Municipal solid waste management challenges in developing regions: A comprehensive review and future perspectives for Asia and Africa

The rapid urbanization witnessed in developing countries in Asia and Africa has led to a substantial increase in municipal solid waste (MSW) generation. However, the corresponding disposal strategies, along with constraints in land resources and finances, compounded by unorganized public behaviour, have resulted in ineffective policy implementation and monitoring. This lack of systematic and targeted orientation, combined with blind mapping, has led to inefficient development in many areas. This review examines the key challenges of MSW management in developing countries in Asia and Africa from 2013 to 2023, drawing insights from 170 academic papers. Rather than solely focusing on recycling, the study proposes waste sorting at the source, optimization of landfill practices, thermal treatment measures, and strategies to capitalize on the value of waste as more pertinent solutions aligned with local realities. Barriers to optimizing management systems arise from socio-economic factors, infrastructural limitations, and cultural considerations. The review emphasizes the importance of integrating the study area into the circular economy framework, with a focus on enhancing citizen participation in solid waste reduction and promoting recycling initiatives, along with seeking economic assistance from international organizations.

Artificial intelligence for waste management in smart cities: a review

The rising amount of waste generated worldwide is inducing issues of pollution, waste management, and recycling, calling for new strategies to improve the waste ecosystem, such as the use of artificial intelligence. Here, we review the application of artificial intelligence in waste-to-energy, smart bins, waste-sorting robots, waste generation models, waste monitoring and tracking, plastic pyrolysis, distinguishing fossil and modern materials, logistics, disposal, illegal dumping, resource recovery, smart cities, process efficiency, cost savings, and improving public health. Using artificial intelligence in waste logistics can reduce transportation distance by up to 36.8%, cost savings by up to 13.35%, and time savings by up to 28.22%. Artificial intelligence allows for identifying and sorting waste with an accuracy ranging from 72.8 to 99.95%. Artificial intelligence combined with chemical analysis improves waste pyrolysis, carbon emission estimation, and energy conversion. We also explain how efficiency can be increased and costs can be reduced by artificial intelligence in waste management systems for smart cities.

Microplastic sources, formation, toxicity and remediation: a review

Microplastic pollution is becoming a major issue for human health due to the recent discovery of microplastics in most ecosystems. Here, we review the sources, formation, occurrence, toxicity and remediation methods of microplastics. We distinguish ocean-based and land-based sources of microplastics. Microplastics have been found in biological samples such as faeces, sputum, saliva, blood and placenta. Cancer, intestinal, pulmonary, cardiovascular, infectious and inflammatory diseases are induced or mediated by microplastics. Microplastic exposure during pregnancy and maternal period is also discussed. Remediation methods include coagulation, membrane bioreactors, sand filtration, adsorption, photocatalytic degradation, electrocoagulation and magnetic separation. Control strategies comprise reducing plastic usage, behavioural change, and using biodegradable plastics. Global plastic production has risen dramatically over the past 70 years to reach 359 million tonnes. China is the world's top producer, contributing 17.5% to global production, while Turkey generates the most plastic waste in the Mediterranean region, at 144 tonnes per day. Microplastics comprise 75% of marine waste, with land-based sources responsible for 80-90% of pollution, while ocean-based sources account for only 10-20%. Microplastics induce toxic effects on humans and animals, such as cytotoxicity, immune response, oxidative stress, barrier attributes, and genotoxicity, even at minimal dosages of 10 μg/mL. Ingestion of microplastics by marine animals results in alterations in gastrointestinal tract physiology, immune system depression, oxidative stress, cytotoxicity, differential gene expression, and growth inhibition. Furthermore, bioaccumulation of microplastics in the tissues of aquatic organisms can have adverse effects on the aquatic ecosystem, with potential transmission of microplastics to humans and birds. Changing individual behaviours and governmental actions, such as implementing bans, taxes, or pricing on plastic carrier bags, has significantly reduced plastic consumption to 8-85% in various countries worldwide. The microplastic minimisation approach follows an upside-down pyramid, starting with prevention, followed by reducing, reusing, recycling, recovering, and ending with disposal as the least preferable option.

