Economic Analysis of Composting Crab Processing Waste

A study of composting crab processing waste (CPW) was performed to identify a cost-effective alternative to landfilling. If CPW could be economically recycled into a useful value-added product, the waste would not have to go to landfills, and could be sold commercially to the landscaping and nursery industries. Economic models of three systems were constructed and analyses performed using a variety of investment and operating costs. To ensure robust model analysis, several factors of the cost components were varied. The equivalent-uniform-annual-costs were used to compare the alternatives, Ag-Bag, windrowing, and landfilling the waste. Profit analysis was also performed for each of the proposed systems. The average annual cost for the processes of Ag-Bag 1, Ag-Bag 2, and windrowing was $62,903, $73,796, and $53,533 respectively. While none of the methods analyzed were profitable, windrowing results in the smallest loss of $?0.066/kg ($?63.08/ton) for all economic models considered, followed by Ag-Bag 1 with an average loss of $?0.107/kg ($?100.18/ton) and Ag-Bag 2 with an average loss of $?0.117/kg ($?109.80/ton). Although having the least loss, windrowing has drawbacks such as offensive odors. A sensitivity analysis to determine how much additional throughput would have to be utilized to create a profit was performed. This analysis found that the windrow system is the only system capable of ever garnering a profit, with a total throughput exceeding 1,003 tons/year. Under current market conditions, composting CPW by one of the systems described herein is not feasible.     

Composting of Food Waste and Waste Paper with Top soils for Nitrogen Catching

Abstract

Food waste, waste paper and different topsoils were composted in different experiments. The composts were characterised by high contents of N, P, S, Na and K in the food waste, of Mg in the soil, and of Ca in paper and soils. The nitrogen catching was between 50 and 70% of the input. The lowest amounts were caught in the composts with sandy soils, the highest in a clay soil with high ignition loss.     

Composting of Fish Waste with Wood By-Products and Testing Compost Quality as a Soil Amendment: Experiences in the Patagonia Region of Argentina

Composting experiments of fish processing wastes and wood by-products were conducted in the Andean-Patagonian Region. Fish wastes were mixed with sawdust + wood shavings (3:1 ratio by weight) with two replicates. Materials were mixed and placed in 220-liter PVC reactors. After 20 days, materials were remixed and reloaded in the reactors. Samples were taken at 20, 30, 40, 60, 80 and 100 day intervals and chemical analyses were made to assess predictors of compost stability. Thermophilic temperatures over 55°C were sustained long enough to satisfy the EPA requirements for pathogen reduction (72 hours). The decrease of NH₄+-N, water soluble carbon and the ratio of water soluble carbon to total nitrogen appeared to be the best parameters for predicting compost stability. Mature compost (CMP) and an organic commercial product, Lombriquen (LQN) were incubated with an Andisol and a Xeric Mollisol at a rate of lOg/kg for 16 weeks (20 to 30 percent soil moisture, 25°C) in order to estimate nitrogen and phosphorus release. Soils amended with LQN retained more P than CMP-amended soils (80 percent vs 60 percent of added Olsen-P in the Andisol and 50 vs 35 percent in the Xeric Mollisol). While N mineralization rates of LQN were variable (three to 11 percent of added total N), CMP showed constant rates for both types of soils (12 percent) and released more available N than LQN.     

温度和物料配比对城市园林绿化废物与鸡粪水浴法好氧堆肥的影响

[目的]探究温度和物料配比对城市园林绿化废物与鸡粪水浴法好氧堆肥的影响,为大规模好氧堆肥提供技术指导与理论基础。[方法]以恒温水浴锅、空气泵、气体转子流量计、温度计、发酵瓶与洗气瓶为材料,构建水浴法温控好氧堆肥装置,开展城市园林绿化废物与鸡粪质量比分别为2∶3,2∶1,3∶1,5∶1(分别命名A,B,C,D组)水浴法堆肥试验。[结果]城市园林绿化废物与鸡粪发酵堆肥微生物代谢活性最佳温度在50～55℃之间,当温度≥55℃,微生物对有机物的降解受到明显抑制。从温度变化看,A—D组堆肥均经历了升温期、高温期、降温期和中温期。A—D组堆肥氮素损失率分别为47.11%±0.55%,63.82%±1.05%,53.43%±0.71%和36.38%±0.83%,D组堆肥的保氮量最高。从种子发芽率与发芽指数看,A—D组堆肥产物发芽率分别为96.7%±2.11%,96.7%±2.25%,84.4%±1.98%和96.7%±2.06%,堆肥产物均达到腐熟度评价标准(≥80%)。[结论]城市园林绿化废物与鸡粪水浴法好氧堆肥最佳温度为50～55℃,D组堆肥的保氮量最高,4组堆肥产物均达到腐熟度评价标准。     

