Municipal solid waste in developing countries mainly consists of degradable materials (>70%), which plays a significant role in GHG (Greenhouse gas) emissions in urban localities. The increasing ...municipal solid waste generation along with the high fraction of organic waste and its unscientific disposal is leading to emission of GHG (methane, CO2, etc.) in the atmosphere. Proportion of municipal solid wastes collected by the agencies disposed at identified sites is about 60%, while the balance is disposed-off at unauthorized disposal sites leading to the environmental consequences including greenhouse gas emissions. Mitigation strategy necessitates understanding of composition of waste for its treatment and management in an environmentally sound way. The study revealed that the per capita waste generated is about 91.01± 45.5g/day with the per capita organic waste generation of 74±35g/person/day. The household per capita waste generation was positively related with income and education levels, while negatively related with family (household) size. The organic fractions constitute 82% with the strong recovery potential and conversion to energy or compost range. The total organic waste generated is about 231.01 Gg/year and due to mismanagement consequent emissions are about 604.80 Gg/year. Integrated solid waste management strategy is suggested to manage the organic fractions through technology and policy interventions, which helps in mitigating GHG emissions with potential economic benefits.
Commercial mushrooms are produced on lignocellulose such as straw, saw dust, and wood chips. As such, mushroom-forming fungi convert low-quality waste streams into high-quality food. Spent mushroom ...substrate (SMS) is usually considered a waste product. This review discusses the applications of SMS to promote the transition to a circular economy. SMS can be used as compost, as a substrate for other mushroom-forming fungi, as animal feed, to promote health of animals, and to produce packaging and construction materials, biofuels, and enzymes. This range of applications can make agricultural production more sustainable and efficient, especially if the CO
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emission and heat from mushroom cultivation can be used to promote plant growth in greenhouses.
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•The Cu (II) and Pb (II) binding property of compost-derived DOM were investigated.•Alcohols, ethers and esters showed a preferential binding with Cu (II) and Pb(II).•Protein-like ...matter showed a preferential binding compared with humic-like matter.•The DOM showed higher binding affinities with Cu(II) compared with Pb(II).•The Cu(II) and Pb(II) binding ability of the DOM decreased after composting.
Three dissolved organic matter (DOM) samples were obtained from municipal solid wastes at the initial (C0), high-temperature (C7) and mature (C51) period during composting. Two-dimensional correlation spectroscopy (2D-COS) analysis on Fourier-transform infrared (FTIR), ultraviolet visible (UV–vis), and synchronous fluorescence spectra (SFS) were used to investigate the metal binding properties of compost-derived DOM. Synchronous and asynchronous maps of 2D-FTIR-COS of DOM-Cu(II) and DOM-Pb(II) were similar, however, the susceptibility and binding sequence of the corresponding spectral region was different. The N-H (amide I), phenolic OH, and C–O of alcohols, ethers, and esters were the most susceptive in the C0, C7, and C51 samples, respectively. 2D absorption COS indicated that the preferential binding with Cu(II) was shown to be at 305 nm for C0, at 236 nm for C7 and C51, and with Pb(II) at 247 nm for C0, at 233 nm for C7 and C51. 2D-SFS-COS indicated that protein-like matter showed a higher susceptibility and preferential binding with Cu(II) than humic-like substances. DOM showed a higher complexing affinity with Cu(II) than Pb(II) on the basis of the log K values. Spectral techniques combined with 2D-COS are useful to understand the binding heterogeneities of ligand sites within DOM-Cu(II) or Pb(II) during the composting.
•Diatomite added to manure composting promoted the organic matter transformation.•Diatomite improved nitrogen conservation and increased quality of compost.•Adding Diatomite amendment reduced CH4 and ...N2O emission.•Diatomite shortened the period of maturity reflected by germination index.
In order to investigate the improvement of Diatomite (DM) on the production of cleaner composting, reflected by emission of NH3 and greenhouse gases (GHGs), three dosages of DM (0%, 5% and 10%) were added into mixture of pig manure and sawdust for 42 days composting. Addition of DM promoted the transformation of organic matter and improved the quality of end product. Meanwhile, it was confirmed by the increase of NO3−-N formation and nitrogen conservation. Besides, adding DM aided on reducing emission of CH4, N2O and NH3 by 18.27%−30.41%, 26.89%−84.16% and 10.41%−23.70%, respectively. Furthermore, the DM had a positive effect on the maturity of compost products, reflecting by GI value and HA/FA. Consequently, through the factor analysis, 10% was suggested to improve the quality of end product and reduce nitrogen loss as well as GHGs emission.
