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Background Despite its high market potential, bio-based succinic acid production experienced recently a declining trend because the initial investments did not meet the expectations for rapid market growth. Thus, reducing the succinic acid production cost is imperative to ensure industrial implementation. Results Succinic acid production has been evaluated using hydrolysates from the organic fraction of municipal solid waste (OFMSW) collected from MSW treatment plants. A tailor-made enzymatic cocktail was used for OFMSW hydrolysate production containing up to 107.3 g/L carbon sources and up to 638.7 mg/L free amino nitrogen. The bacterial strains Actinobacillus succinogenes and Basfia succiniciproducens were evaluated for succinic acid production with the latter strain being less efficient due to high lactic acid production. Batch A. succinogenes cultures supplemented with 5 g/L yeast extract and 5 g/L MgCO3 reached 29.4 g/L succinic acid with productivity of 0.89 g/L/h and yield of 0.56 g/g. Continuous cultures at dilution rate of 0.06 h−1 reached 21.2 g/L succinic acid with yield of 0.47 g/g and productivity of 1.27 g/L/h. Downstream separation and purification of succinic acid was achieved by centrifugation, treatment with activated carbon, acidification with cation exchange resins, evaporation and drying, reaching more than 99% purity. Preliminary techno-economic evaluation has been employed to evaluate the profitability potential of bio-based succinic acid production. Conclusions The use of OFMSW hydrolysate in continuous cultures could lead to a minimum selling price of 2.5 $/kg at annual production capacity of 40,000 t succinic acid and OFMSW hydrolysate production cost of 25 $/t sugars.

Waste management and declining soil fertility are the two main issues experienced by all developing nations, like India. Nowadays, agricultural utilization of Municipal Solid Waste (MSW) is one of the most promising and cost effective options for managing solid waste. It is helpful in solving two current burning issues viz. soil fertility and MSW management. However, there is always a potential threat because MSW may contain pathogens and toxic pollutants. Therefore, much emphasis has been paid to composting of MSW in recent years. Application of compost from MSW in agricultural land helps in ameliorating the soil’s physico-chemical properties. Apart from that it also assists in improving biological response of cultivated land. Keeping the present situation in mind, this review critially discusses the current scenario, agricultural utilization of MSW compost, role of soil microbes and soil microbial response on municipal solid waste compost application.

Municipal solid waste (MSW) generation rate is on the rise as it is estimated to reach 3,539 million tonnes by 2050 from the 1,999 million tonnes in 2015. The seasonal variations of the physio-chemical properties of the MSW among others exacerbates its management challenges. This study aimed to conduct in-depth investigations on the seasonal variations of physio-chemical properties of the MSW generated in Kabale Municipality, southwestern Uganda to inform sustainable MSW management systems. This study revealed that this MSW is majorly plastics, with concentrations of 21.45% and 26.94% in the dry and wet seasons, respectively, which presents a more recycling potential for these plastics in the wet season. The biodegradable MSW fraction (food, paper, cardboard and garden trimming wastes), which were 35.6% and 35.34% for the dry and wet seasons, respectively, supports energy recovery from the waste in the form of biogas, with a higher potential in the wet season as supported by its higher volatile solid content for the same of 48.92% as compared to that of the dry season of 34.92%. Based on these findings, it is recommended among others that the masses be sensitized on how to generate biogas from the biodegradable fraction of this MSW.

Background and aims Besides general effect of organic residues on soil quality and plant crop, hormonal direct effect on plant growth by extracted humic acids of organic materials is interesting and profitable theme. In the present work, we studied on direct interaction between humic acid and root growth, depending on different origin of organic materials. Methods All extracted humic acids of four organic materials (sewage sludge, compost sewage sludge, municipal solid waste, compost municipal solid waste) were characterized chemically by elemental analyses, ion pair chromatography (ICP), size exclusion chromatography (HPSEC), solid-state nuclear magnetic resonance (13C-CPMAS-NMR) and quantification of IAA. Later, different morphological effects on maize (principal root growth, lateral root growth, root area, root mitosic site, root dry weight and H+-ATPase activity of plasma membrane) were analyzed. Results All humic acids samples promoted root growth and proton pump activity in maize vesicles, especially those composted samples, which contained more carboxylic groups and had a more hydrophobic character, produced preferentially morphological and biochemical effects.

