 ms duration, every 300 ms). However, using a long interval protocol (25x 70 Hz, 350 ms duration, every 5 s) no change was observed in either tetanic [Ca(2+)](i) or force when inhibiting CaMKII. A mathematical model used to investigate the activation pattern of CaMKII suggests that there is a threshold of active CaMKII that has to be surpassed in order for CaMKII to affect SR Ca(2+) release.

CONCLUSION

Our results show that CaMKII is crucial for maintaining proper SR Ca(2+) release and that this is regulated in a work intensity manner.

Effects of transient temperature conditions on the divergence of activated sludge bacterial community structure and function

The effect of temperature fluctuations on bacterial community structure and function in lab-scale sequencing batch reactors treating bleached kraft mill effluent was investigated. An increase in temperature from 30 to 45 degrees C caused shifts in both bacterial community structure and function. Triplicate reactors were highly similar for 40 days following startup. After the temperature shift, their community structure and function started to diverge from each other and from the control. A multi-response permutation procedure confirmed that the variability in community structure between transient and control reactors were greater than that among the triplicate transient reactors. The fact that these disturbances manifest themselves in different ways in apparently identical reactors suggests a high degree of variability between replicate systems.

Predictors, costs and characteristics of out of area placement for people with intellectual disability and challenging behaviour

BACKGROUND

Out of area placements for people with challenging behaviour represent an expensive and often ineffective strategy for meeting the needs of this service user group.

METHODS

More than 800 agencies and service settings in a large area of South Wales were screened to identify children and adults with challenging behaviour against a number of defined operational criteria. Detailed data on identified individuals and the services they received were collected by interviewing key informants. Univariate and multivariate statistics were employed to identify predictors of out of area placement.

RESULTS

In total, 1458 people were identified. Full data were available for 901 participants, 97 of whom were placed out of area. Predictors of out of area placement included behaviours resulting in physical injury and exclusion from service settings, a history of formal detention under the mental health act, the presence of mental health problems, a diagnosis of autism and higher total score on the Adaptive Behaviour Scale. Out of area placements were typically of high cost, and associated with only limited evidence of improved service quality.

CONCLUSIONS

Identifying predictors for out of area placement can be used to highlight deficiencies in local services and individuals at increased risk of exclusion from local services.

Effect of methanol on pH and stability of inorganic biofilters treating dimethyl sulfide

The biofiltration of dimethyl sulfide (DMS) and other reduced sulfur compounds (RSC) results in acidification of biofilters due to the accumulation of the sulfuric acid in packing material. This may lead to a decrease in biofilter performance due to a drop in pH. Results obtained from continuous experiments using three bench-scale biofilters packed with inorganic material mixed with limestone show that methanol (MeOH) alleviates the pH drop and enhances the stability of biofilter performance and DMS removal. The pH drop in the biofilters treating DMS with MeOH is 4 fold slower than that in the control biofiler treating DMS only. For the biofilters with MeOH addition, the pH of the biofilters drops more gradually (0.044 pH units per day) when compared to the MeOH suspension periods when MeOH is not added (0.23 pH units per day). MeOH addition consumes oxygen and results in a lower conversion ratio of sulfide to sulfuric acid due to the formation of elemental sulfur, reducing acidification in the biofilters. Nitrification was found to be actively taking place in the control biofilter treating DMS without MeOH addition, contributing to the significant pH drop in the reactor. It is proposed that MeOH prevents acid production from nitrification likely by limiting oxygen and nutrients to nitrifying bacteria in the MeOH-fed biofilters.

