Two-stage Composting Of Green Waste Research Articles

Food waste and montmorillonite contribute to the enhancement of green waste composting

Composting is currently the best strategy to dispose of green waste (GW) containing substantial quantities of lignocelluloses that prolongs composting time and yields unstable compost. This study aimed to evaluate the effects of food waste (FW, at 0%, 35%, and 55%) and montmorillonite (M, at 0%, 10.5%, and 15.5%) as the composting amendments on the physicochemical and microbial characteristics of compost in two-stage composting of GW. Changes in temperature, bulk density, C/N ratio, carbon dioxide emission, organic matter, humic substances, lignocellulosic substances, microbial numbers, and phytotoxicity were assessed during GW composting. The results demonstrated that combining FW and M exhibited positive effects, and 35% FW and 15.5% M obtained the best results in all compost characteristics. The optimum extended thermophilic period, enhanced lignocellulose decomposition, and generated a stable and mature product in only 21 days. Consequently, the best final compost was mature (C/N ratio: 7.01, HAs/FAs ratio: 3.14, and NH4+-N/NO3–-N ratio: 0.10), nutrient-rich (N: 4.89%, P: 2.01%, and K: 0.92%), and no phytotoxic (germination index: 145%). This study unveils the effects of FW, M, or a combination of FW and M on compost characteristics. The study therefore increases the understanding of the sustainable disposal of an important solid waste.

Improvement of two-stage composting of green waste by addition of eggshell waste and rice husks

With the development of urban greening and increases in the human population, the production of green waste (GW) has been increasing in China. Although GW is biodegradable, its composting is difficult because of its low degradation rate. This study focuses on how addition of eggshell waste (ESW; at 0, 10, and 20%) and/or rice husks (RH; at 0, 15, and 25%) affects the two-stage composting of GW on the basis of temperature, bulk density, particle-size distribution, pH, nitrogen changes, carbon dioxide emission, organic matter degradation, humic substances, the activities of microorganisms and enzymes, and the phytotoxicity to germinating seeds. The combined addition of 10% ESW and 25% RH produced the highest quality compost in the shortest time. To produce a stable and mature product, two-stage composting of GW required 30 days without additives but only 20 days with the combined addition of 10% ESW and 25% RH.

The use of coal fly ash and vinegar residue as additives in the two-stage composting of green waste.

Composting is an attractive way to recycle organic wastes because the product (compost) can be used as an organic fertilizer or a culture substrate. This study assessed coal fly ash (CFA; at 0, 15, and 35%) and/or vinegar residue (VR; at 0, 35, and 55%) as additives in the green waste (GW) composting process. Compost maturity was assessed based on the following indicators: water-holding capacity, pH, total organic carbon, electrical conductivity, total Kjeldahl nitrogen, and germination index. Other important compost properties that were determined included germination percentage and root length of seeds in a germination assay, crude fiber degradation, specific UV absorption, E4/E6 ratio, microbial numbers (culturable bacteria and volatile fatty acid-degrading bacteria), enzyme activities (dehydrogenase, β-glucosidase, acid-phosphatase, urease, and ortho-diphenol oxidase), and available nutrients. When added together, CFA and VR improved all of these properties. As indicated by the maturity indicators and other properties, the best treatment (the combined addition of 15% CFA and 55% VR) required only 23 days to produce a mature and high quality compost.

Changes in Physical, Chemical, and Microbiological Properties During the Two-Stage Composting of Green Waste due to the Addition of β-cyclodextrin

This research determined whether addition of β-cyclodextrin (β-CD; 0, 0.15, or 0.25%) improved the two-stage composting of green waste (GW). The following parameters were measured during composting or in the final product: moisture content; volume; biochemical and chemical oxygen demand; humic substances; C/Nsolid and C/Nsoluble; microbial numbers (culturable bacteria, actinomycetes, and fungi); enzyme activities (pectinase and xylanase); microbial biomass carbon and nitrogen; degradation of organic components; contents of phosphorus (available and total), potassium, sodium, calcium, and magnesium; and toxicity to germinating seeds. The two-stage composting of GW was optimal with the addition of 0.15% β-CD. A mature and stable compost was obtained in only 28 days with the optimized two-stage composting rather than in the 90–270 days typically required for traditional composting.

Effects of waste lime and Chinese medicinal herbal residue amendments on physical, chemical, and microbial properties during green waste composting.