Assessment of Fulvic Acid-Like Fractions during Tannery Waste Composting

Changes in the structural composition of fulvic acids were followed during composting of tannery solid waste after neutralization of its acidity by ammonium or by lime. Different techniques (elemental analysis, Fourier transform infrared (FTIR), ¹³C-NMR spectroscopy) were applied. During both trials of composting, a decrease of carbon and increase of oxygen occurred, which originated from strong microbial oxidation and preservation of some structures during composting. In fact, Nuclear Magnetic Resonance (NMR) spectra showed the preservation of anomeric or tannin structures around 105 ppm. The infrared (IR) spectral data showed a decrease in the intensity of COO^? group bands (1623 and 1399.5 cm^?1); this is correlated with a decrease of fulvic acid levels. The variations observed in NMR spectra could be explained by the involvement of COO^? groups of certain structures in polycondensing to form humic acids. The fulvic acids remain composed of less polycondensed structures with a –COOH extremity, as supported by a decrease of the C/H ratio. In contrast, in the trial with addition of ammonia a slight increase in N content occurred, a decrease in absorbance in the 1730–1000 cm^?1 regions compared to the absorbance around 3400 cm^?1, and a strong decrease of carboxyl carbon in the ¹³C-NMR spectra.     

A Kinetic Model of the Yard Waste Composting Process

A new kinetic concept was applied to the yard waste composting process. Yard waste mixtures with different fractions of grass clippings were composted in pilot-scale vessels. Ammonia emissions were highest with high fractions of grass clippings. Calculation of reaction rate constants was based on heat and materials balances. Although the compost mass ratios (a dimensionless number that describes how far the process has advanced) of the mixtures after composting were similar, their chemical and biological analyses reveal differences. A first order reaction model is presented that can be used for plant design. The effects of temperature and particle size on process kinetics need to be investigated further.     

厨余垃圾沼渣堆肥与化学改良剂对城市搬迁地土壤团聚体形成的影响

为改善城市土壤团粒结构，以上海典型搬迁地土壤为研究对象，通过室外培养试验，研究了不同用量厨余垃圾沼渣堆肥和化学改良剂分别单施以及混施对土壤水稳定性团聚体、团粒结构形成的影响。结果表明：20%、30%沼渣堆肥单施处理可显著增加搬迁地土壤0.5~1.0、1.0~2.0 mm粒径大团聚体以及0.106~0.25 mm粒径微团聚体质量分数（P<0.05），而显著降低<0.106 mm粒径微团聚体质量分数（P<0.05）。化学改良剂β-环糊精单施处理可显著增加土壤微团聚体总量（P<0.05）；3 kg/m³用量硫酸钙、氧化铁单施处理均可显著促进土壤大团聚体的形成（P<0.05）。沼渣堆肥和化学改良剂混施处理较单施处理显著增加土壤>2.0、0.25~0.5 mm粒径大团聚体质量分数（P<0.05），而降低<0.106 mm粒径微团聚体质量分数（P<0.05）。在沼渣堆肥处理中，以20%沼渣堆肥添加量对土壤团粒结构改良效果最佳；在化学改良剂处理中，以3 kg/m³硫酸钙处理对土壤团粒结构改良效果最佳，其次是3 kg/m³氧化铁处理。WG₂₀+SM_mix处理（20%沼渣堆肥+化学改良剂混施）对搬迁地土壤团粒结构改良效果最佳，团粒结构达19.03%，较CK（对照组）、SM_mix（化学改良剂混施）、WG₂₀（20%沼渣堆肥）处理分别提高了94.0%、73.5%和26.0%。     

Composting of Yard Waste and Wastewater Treatment Plant Sludge Mixtures

Composting of yard waste and sludge/yard waste mixtures was investigated during laboratory and field testing. A strong correlation between moisture content and windrow peak temperatures was observed. Odors were detected at cocomposting windrows when temperatures exceeded 54°C. The sludge to yard waste mixture ratio was found to affect resulting compost particle size and, consequently, oxygen transport. Compost quality was excellent, with pesticides below detection level and low concentrations of heavy metals.     