Due to the increase in the generation of municipal solid waste and its impact on the environment and health, governments have been overburdened by its impact. Therefore, they have developed initiatives for waste disposal options in which citizens are involved. For that reason, this article aims to identify the population sector that participates in the separation of municipal solid waste and goes to the collection centers, as well as to characterize waste in three points known as Reciclacentros in the city of Hermosillo, Sonora. For this purpose, surveys were applied, selecting the respondents in a non-probabilistic way. In the characterization, the amount of waste received at each point was weighed. The data obtained were analyzed through a non-parametric Kruskal - Wallis test with 95% confidence (p<0.05). It was found that the people going to the Reciclacentros have an average monthly income of more than 30 thousand Mexican pesos, mostly young adult women between 25 and 44 years old, with the highest participation. In addition, the collection center identified as R3 presented a significantly higher difference in waste received with respect to the other collection centers in the period evaluated (23 t). Cardboard and paper, plastic, and glass are the most recovered waste in the city.

Background Worldwide 3.4 billion tonnes of municipal solid waste (MSW) will be produced annually by 2050, however, current approaches to MSW management predominantly involve unsustainable practices like landfilling and incineration. The organic fraction of MSW (OMSW) typically comprises ~ 50% lignocellulose-rich material but is underexplored as a biomanufacturing feedstock due to its highly inconsistent and heterogeneous composition. This study sought to overcome the limitations associated with studying MSW-derived feedstocks by using OMSW produced from a realistic and reproducible MSW mixture on a commercial autoclave system. The resulting OMSW fibre was enzymatically hydrolysed and used to screen diverse microorganisms of biotechnological interest to identify robust species capable of fermenting this complex feedstock. Results The autoclave pre-treated OMSW fibre contained a polysaccharide fraction comprising 38% cellulose and 4% hemicellulose. Enzymatic hydrolysate of OMSW fibre was high in d -glucose (5.5% w/v) and d -xylose (1.8%w/v) but deficient in nitrogen and phosphate. Although relatively low levels of levulinic acid (30 mM) and vanillin (2 mM) were detected and furfural and 5-hydroxymethylfurfural were absent, the hydrolysate contained an abundance of potentially toxic metals (0.6% w/v). Hydrolysate supplemented with 1% yeast extract to alleviate nutrient limitation was used in a substrate-oriented shake-flask screen with eight biotechnologically useful microorganisms ( Clostridium saccharoperbutylacetonicum , Escherichia coli , Geobacillus thermoglucosidasius , Pseudomonas putida , Rhodococcus opacus , Saccharomyces cerevisiae , Schizosaccharomyces pombe and Zymomonas mobilis ). Each species’ growth and productivity were characterised and three species were identified that robustly and efficiently fermented OMSW fibre hydrolysate without significant substrate inhibition: Z. mobilis , S. cerevisiae and R. opacus , respectively produced product to 69%, 70% and 72% of the maximum theoretical fermentation yield and could theoretically produce 136 kg and 139 kg of ethanol and 91 kg of triacylglycerol (TAG) per tonne of OMSW. Conclusions Developing an integrated biorefinery around MSW has the potential to significantly alleviate the environmental burden of current waste management practices. Substrate-oriented screening of a representative and reproducible OMSW-derived fibre identified microorganisms intrinsically suited to growth on OMSW hydrolysates. These species are promising candidates for developing an MSW biorefining platform and provide a foundation for future studies aiming to valorise this underexplored feedstock.

Background The start-up of the Turin municipal solid waste incineration plant (2013) was accompanied by surveillance of health effects, which included a human biomonitoring campaign. Here we present the results of the risk perception survey of local residents before the plant went into operation. Methods The survey sample was 394 local residents: 198 residing near the plant (exposed group) and 196 residing in an area distant from the plant site (unexposed group). The survey questionnaire investigated awareness of environmental and health issues, including a section on the perception of environmental health risks. Multivariate Poisson regressions were performed to determine the differences in risk perception between the two groups (exposed vs. unexposed). Results The exposed group was more concerned about natural hazards (prevalence ratio [PR] 1.61; 95% confidence interval [CI] 0.99–2.61), anthropogenic hazards (PR 1.35; 95% CI 1.03–1.77), and waste management (PR 1.19; 95% CI 0.94–1.50). There were no significant differences in opinions about environmental pollution-related diseases between the two groups, though the exposed considered themselves to be at risk for developing these diseases. The survey population placed its trust more in health care providers than in any other category. Conclusions The risk perception survey questionnaire yielded data that enabled a better understanding and interpretation of the social context: residents living near the incineration plant were more concerned than those living distant from it, especially about anthropogenic hazards. This information was subsequently incorporated into the design the communication tools.