Strategies to save energy in the context of the energy crisis: a review

New technologies, systems, societal organization and policies for energy saving are urgently needed in the context of accelerated climate change, the Ukraine conflict and the past coronavirus disease 2019 pandemic. For instance, concerns about market and policy responses that could lead to new lock-ins, such as investing in liquefied natural gas infrastructure and using all available fossil fuels to compensate for Russian gas supply cuts, may hinder decarbonization efforts. Here we review energy-saving solutions with a focus on the actual energy crisis, green alternatives to fossil fuel heating, energy saving in buildings and transportation, artificial intelligence for sustainable energy, and implications for the environment and society. Green alternatives include biomass boilers and stoves, hybrid heat pumps, geothermal heating, solar thermal systems, solar photovoltaics systems into electric boilers, compressed natural gas and hydrogen. We also detail case studies in Germany which is planning a 100% renewable energy switch by 2050 and developing the storage of compressed air in China, with emphasis on technical and economic aspects. The global energy consumption in 2020 was 30.01% for the industry, 26.18% for transport, and 22.08% for residential sectors. 10-40% of energy consumption can be reduced using renewable energy sources, passive design strategies, smart grid analytics, energy-efficient building systems, and intelligent energy monitoring. Electric vehicles offer the highest cost-per-kilometer reduction of 75% and the lowest energy loss of 33%, yet battery-related issues, cost, and weight are challenging. 5-30% of energy can be saved using automated and networked vehicles. Artificial intelligence shows a huge potential in energy saving by improving weather forecasting and machine maintenance and enabling connectivity across homes, workplaces, and transportation. For instance, 18.97-42.60% of energy consumption can be reduced in buildings through deep neural networking. In the electricity sector, artificial intelligence can automate power generation, distribution, and transmission operations, balance the grid without human intervention, enable lightning-speed trading and arbitrage decisions at scale, and eliminate the need for manual adjustments by end-users.

Seaweed for climate mitigation, wastewater treatment, bioenergy, bioplastic, biochar, food, pharmaceuticals, and cosmetics: a review

The development and recycling of biomass production can partly solve issues of energy, climate change, population growth, food and feed shortages, and environmental pollution. For instance, the use of seaweeds as feedstocks can reduce our reliance on fossil fuel resources, ensure the synthesis of cost-effective and eco-friendly products and biofuels, and develop sustainable biorefinery processes. Nonetheless, seaweeds use in several biorefineries is still in the infancy stage compared to terrestrial plants-based lignocellulosic biomass. Therefore, here we review seaweed biorefineries with focus on seaweed production, economical benefits, and seaweed use as feedstock for anaerobic digestion, biochar, bioplastics, crop health, food, livestock feed, pharmaceuticals and cosmetics. Globally, seaweeds could sequester between 61 and 268 megatonnes of carbon per year, with an average of 173 megatonnes. Nearly 90% of carbon is sequestered by exporting biomass to deep water, while the remaining 10% is buried in coastal sediments. 500 gigatonnes of seaweeds could replace nearly 40% of the current soy protein production. Seaweeds contain valuable bioactive molecules that could be applied as antimicrobial, antioxidant, antiviral, antifungal, anticancer, contraceptive, anti-inflammatory, anti-coagulants, and in other cosmetics and skincare products.

Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review

In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and enhances microbial activity. Co-composted biochar improves soil properties and enhances crop productivity. Pristine and engineered biochar can also be employed for water and soil remediation to remove pollutants. In construction, biochar can be added to cement or asphalt, thus conferring structural and functional advantages. Incorporating biochar in biocomposites improves insulation, electromagnetic radiation protection and moisture control. Finally, synthesising biochar-based materials for energy storage applications requires additional functionalisation.

Potential of biogas production from manure of dairy cattle fed on natural soil supplement rich in iron under batch and semi-continuous anaerobic digestion

This study provides a novel method for improving the anaerobic digestion (AD) of Holstein dairy manure (HDM) by the direct addition of Mineraso (MnS), a natural soil-derived supplement, to the feed of Holstein dairy cattle (HDC). MnS is chiefly composed of approximately 69.08% Fe₃O₄ and was supplemented at rates of 0 (F1), 25 (F2), and 50 (F3) g/head of HDC/d for two months. The HDM was then examined for non-absorbed iron prior to the batch and semi-continuous bench AD experiments. The results revealed that MnS enhanced CH₄ generation in F2 and F3 by 25% and 42%, respectively, in the batch experiments compared to that of F1. Additionally, the gas yield improved in F2 and F3 by 45% and 66%, respectively, over the control after 7 d in the bench experiments. Therefore, supplementing animals with MnS represents a sustainable and economic approach to enhancing CH₄ yields.