Windrow Composting of Waste Paint Sludge Containing Melamine Resins

ABSTRACT

Melamine resins (MR), widely used in various industries, are thermosetting plastics that have hard and durable properties. These resins can be introduced into the environment as components of waste products or via industrial effluents. It is important to seek environmentally friendly means to recycle, remove, or degrade melamine resins before they are released to the environment. Waste paint sludge containing MR has been shown to be efficiently composted under bench-scale conditions. In this study, the impacts of C/N ratios on windrow composting of waste paint sludge containing MR were evaluated. As composting proceeded, temperature, concentrations of MR and melamine degradation products (i.e., ammeline, ammelide, and cyanuric acid) were determined. After 98 days of composting, 87.5, 83.3, 80.9, and 70.1% of the initial MR were degraded under the treatments with C/N ratios of 30, 33, 35, and 37, respectively. Degradation of MR was enhanced by relatively low C/N ratios. Significant amounts of plant nutrients were found in the final composts, while heavy metals were well below values considered to be of concern regarding surface water quality or crop production. We conclude that adjusting C/N ratio to approximately 30 in the initial mixtures with oat and hay straws can increase the degradation of MR and its derivatives during windrow composting of waste paint sludge containing MR and produce a good quality compost product.     

园林废弃物堆肥红外光谱特性分析

以添加不同外源物质的园林废弃物为研究对象,采用近红外光谱分析方法跟踪测定不同堆肥阶段园林废弃物堆体中近红外光谱变化,结合堆体温度变化,探讨外源添加剂对堆肥物质结构转化影响。结果表明:单独添加腐殖酸处理(FZS)、复合添加EM菌剂和腐殖酸处理(EM+FZS)、复合添加京圃园菌剂和腐殖酸处理(JPY+FZS)以及无添加处理(CK)堆体物质转化机制相同,即随着堆肥进行,蛋白质,碳水化合物,脂肪类物质不断减少,物质芳构化程度提高,外源添加剂不影响堆肥物质转化顺序。不同外源添加剂处理红外光谱特征峰吸收频率位置基本一致,但特征峰吸收强度有所变化,说明不同外源添加剂堆肥物质中含有相似的官能团,但官能团数量与物质结构不同,外源添加剂对堆肥分解速率,分解程度以及堆肥产物芳化度均有影响。京圃园菌剂与腐殖酸复合施用(JPY+FZS)能够显著加速物质转化进程,提高堆肥产品芳化程度,更适宜应用于园林废弃物堆肥。     

Composting Olive Mill Waste and Sheep Manure For Orchard Use

An industrial-scale composting plant has been designed for producing organic fertilizers from olive mill waste using the windrow pile system. Materials to be composted, two phase olive mill waste (TPOMW) and sheep litter (SL), were characterized and made into three piles consisting of different proportions of each. Throughout the composting process, temperature (T), moisture (M), organic matter (OM), total organic carbon (C_org), total nitrogen (NT), germination index (GI), pH and electrical conductivity (EC) were monitored. The potential agronomic value of the final composts was ascertained by analyzing the bulk density, OM and Corg concentration, pH, EC, macro and micronutrient content (N, P, K, Ca, Mg, Fe, Cu, Mn, Zn, B), the concentration of humic and fulvic acids and inorganic nitrogen (NH₄⁺,NO₂^?,NO₃^?). Each compost was applied to an area of one hectare within a six year-old olive plantation. Four months after application, the soils showed an increased OM concentration and cationic exchange capacity (CEC).     