Traditional composting is time-consuming and often results in a low-quality product. The objective of this study was to determine the effects of waste lime (WL; at 0, 2.5, and 3.5%) and/or Chinese medicinal herbal residues (CMHRs; at 0, 10, and 20%) as amendments on the two-stage composting of green waste (GW). The combination of WL and CMHRs improved compost particle-size distribution and pH, decreased nitrogen loss, and increased cation exchange capacity (CEC), nutrient content, and microbial numbers. The combination of WL and CMHRs also accelerated organic matter humification and lignocellulose degradation and therefore increased the germination index of the final compost. Relative to the non-amended compost, the optimal amendment (2.5% WL and 20% CMHRs) increased the percentage of particles of ideal size from 23.8 to 66.9%, the pH from 6.69 to 7.17, the CEC from 52 to 169cmol/kg, the humic acid to fulvic acid ratio from 1.32 to 2.49, the hemicellulose degradation rate from 42 to 87%, and the cellulose degradation rate from 20 to 61%. The treatment with addition of 2.5% WL and 20% CMHRs to GW required only 21days to generate the highest quality compost product.

Influence of sugar beet pulp and paper waste as bulking agents on physical, chemical, and microbial properties during green waste composting

Composting is considered to be a natural, sustainable, and highly beneficial method for solid waste disposal. The objective of this study was to investigate the two-stage composting of green waste (GW) as affected by the addition of sugar beet pulp (SBP; at 0, 25, and 35%) and/or paper waste (PW; at 0, 5, and 10%) as bulking agents. The combination of SBP and PW greatly improved the composting conditions and the final compost quality in terms of composting temperature; pH; emissions of ammonia, nitrite nitrogen, and carbon dioxide; lignocellulose degradation; microbial abundance; enzyme activities; particle-size distribution; the ratio of water-soluble organic carbon to organic nitrogen; and phytotoxicity. The optimal two-stage composting process of GW and the highest quality compost product were obtained with the combination of 25% SBP and 10% PW. This optimal combination of bulking agents produced a mature and stable final compost product in only 20 days.

Evaluation of maifanite and silage as amendments for green waste composting

Composting is a popular method for recycling organic solid wastes including agricultural and forestry residues. However, traditional composting method is time consuming, generates foul smells, and produces an immature product. The effects of maifanite (MF; at 0%, 8.5%, and 13.5%) and/or silage (SG; at 0%, 25%, and 45%) as amendments on an innovative, two-stage method for composting green waste (GW) were investigated. The combined addition of MF and SG greatly improved composting conditions, reduced composting time, and enhanced compost quality in terms of composting temperature, bulk density, water-holding capacity, void ratio, pH, cation exchange capacity, ammonia nitrogen content, dissolved organic carbon content, crude fibre degradation, microbial numbers, enzyme activities, nutrient contents, and phytotoxicity. The two-stage composting of GW with 8.5% MF and 45% SG generated the highest quality and the most mature compost product and did so in only 21 days. With the optimized composting, the degradation rate of cellulose and hemicellulose reached 46.3 and 82.3%, respectively, and the germination index of Chinese cabbage and lucerne was 153 and 172%, respectively, which were all far higher than values obtained with the control. The combined effects of MF and SG on GW composting have not been previously explored, and this study therefore provided new and practical information. The comprehensive analyses of compost properties during and at the end of the process provided insight into underlying mechanisms. The optimized two-stage composting method may be a viable and sustainable alternative for GW management in that it converts the waste into a useful product.

Effects of bean dregs and crab shell powder additives on the composting of green waste

Composting is an effective and economic technology for the recycling of organic waste. In this study, bean dregs (BD) (at 0, 35, and 45%) and crab shell powder (CSP) (at 0, 15, and 25%) were evaluated as additives during the two-stage composting of green waste (GW). The GW used in this experiment mainly consisted of branch cuttings collected during the maintenance of the urban green landscape. Combined additions of BD and CSP improved composting conditions and compost quality in terms of composting temperature, specific surface area, average pore diameter, pH and EC values, carbon dioxide release, ammonia and nitrous oxide emissions, E4/E6 ratio, elemental composition and atomic ratios, organic matter degradation, microbial numbers, enzyme activities, compost phytotoxicity, and environmental and economic benefits. The combined addition of 35% BD and 25% CSP to the two-stage composting of GW resulted in the highest quality compost product in only 22 days.

Addition of seaweed and bentonite accelerates the two-stage composting of green waste

Green waste (GW) is an important recyclable resource, and composting is an effective technology for the recycling of organic solid waste, including GW. This study investigated the changes in physical and chemical characteristics during the two-stage composting of GW with or without addition of seaweed (SW, Ulva ohnoi) (at 0, 35, and 55%) and bentonite (BT) (at 0.0, 2.5%, and 4.5%). During the bio-oxidative phase, the combined addition of SW and BT improved the physicochemical conditions, increased the respiration rate and enzyme activities, and decreased ammonia and nitrous oxide emissions. The combination of SW and BT also enhanced the quality of the final compost in terms of water-holding capacity, porosity, particle-size distribution, water soluble organic carbon/organic nitrogen ratio, humification, nutrient content, and phytotoxicity. The best quality compost, which matured in only 21days, was obtained with 35% SW and 4.5% BT.