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•Influence of biochar addition on nutrient transformation during composting.•Biochar addition improved the water-soluble nutrient contents during composting.•Higher dosage of biochar ...addition reduced the bioavailability of heavy metals.•Higher dosage of biochar addition reduced the maturity period.•150kgha−1 TKN compost amendments increased the Chinese cabbage biomass.
The influence of biochar amended dewatered fresh sewage sludge (DFSS)-wheat straw co-composting on nutrients transformation and end products quality was investigated. This is the first study to examine the biochar applied compost quality with different kgha−1 TKN on Brassica rapa L. growth. Seven mixtures were composted over 8-weeks period in 130-L reactor using the same DFSS with different concentration of biochar (2%, 4%, 6%, 8%, 12% and 18% on dry weight basis) and without additive added treatment served as control. The results indicated that compost with 8–12% biochar became more humified within 35days of composting, and the compost maturity parameters also showed that this could be much more feasible approach to increased water-soluble nutrients including NO3, DOC, DON, PO43−, K+ and Na+, but bioavailability of Cu, Zn, Ni and Pb content reduced as compared to control. Finally, results showed that 8–12% biochar was recommended for DFSS composting and 150kgha−1 TKN of compost dosages for organic farming.
•Utilization of food waste compost as an organic medium for microalgae cultivation.•Evaluation of microalgae growth and biochemical composition using organic medium.•Combination of up to 50% organic ...medium showed higher biomass yield.•Combination of up to 35% organic medium showed higher lipid and protein content.•Replacement of inorganic medium with organic medium is environmentally advantageous.
The present study investigates the prospective of substituting inorganic medium with organic food waste compost medium as a nutrient supplement for the cultivation of Chlorella vulgaris FSP-E. Various percentages of compost mixtures were replaced in the inorganic medium to compare the algal growth and biochemical composition. The use of 25% compost mixture combination was found to yield higher biomass concentration (11.1%) and better lipid (10.1%) and protein (2.0%) content compared with microalgae cultivation in fully inorganic medium. These results exhibited the potential of combining the inorganic medium with organic food waste compost medium as an effective way to reduce the cultivation cost of microalgae and to increase the biochemical content in the cultivated microalgae.
•The source separated collection and recycling of OFMSW are crucial processes for establishing sustainable waste management strategies.•Odor generation is the most challenging environmental factor ...for the sustainable management of composting plants.•Waste composting should be implemented in conjunction with source-separated collection to ensure the production of high-quality compost.•Quality-based compost classifications are recommended from the perspective of waste material recycling and environmental risk control.
Biodegradable material, primarily composed of food waste, accounts for 40–70wt% of municipal solid waste (MSW) in developing countries. Therefore, to establish a sustainable waste management system, it is essential to separate and recycle biodegradable organic material from the municipal waste stream. Of all the recycling methods, composting is recommended due to its environmental and economic benefits. However, compared with readily recyclable materials (e.g., paper, metals, etc.), recycling/composting biodegradable MSW presents a great challenge to furthering the promotion of waste recycling.
This review provides a systematic analysis of organic waste sorting and recycling/composting practices in several countries: the UK, US, Japan, and China. Compared to the great efforts that have been made in developed countries for the promotion of waste composting, much less has been achieved in developing countries. For example, the MSW composting rate in China decreased from 10% to less than 2% in the past 15 years, and similar trends may exist in other developing countries. Therefore, it is essential to identify the barriers that impede waste composting and predict developing trends. This article emphasizes environmental challenges (i.e., odor, bioaerosols, and heavy metals), focusing on their generation and control strategies, in an effort to identify barriers hindering MSW composting. Successful practices in several European countries suggest that source-separated composting presents many advantages over mechanical-separated composting. This may partially be ascribed to the fact that source separation of organic waste can prevent contact with heavy metal-bearing items, resulting in the production of high-quality compost. Mixed collection MSW normally contains significantly higher concentrations of heavy metals, which could affect the marketing of composting products. Moreover, source separation of organic waste can minimize waste pretreatment operations, leading to lower bioaerosol and malodor generation during composting. Implementing source separation of MSW in more countries would increase the amount of organic waste available for composting. In addition, attention should focus on secondary pollutant production for proper composting management. Finally, setting standards for end product quality control is highly recommended for controlling both marketing and environmental risks.