废弃烤烟茎秆与鸡粪堆肥化利用的研究

采用特制的堆肥箱,对废弃烤烟茎秆与鸡粪的堆肥化利用进行了研究。结果表明,烤烟茎秆＋鸡粪（处理A）混合堆肥处理的堆温保持在50℃以上的时间为10d,而烤烟茎秆＋碳酸氢铵（处理B）处理的仅为2d。堆肥30d时,处理A的碳素含量基本趋于稳定,C／N为15．8;处理B的碳素含量仍不稳定,C／N为23．5;处理A的铵态氮与硝态氮的比值为0．43,处理B的达0．60。堆肥20d时,处理A堆料浸出液浸种后的种子发芽指数比处理B的高15个百分点,差异达极显著水平。堆肥50d时,两处理的种子发芽指数差异不明显,种子发芽率均达到100％。烤烟茎秆与鸡粪堆肥成品的有机质和总养分（N、P2O5、K2O）含量、重金属（As,Hg,Ph,Cd,Cr）含量控制标准等完全达到有机肥质量的要求。     

Design and Performance of a Simulated Feedstock for Composting Experiments

This paper reviews the composition and performance of simulated feedstock mixtures previously employed in composting research, and presents a new simulated feedstock. The new feedstock was prepared using readily available dry ingredients — ostrich feed pellets, office paper, finished compost and woodchips — representing the substrate, amendment, seed, and bulking agent components of a composting mixture respectively. The design criteria chosen were a) a substrate plus amendment C:N ratio of 30:1, b) an energy ratio of > 800 cal/g-H₂O, c) a water ratio of < 8 g-H₂O/g-BVS, d) a wet bulk density of < 600 kg/m³ and e) a moisture content of 60% (w/w). Resultant final proportions of the substrate:amendment:seed:bulking-agent:added-water mix were 0.071:0.098:0.009:0.267:0.555 (w/w). When composted in a controlled temperature difference (CTD), forced-aeration reactor operated with condensate return, the mixture was shown to self-heat rapidly and remain at realistic temperatures for extended periods. Thermophilic temperatures were reached within 22-33 h of start-up, following lag periods of 13-22 h, and maintained for up to 34 d. Final compost characteristics were consistent with a normal composting process. It is suggested that future variations in the simulated feedstock composition could be made, and proposed that use of this type of feedstock would facilitate future experimental work associated with composting kinetics and temperature profile modeling.     

垃圾好氧堆肥渗滤液与填埋场渗滤液的比较

通过以配制的城市垃圾和实验室堆肥装置,通过12d的堆肥,研究好氧堆肥渗滤液的成分,将其与新填埋渗滤液、成熟填埋渗滤液以及世界卫生组织标准（1984年）进行详细的比较。结果表明：堆肥渗滤液呈碱性,大于新填埋场和成熟填埋场渗滤液的pH;COD、NH4^＋ -N和BOD5等参数对比说明了一次堆肥过程较新填埋场发酵过程成熟,但没有成熟填埋场发酵更彻底;堆肥渗滤液是一种有机营养的废水,同时富含大量的微生物。     

Impact of Composting Food Waste with Green Waste on Greenhouse Gas Emissions from Compost Windrows

Windrow composting of green waste as an alternative to green waste disposal in landfills requires an understanding of the impacts on greenhouse gas (GHG) emissions and the development of effective and efficient management strategies to reduce these emissions. The addition of food waste to green waste compost operations is becoming more common, but its effect on GHG emissions is less understood. As more food waste diversion occurs as a result of recent implementation of climate smart policies in California, more information is needed to address the sustainability of composting different combinations of waste types. We monitored GHG emissions from compost windrows comprised of green waste alone and a green/food waste mixture (green waste : food waste = 9:1, by wet weight) at the University of California, Davis Student Farm in 2016 using a modified, open, flow-through chamber technique. When comparing total emissions of nitrous oxide (N₂O) and methane (CH₄), the green/food waste mixture produced 110?kg CO₂ eq./ton DM (dry matter, std error = 12.2), which were slightly lower than emissions produced by the green waste alone (152?kg CO₂ eq./ton DM, std error = 15.9). Methane was a large contributor to global warming potential (GWP) of both composting treatments, suggesting that management practices that optimize porosity and air flow in compost piles are promising in reducing emissions from both green waste and green/food waste mixtures.     