Addition of fish pond sediment and rock phosphate enhances the composting of green waste

The objective of this work was to study the two-stage composting of green waste (GW) as affected by addition of fish pond sediment (FPS; at 0, 25, and 35%) and/or rock phosphate (RP; at 0, 10, and 15%). The combined addition of FPS and RP greatly accelerated GW degradation and improved compost quality in terms of composting temperature, windrow volume, pH, electrical conductivity (EC), cation exchange capacity (CEC), NH3 emission, microbial biomass, enzyme activities, nutrient content, and seed germination. The two-stage composting was optimal with the combined addition of 25% FPS and 15% RP. In addition to producing the highest quality compost product, the optimal combination resulted a mature compost in only 22days rather than in the 90–270days required with traditional composting.

Improving green waste composting by addition of sugarcane bagasse and exhausted grape marc

The composting of lignocellulosic waste into compost is a potential way of sustainably disposing of a waste while generating a useful product. The current study determined whether the addition of sugarcane bagasse (SCB) (at 0, 15, and 25%) and/or exhausted grape marc (EGM) (at 0, 10, and 20%) improved the two-stage composting of green waste (GW). The combined addition of SCB and EGM improved composting conditions and the quality of the compost product in terms of temperature, water-holding capacity, particle-size distribution, coarseness index, pH, electrical conductivity, water-extractable organic carbon and nitrogen, microbial numbers, enzymatic activities, polysaccharide and lignin content, nutrient content, respiration, and phytotoxicity. The optimal two-stage composting and the best quality compost were obtained with the combined addition of 15% SCB and 20% EGM. With the optimized two-stage composting method, the compost matured in only 21days rather than in the 90–270days required for traditional composting.

Influence of bulking agents on physical, chemical, and microbiological properties during the two-stage composting of green waste

A recyclable organic bulking agent (BA) that can be screened and was developed to optimize green waste (GW) composting. This study investigated the use of wood chips (WC) (at 0%, 15%, and 25%) and/or composted green waste (CGW) (at 0%, 25%, and 35%) as the BAs in the two-stage composting of GW. The combined addition of WC and CGW improved the conditions of composting process and the quality of compost product in terms of composting temperature, porosity, water retention, particle-size distribution, pH, electrical conductivity (EC), cation exchange capacity (CEC), nitrogen losses, humification indices, microbial numbers, enzyme activities, macro- and micro-nutrient contents, and toxicity to germinating seeds. The compost matured in only 22days with the optimized two-stage composting method rather than in the 90–270days typically required for traditional composting. The optimal two-stage composting process and the best quality of compost product were obtained with the combined addition of 15% WC and 35% CGW.

Effects of earthworm casts and zeolite on the two-stage composting of green waste

Because it helps protect the environment and encourages economic development, composting has become a viable method for organic waste disposal. The objective of this study was to investigate the effects of earthworm casts (EWCs) (at 0.0%, 0.30%, and 0.60%) and zeolite (clinoptilolite, CL) (at 0%, 15%, and 25%) on the two-stage composting of green waste. The combination of EWCs and CL improved the conditions of the composting process and the quality of the compost products in terms of the thermophilic phase, humification, nitrification, microbial numbers and enzyme activities, the degradation of cellulose and hemicellulose, and physico-chemical characteristics and nutrient contents of final composts. The compost matured in only 21days with the optimized two-stage composting method rather than in the 90–270days required for traditional composting. The optimal two-stage composting and the best quality compost were obtained with 0.30% EWCs and 25% CL.

Effects of rhamnolipid and initial compost particle size on the two-stage composting of green waste.

Composting is a potential alternative to green waste incineration or deposition in landfills. The effects of the biosurfactant rhamnolipid (RL) (at 0.0%, 0.15%, and 0.30%) and initial compost particle size (IPS) (10, 15, and 25 mm) on a new, two-stage method for composting green waste was investigated. A combination of RL addition and IPS adjustment improved the quality of the finished compost in terms of its physical characteristics, pH, C/N ratio, nutrient content, cellulose and hemicellulose contents, water-soluble carbon (WSC) content, xylanase and CMCase activities, numbers of culturable microorganisms (bacteria, actinomycetes, and fungi), and toxicity to germinating seeds. The production of a stable and mature compost required only 24 days with the optimized two-stage composting method described here rather than the 90-270 days required with traditional composting. The best quality compost was obtained with 0.15% RL and an IPS of 15 mm.