•Table FW has more putrescible fraction and fewer impurities than kitchen FW.•Three anaerobic digestion scenarios are compared with incineration practice.•AD followed by composting digestate is best ...in most of the impact categories.•AD followed by gasifying digestate outputs the largest electricity.•Gas engine emission, and water consumption should be lowered.
A life cycle assessment (LCA) was conducted to determine the best solution for dealing with the food waste (FW) generated in Singapore eateries. Since the representativeness of the life cycle inventory (LCI) data determined the overall quality of the LCA, this study made a significant endeavor to capture the local specificities, such as waste composition, water supply and treatment plant operation. Characterization data showed that eatery FW from Singapore contained 16% non-biodegradable impurities (such as plastic and metal) and a higher methane generation potential was found in FW from the dining table than in FW from the kitchen. Based on the FW chemical element composition, mass balances were established for the four examined scenarios, including incineration (Inci), anaerobic digestion (AD) followed by composting (ADcom), AD followed by incineration (ADinci) and AD followed by gasification (ADgas). Because of the environmental benefits from compost production in addition to electricity generation, ADcom outperformed other scenarios in all impact categories except Eutro (eutrophication), GW (global warming) and POC (photochemical ozone creation). The best score of GW was observed in ADgas, mainly ascribed to the highest electricity output and the carbon sequestration of biochar. The disadvantages of the AD scenarios in Eutro and POC were associated with NOx and CO emissions from the biogas engine. Finally, the sensitivity analysis demonstrated that better environmental profiles could be achieved if improvements can be made by minimizing water usage, mitigating gas engine pollution, and diverting as much FW as possible from incineration plants to AD plants. However, based on the local context, source separation was not an urgent issue for improving the sustainability of eatery FW management.
Spent mushroom compost biochar (SMCB) was prepared by carbonization and tested for the removal of heavy metals (Zn(II), Cu(II), and Pb(II)) by adsorption. The sorption of heavy metals was ...evaluated by studying several factors, such as the initial solution pH, contact time, temperature, and individual and competitive adsorption. Kinetic and equilibrium studies were carried out to determine the mechanism involved during adsorption. The Weber–Morris model demonstrated the significance of intraparticle diffusion on the adsorption process. In addition, thermodynamic studies showed that the process is endothermic and favorable, with good affinity of metals to the biochar. At last, SMCB was used as the adsorbent in a continuous fixed-bed column. The breakthrough curve was obtained for each heavy metal, and Thomas and Clark models were fitted. When all three metals coexisted in solution, competitive adsorption took place in both batch and continuous systems, showing that Pb has higher affinity to SMCB than Cu and Zn.
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•Thermo-tolerant actinomycetes were inoculated in different stages of composting.•Degradation of cellulose and enzymes activities were assessed during composting.•The structure of ...actinobacteria community were compared in different treatments.•The relationship between inoculation and formation of humic substances was analyzed.•A strategy for increasing content of humic substances and reducing CO2 emission.
The inoculum containing four cellulolytic thermophilic actinomycetes was screened from compost samples, and was inoculated into co-composting during different inoculation phases. The effect of different inoculation phases on cellulose degradation, humic substances formation and the relationship between inoculation and physical–chemical parameters was determined. The results revealed that inoculation at different phases of composting improved cellulase activities, accelerated the degradation of cellulose, increased the content of humic substances and influenced the structure of actinomycetic community, but there were significant differences between different inoculation phases. Redundancy analysis showed that the different inoculation phases had different impacts on the relationship between exogenous actinobacteria and physical–chemical parameters. Therefore, based on the promoting effort of inoculation in thermophilic phase of composting for the formation of humic substances, we suggested an optimized inoculation strategy to increase the content of humic substances, alleviate CO2 emission during composting.
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