Prospects for biogas production and H2S control from the anaerobic digestion of cattle manure: The influence of microscale waste iron powder and iron oxide nanoparticles

Improving the quality and quantity of biogas usually requires pre-treatment to maximize methane yields and/or post-treatment to remove H₂S, which involves considerable energy consumption and higher costs. Therefore, this study proposes a cost-effective method for the enhanced anaerobic digestion (AD) of dairy manure (DM) without pre/post-treatment by directly adding waste iron powder (WIP) and iron oxide nanoparticles (INPs) to batch digesters. The results showed that the addition of iron in the form of microscale WIP (generated from the laser cutting of iron and steel) at concentrations of 100 mg/L, 500 mg/L, and 1000 mg/L improved methane yields by 36.99%, 39.36%, and 56.89%, respectively. In comparison, the equivalent dosages of INPs improved yields by 19.74%, 18.14%, and 21.11%, respectively. Additionally, the highest WIP dose (1000 mg/L) achieved the maximum improvement in the rate of hydrolysis (k), which was 1.25 times higher than in control reactions, and a maximum biomethane production rate (R_max) of 0.045 L/gVS/d according to kinetic analysis models (i.e., first-order and the Gompertz kinetic models). The rate of H₂S production was also significantly reduced (by 45.20%, 58.16%, and 77.24%) using the three WIP concentrations in comparison with INPs (which achieved reductions of 33.59%, 46.30%, and 53.52%, respectively). Therefore, the direct mixing of WIP with cattle manure is proposed as a practical and economical means of addressing complex and high-cost pre- and post-treatments that are otherwise required in the digestion process.

Antiprotozoal activity of silver nanoparticles against Cryptosporidium parvum oocysts: New insights on their feasibility as a water disinfectant

Cryptosporidium is a protozoan of extremely medical and veterinary impact; whose oocysts donate a considerable resistant to the water treatment processes. Therefore, this study aimed to explore the impacts of silver nanoparticles (AgNPs) on count and viability of the Cryptosporidium parvum (CP) isolated from different tap water samples. The oocysts were exposed to AgNPs at different dosages of 0.05, 0.1 and 1 ppm for several contact times (30 min to 4 h). The results showed a significant decrease in oocyst count and viability in a dose-dependent manner. Additionally, AgNPs at a conc. of 1 ppm for 30 min and 0.1 ppm for 1 h reduced the oocysts by 97.2 and 94.4%, respectively. Comparatively, there was a noticeable increase in the oocyst's viability at 2 and 4 h, which emphasized that the time of contact between AgNPs and CP was not a major influencing factor for successful application of AgNPs in the nano-water treatment.

Impacts of iron oxide and titanium dioxide nanoparticles on biogas production: Hydrogen sulfide mitigation, process stability, and prospective challenges

Anaerobic digestion for biogas production is one of the most used technology for bioenergy. However, the adoption of nanoparticles still needs further studies. Therefore, this study was designed to examine the effect of metal oxide nanoparticles (MONPs) at four different concentrations in two different combinations, 20 (R1) and 100 (R2) mg/L for Fe₂O₃, 100 (R3) and 500 (R4) mg/L for TiO₂, and a mixture of Fe₂O₃ and TiO₂ at rates of 20, 500 (R5) and 100, and 500 (R6), on hydrogen sulfide (H₂S) mitigation, biogas, and methane (CH₄) yield during the anaerobic digestion of cattle manure (CM) using an anaerobic batch system. The results showed that H₂S production was 2.13, 2.38, 2.37, 2.51, 2.64, and 2.17 times lower than that of the control (R0), respectively, when the CM was treated by the aforementioned MONPs. Additionally, biogas and CH₄ production were 1.09 and 1.105, 1.15 and 1.191, 1.07 and 1.097, 1.17 and 1.213, 1.10 and 1.133, and 1.13 and 1.15 times higher than those of R0 when R1, R2, R3, R4, R5, and R6 were supplemented with MONPs, respectively. The highest specific production of biogas and CH₄ was 336.25 and 192.31 mL/gVS, respectively, which was achieved by R4 supplemented with 500 mg/L TiO₂ NPs, while the corresponding values in the case of R0 were 286.38 and 158.55 mL/gVS.