Every year, many religious events attended by 300 million pilgrims take place in many holy cities and sites around the world. However, research on municipal solid waste is limited despite the reputation of religious events to generate substantial amounts of waste. This research aims to address this gap and contribute to new knowledge on municipal solid waste management at religious events by investigating and evaluating the municipal solid waste management system applied at the Arba’een event in Kerbala, one of the largest religious events in Iraq. Field observations and in-depth interviews with nine senior managers from Kerbala’s municipalities were conducted during the event in 2016, to develop an overall picture of the municipal solid waste management system applied during the event. The data were analysed using thematic analysis and fed to the ‘Wasteaware’ benchmark indicators framework to evaluate the performance of the event system. The results indicated that the system suffers from operational and governance weaknesses. Despite a focus on municipal solid waste collection and transportation, the collection coverage is only ~ 70%. There is no controlled landfill site in Kerbala. It is estimated that currently ~ 5% of the event municipal solid waste is recycled by informal recyclers: there is no formal recycling scheme. Kerbala does not perform well regarding governance. The inclusivity of providers and users of the municipal solid waste management services is minimal during the event, as the majority of stakeholders are not included in decision-making processes. Municipal solid waste management services are delivered free of charge, thus significantly influencing the financial sustainability of the system. This study recommends that MSW recycling should be encouraged through integrating the informal sector, improving public awareness and introducing a formal recycling scheme to make the event municipal solid waste management system effective and financially sustainable.

Delhi generates about 8360 tons of municipal solid waste per day, and there is low compliance to rules regarding waste management. The objective of this paper was to understand the situation in Delhi with respect to the segregation, storage, collection, and disposal of household waste, and to assess the knowledge of the residents of Delhi, and their willingness to engage in solid-waste management. A stratified random sample, comprising 3047 respondents, was chosen for a questionnaire survey, covering all municipalities of Delhi, with socio-economic classification as the stratifying variable. Survey results indicate that 60% of residents do not know the difference between biodegradable and non-biodegradable waste, and only 2% of them segregate waste. Fifty-eight percent of respondents reported that the waste collector mixes the segregated waste, 97% of respondents reported that they sold items to an itinerant waste buyer, and 87% of households are covered by doorstep waste collection services. Abstract knowledge (general knowledge about waste management) is seen to have a significant correlation with willingness to engage in waste management. Differences between the socio-economic groups indicate that the highest (most educated and wealthy), as well as the lowest socio-economic category (least educated and poor), older age-groups, and women, have greater abstract knowledge. Socio-economic categories having higher abstract knowledge can be active participants in decentralized models of waste management.

In this study, the feasibility of integrating microalgae cultivation in a biogas production process that treats the organic fraction of municipal solid waste (OFMSW) was investigated. In particular, the biomass growth performances in the liquid fraction of the digestate, characterized by high ammonia concentrations and turbidity, were assessed together with the nutrient removal efficiency. Preliminary laboratory-scale experiments were first carried out in photobioreactors operating in a continuous mode (Continuous-flow Stirred-Tank Reactor, CSTR), to gain preliminary data aimed at aiding the subsequent scaling up to a pilot scale facility. An outdoor experimental campaign, operated from July to October 2019, was then performed in a pilot scale raceway pond (4.5 m2), located in Arzignano (VI), Italy, to assess the performances under real environmental conditions. The results show that microalgae could grow well in this complex substrate, although dilution was necessary to enhance light penetration in the culture. In outdoor conditions, nitrification by autotrophic bacteria appeared to be significant, while the photosynthetic nitrogen removal was around 12% with respect to the inlet. On the other hand, phosphorus was almost completely removed from the medium under all the conditions tested, and a biomass production between 2–7 g m−2 d−1 was obtained.