竹炭添加对厨余垃圾好氧堆肥过程的影响

为了探讨竹炭对厨余垃圾好氧堆肥过程的影响,向厨余垃圾添加稻草调节堆肥原料初始含水率为70%后,分别添加0%和5%的竹炭(竹炭与堆肥原料湿基比)进行为期15 d的好氧堆肥,研究了堆肥过程中堆体温度、厨余垃圾和稻草有机物降解率及堆肥腐熟程度的变化。结果表明:竹炭的添加增加了厨余垃圾好氧堆肥高温(> 55℃)持续时间,且高温阶段的前4天,添加5%竹炭堆体温度都明显高于对照;竹炭的添加提高了堆肥过程中有机物的降解率,堆肥结束时,与添加5%竹炭堆体其厨余垃圾和稻草的有机物降解率分别比对照提高了20.6%和29.2%,表征腐熟化程度的SUVA254和SUVA280值分别提高了15.6%和12.4%。以上结果表明,竹炭的添加促进了厨余垃圾堆肥过程有机物的降解,提高了堆肥产品的腐熟程度。     

Evolution of Biochemical Parameters During Composting of Urban Wastes

An experiment was performed for evaluating the most suitable biochemical parameters to measure dynamics of substrate transformation during composting of the organic fraction derived from preselected urban wastes and wood bark mixture. Changes of chemical (organic C, hydrosoluble sugars, total and mineral N, humified fraction, volatile acids and phenolic compounds) and biochemical (microbial respiration, biomass C, qCO₂, dehydrogenase, catalase, urease activities, FDA, and BIF) parameters were monitored for 120 days. Limited changes in organic C, total nitrogen, and humification characteristics were observed during composting. Dehydrogenase and catalase activities, BIF and FDA showed small changes during composting. Urease activity and, with some limitations regarding the early stages of composting, microbial respiration and qCO₂, were found to be the most suitable parameters to measure dynamics of substrate transformation during composting of preselected urban wastes.     

Optimization of Medlar Pruning Waste Composting Process by Cattle Manure Addition

In this study, medlar pruning waste (MPW) was composted with and without cattle manure (CM). Two piles were prepared: one contained only MPW (pile 1) and one contained MPW augmented with CM (pile 2). Both piles were composted in an enclosed composting vessel with passive aeration and aeration by turning. During the composting process, temperature, pH, electrical conductivity (EC), organic matter (OM), OM losses, total organic carbon (C_org), total nitrogen (N_T), C_org/N_T ratio, and germination index (GI) were measured. Pile 2 produced a faster increase of the temperature and had a longer thermophilic phase than pile 1. However, the rate of OM degradation was faster in pile 1 than in the pile containing CM (pile 2). The addition of CM also resulted in an increased pH and salt content. In both piles, C/N ratio decreased throughout the process, presumably as a result of the faster organic carbon degradation compared to N mineralization. However, only pile 2 had a final C/N ratio <20, the limit accepted for compost by the Spanish legislation on fertilizer. Also, both composts had GI > 50 percent, indicating an absence of phytotoxicity.     

Yard Waste Composting: Studies Using Different Mixes of Leaves and Grass in a Laboratory Scale System

Composting has become a widely used method of recycling yard wastes such as leaves and grass. However, very little information is available on the chemical changes that occur during the composting of different mixtures of leaves and grass. In this study, three different mixes of leaves and grass were composted at approximately 60% moisture in a temperature controlled laboratory scale system. The mixes, which consisted of all leaves (Mix 1); 2/3 leaves + 1/3 grass (Mix 2); and 1/3 leaves + 2/3 grass (Mix 3), had initial C:N ratios of 48, 30 and 22, respectively. The compost process was monitored by measuring the rate of CO₂ evolution, pH, stability, the degree of humification and changes in polysaccharide, carbon, nitrogen and organic matter content. Results showed that the greater the grass content of the mix, the higher the initial pH and the faster the rate of CO₂ evolution, organic matter loss and nitrogen loss. After 43 days of composting, Mixes 1, 2 and 3, lost, respectively 61%, 74% and 78% of the cellulose, 57%, 79% and 82% of the hemicellulose and 40%, 49% and 42% of the acid-insoluble organic matter. Humification indices and stability tests indicated that composts produced from the three mixes were well humified and stable.