Complications associated with higher order compared to lower order cesarean sections

Background: The rate of multiple cesarean sections is persistently on the rise because of cultural demands for large families, and multiple cesarean sections are an important cause of maternal morbidity and mortality.Objectives: This study was designed to detect the complications associated with higher order compared to lower order cesarean sections.Materials and methods: The hospitals record of women who had a cesarean section performed after three or more previous cesarean sections, and those who had a cesarean section for the second time over 2 years reviewed. Women with ≥3 cesarean sections admitted for elective cesarean section after 38 weeks' gestation, and those with ≥3 cesarean sections admitted in labor for emergency cesarean section were included in group 1. Women with history of previous one lower segment cesarean section (LSCS), who refused trial of labor and women with one LSCS who had an emergency cesarean section after failed trial of labor (TOL) were included in group 2. Antenatal, intraoperative, and postoperative data were reviewed. Statistical analysis done using SPSS version 20 (Chicago, Illinois, USA), to detect the complications associated with higher order compared to lower order cesarean sections. Primary outcome measures; complications associated with higher order compared to lower order cesarean sections. Secondary outcome measures; intraoperative, and postoperative complications.Results: Four hundred and fifty (450) women undergoing repeat cesarean section studied; 32.2% (145/450) had ≥3 previous cesarean sections (group 1), and 67.8% (305/450) had previous one cesarean section (group 2). In group 1, 77.2% (112/145) had previous three cesarean sections, 12.4% (18/145) had previous four cesarean sections, 9% (13/145) had previous five cesarean sections, and 1.4% (2/145) had previous six cesarean sections. The proportion of unbooked admission, and emergency cesarean sections were significantly high in group 2 compared to group 1 (11.1% (34/305) and 73.1% (223/305) versus 4.83% (7/145) and 40.7% (59/145); respectively) (p<.05, 95% CI; 0.1-0.2) and p<.01, 95% CI; 0.4-11.4; respectively. The risk of dense omental adhesions, and bladder injuries were significantly high in group 1 compared to group 2 (4.14% (6/145) and 1.38% (2/145) versus 0.66% (2/305) and 0% (0/305); respectively), (p=.01 (95% CI; 0.6-1.6) and p=.01 (95% CI; 0.5-5.5); respectively). Logistic regression analysis showed that the bladder injury was 5 times more (odds ratio 5.0 (95% CI; 0.035-711.8)) and the blood transfusion was 4.7 times more (odds ratio 4.7 (95% CI; 0.147-151.5)) in women with >3 repeat cesarean sections compared to women with previous one cesarean section (insignificant difference p=.52 and .38; respectively).Conclusion: The risk of dense omental adhesions and bladder injury was significantly high in women with previous ≥3 cesarean sections compared to women with previous one cesarean section. Logistic regression analysis showed that the bladder injury was five times more and the blood transfusion was 4.7 times more in women with >3 repeat cesarean sections compared to women with previous one cesarean section (insignificant difference).

Outcome of the vaginal birth after cesarean section during the second birth order in West Kazakhstan

Background

Vaginal birth after cesarean section (VBAC) increases the chance of subsequent vaginal deliveries and reduces the repeat cesarean section (CS) rate with subsequent postoperative morbidity.

Objectives

To detect the outcome of VBAC during the second birth order in Aktobe region of West Kazakhstan.

Patients and Methods

A total of 832 women eligible for trial of VBAC were included in this study. Women who signed the consent of VBAC were evaluated thoroughly and data such as maternal age, body mass index, height, gestational age at admission, indication of the previous CS, estimated fetal weight, engagement of the fetal head, condition of the membranes, and cervical dilatation were collected. Data collected after delivery include duration from active phase of labor, mode of delivery, fetal, and neonatal outcomes. The collected data analyzed to detect the outcome of trial of VBAC during the second birth order in Aktobe region of West Kazakhstan.

Results

Logistic analysis and odds ratio (OR) showed that body mass index (BMI) ≤25 kg/m² (OR 1.7; P = 0.0004), height ≥150 cm (OR 1.7; P = 0.002), gestational age ≤40 weeks (OR 2.3; P = 0.0001), and inter-delivery interval ≥2 years (OR 1.6; P = 0.008) were significantly associated with successful VBAC. In addition, <2/5 of the fetal head palpable abdominally, station <-2 (OR 1.7; P = 0.0009), cervical dilatation ≥4 cm (OR 1.7; P = 0.003), and duration of active phase of labor ≤7 h (OR 1.6; P = 0.01) were significantly associated with successful VBAC.

Conclusion

VBAC is safe in properly selected cases. BMI ≤25 kg/m², gestational age ≤40 weeks, inter-delivery interval ≥2 years, and fetal head <-2 station increase the success of VBAC. Prolonged active phase of labor >7 h and the need for labor augmentation decrease the chance of VBAC success.

Delayed second twin delivery: benefits and risks

BACKGROUND

An increasing number of reports describe the delayed second twin delivery for days, or weeks with good results in the majority of the cases, and different survival rate between centers, without reported randomized controlled trials (RCTs).