High-temperature biotrickling filtration of hydrogen sulphide

Biofiltration of malodorous reduced sulphur compounds such as hydrogen sulphide has been confined to emissions that are at temperatures below 40 degrees C despite the fact that there are many industrial emissions (e.g. in the pulp and paper industry) at temperatures well above 40 degrees C. This paper describes our study on the successful treatment of hydrogen sulphide gas at temperatures of 40, 50, 60 and 70 degrees C using a microbial community obtained from a hot spring. Three biotrickling filter (BTF) systems were set up in parallel for a continuous run of 9 months to operate at three different temperatures, one of which was always at 40 degrees C as a mesophilic control and the other two were for exploring high-temperature operation up to 70 degrees C. The continuous experiment and a series of batch experiments in glass bottles (250 ml) showed that addition of glucose and monosodium glutamate enhanced thermophilic biofiltration of hydrogen sulphide gas and a removal rate of 40 g m(-3) h(-1) was achieved at 70 degrees C. We suggest that the glucose is acting as a carbon source for the existing microbial community in the BTFs, whereas glutamate is acting as a compatible solute. The use of such organic compounds to enhance biodegradation of hydrogen sulphide, particularly at high temperatures, has not been demonstrated to our knowledge and, hence, has opened up a range of possibilities for applying biofiltration to hot gas effluent.

Growth, structural, and optical properties of self-assembled (In,Ga)as quantum posts on GaAs

Self-assembled quantum dots embedded in semiconductor heterostructures have proved to be a rich system for exploring the physics of three dimensionally confined charges and excitons. We present here a novel structure, which allows adjusting the level of confinement between 3D and 2D for electrons and holes, respectively. The quantum post consists of a quantum dot connected to a short quantum wire. The molecular beam epitaxy deposition of these self-assembled structures is discussed, and their structural and chemical compositions are presented. Their optical properties measured by photoluminescence are compared to an eight-band strain-dependent k.p model incorporating detailed structure and alloy composition. The calculations show electron delocalization in the quantum wire part of the quantum post and hole localization in the strain-induced regions at the ends of the quantum post. The quantum post offers the possibility of controlling the dipole moment in the structure and opens up new means for tuning the intra-subband transitions by controlling its dimensions.

Multivariate statistical analysis of a high rate biofilm process treating kraft mill bleach plant effluent

This study reports on a multivariate analysis of the moving bed biofilm reactor (MBBR) wastewater treatment system at a Canadian pulp mill. The modelling approach involved a data overview by principal component analysis (PCA) followed by partial least squares (PLS) modelling with the objective of explaining and predicting changes in the BOD output of the reactor. Over two years of data with 87 process measurements were used to build the models. Variables were collected from the MBBR control scheme as well as upstream in the bleach plant and in digestion. To account for process dynamics, a variable lagging approach was used for variables with significant temporal correlations. It was found that wood type pulped at the mill was a significant variable governing reactor performance. Other important variables included flow parameters, faults in the temperature or pH control of the reactor, and some potential indirect indicators of biomass activity (residual nitrogen and pH out). The most predictive model was found to have an RMSEP value of 606 kgBOD/d, representing a 14.5% average error. This was a good fit, given the measurement error of the BOD test. Overall, the statistical approach was effective in describing and predicting MBBR treatment performance.

Strategies for minimizing deflocculation of biosolids due to oxygen disturbances

The objective of this paper is to identify deflocculation under short-term disturbances of dissolved oxygen (DO) in a continuous system, and to explore the strategies for minimizing the carry-over of biosolids. Sludge deflocculation was examined in four parallel sequencing batch reactors (SBRs) fed with primary treated effluents from a bleached kraft pulp and paper mill. Results show that the DO transients caused a reduction of soluble COD (SCOD) removal efficiency by 50-70%, increases in suspended solid (SS) concentration and turbidity by more than 100%. Under the DO disturbances, the ratio of bulk Ca2+/K+ decreased by 10% in the treated effluents. All these changes were reversible within 24 hrs after the DO concentrations were restored up to 4 mg/L, indicating a physicochemical response of microorganisms to the DO transients. The sludge deflocculation is correlated with the decreasing ratio of Ca2+ to K+ in the extracellular environment. Addition of calcium chloride, tetraethylammonium chloride or glibenclamide promotes the formation of bioflocs bigger than 12.5 microm, but the deflocculation of biosolids under the DO transients wasn't completely prevented.