OBJECTIVES

This study was designed to evaluate the suggested management of the delayed second twin delivery in the Sabah Maternity Hospital regarding its outcome, possible risks, and benefits.

PATIENTS AND METHODS

Forty-seven twin pregnancies with preterm labor (PTL) of the first fetus between 20-30 weeks, and delayed delivery of the second twin were included in this study. Studied women signed informed consent about the possible risks of keeping the live fetus in the hostile intrauterine environment, and benefits of the prolonged gestation for the second twin. Throughout the conservative treatment of the second twin, the studied women were hospitalized with regular follow up for infections, consumptive coagulopathy parameters, and wellbeing of the second twin.

RESULTS

There was significant difference in the gestational age at delivery between the first and second twin (22.6 ± 3.4 versus 34.3 ± 2.5 weeks; respectively, p = .01). There was significant difference in the birth weight between the first and second twin (435 ± 91.2 versus 1472 ± 61.5 g; respectively, p = .004). The rate of the cesarean delivery was significantly high during delivery of the second twin compared with the first twin (23.4% (11/47) versus 0% (0/47); respectively, p = .0001) with high survival rate for the second twin (85.1% (40/47)) after the delayed second twin delivery.

CONCLUSIONS

The birth weight, the gestational age, and the survival rate of the studied second twin significantly increased after the suggested management of the delayed second twin delivery.

Post-test probability for pulmonary embolism after ventilation-perfusion scan assessed by nuclear medicine physicians

OBJECTIVE

The objective of this prospective study was to compare assessments of pre- and post-ventilation-perfusion (V/Q) scan probabilities for pulmonary embolism (PE) by the nuclear medicine physician and the referring physician.

MATERIALS AND METHODS

Seventy-nine patients (41 females, 38 males, mean age 49 years) referred for V/Q scans over a period of 6 months and suspected of PE were included in the study. The pre-test likelihood was determined independently by a consultant nuclear physician and a referring physician prior to the V/Q scan. The scan was performed according to a standard protocol using 8 view technetium-99m diethylenetriamine pentaacetic acid aerosol ventilation study followed by a technetium-99m macroaggregated albumin perfusion study. The scan was interpreted according to prospective investigation of pulmonary embolism diagnosis criteria. The post-scan probability was calculated. The probability of PE was quoted as low, intermediate and high. Agreement or disagreement in assessing the pre- and post-scan probability was classified according to the degree of difference (no difference: 0; minor difference: 1, and major difference: 2 grades).

RESULTS

The agreement between the nuclear medicine and referring physicians on clinical probability of PE was moderate (63%) before the scan and good (90%) after the scan. The disagreement in assessing the clinical probability between the referring physician and the nuclear medicine physician was predominantly minor. Only 5 and 1% of the disagreement was major in pre-scan and post-scan probabilities, respectively.

CONCLUSION

The data show that nuclear medicine physicians can use the assessment of pre-scan clinical likelihood to determine the post-scan probability of PE.

National Immunization Coverage Survey Saudi Arabia, 1991

A nationwide survey was carried-out aiming at determination of immunization coverage level against the six killer diseases of childhood (tuberculosis, diphtheria, pertussis, tetanus, poliomyelitis, and measles). Variations between geographical zones, urban-rural settings, age, education and mother's employment, father's education, and child's birth order were studied. The standard WHO cluster technique was used. The sample (1102 children) was restricted to Saudi children 1-2 years old. Interviewers were exposed to training and methods of calibration, and involved in a pilot survey. Nationally, the survey showed very high coverage levels, BCG was the highest (99 per cent), measles was the lowest (90 per cent), whereas the three doses of DPT (diphtheria, pertussis and tetanus) and TOPV (trivalent oral polio vaccine) were in between (98, 96 and 94 per cent, respectively). There was no marked differences between urban-rural settings. The western zone showed the lowest coverage by all vaccines. The national coverage by the six vaccines reached 86 per cent correctly immunized (according to WHO standards), 14 per cent partially immunized and 1 per cent non-immunized. Immunization coverage was higher for children to younger mothers. The non-immunized group belonged exclusively to illiterate mothers (1 per cent). Children to mothers with basic education showed the highest coverage (88 per cent). Birth order had negative effect on coverage. Nationally, 88 per cent of children had immunization certificate while 12 per cent had not. The eastern and central zones had the highest percentages of children with certificates (92 and 91 per cent, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)