Intermittent Aeration for In-vessel Composting Of Crab Processing Waste

A crab processing waste/wood shaving mixture was composted in-vessel with four intermittent aeration strategies. The composting process was monitored to assess the efficacy of the aeration methods. Temperature, moisture content and volatile solids of the compost were monitored along with the interstitial oxygen concentration. There was no significant difference in temperature profiles between constant frequency aeration and temperature feedback controlled aeration methods. An increased frequency of aeration resulted in significantly more drying than the less frequent aeration using the same total air volume. Results indicated that air volume could be reduced after the first five days of composting, and the in-vessel composting retention time could be reduced to 15 to 17 days for odor and vermin/vector problems prevention.     

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.     

In-vessel,Mechanical Rotating Drum Composting Of Institutional Food Residuals

Use of composting technology as a treatment/disposal method for food residuals has been investigated by numerous researchers. This project evaluated the applicability of in-vessel, mechanical, rotating drum composting for food residuals. Three batches of food residuals (plate scrapings) were collected from a Texas prison and mixed with fine-textured soft-wood shavings at 2/1, 3/1 and 4/1 (ratios of shavings to food residual on a volumetric basis) to produce 0.4 m³ of compost blend. Temperature, oxygen, pH, bulk density and porosity were tracked throughout a fifteen-day composting trial. Volume and weight reductions were noticed for all blends. All blends reached thermophilic temperatures (> 45°C) while remaining aerobic during the trials. Initial pH was low in all blends, occasionally reaching 3.55 before returning to optimal levels (6.0 to 7.5) for composting. Temperature increases into the thermophilic range during composting corresponded to increases in compost pH. Most nutrients (P, K, Ca, Mg, S, Na and Zn) increased in concentration during the composting period, with the exception of N, which in some instances decreased over time. Composts utilizing the 3/1 ratio of bulking agent/food residual achieved thermophilic temperatures quickest and maintained temperatures longer than did other blending ratios. From this study, it appears that use of the mechanical, in-vessel, rotating drum composter may be a viable alternative for food residual disposal.     

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 Food Processing Waste in the European Economic Community

For more than half a century, large food processing companies, faced with mounting solid waste disposal problems, have opted for landfilling. Other options, concentrating on utilization, are now being increasingly explored. Energy recovery (ethanol and methanol) and fodder production from food processing residuals in some cases are valid solutions. Of the many alternatives to food recovery waste disposal, composting seems to be an effective method. Managed properly, research has shown that composting can produce a nutrient-rich soil amendment; odors can be controlled during the transformation process and in the final product. The process is competitive and cost-effective environmentally, completes the biological chain and returns to the soil what has been taken from it. For these reasons, composting seems to be the best candidate to solve problems connected with food factory waste disposal.     

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.     

Windrow Cocomposting of Municipal Biosolids and Yard Waste

A total of four windrows with yard waste:biosolids ratios ranging from 5.0:1 to 1.2:1 by wet weight were operated over a six month period. The windrows were monitored for temperature, oxygen content, bulk density, particle size, compost characteristics (including metals, nutrients, pesticides, volatile solids, and moisture content), runoff characteristics, and odor potential. Based on study results, cocomposting should be employed at a yard waste:biosolids ratio greater than or equal to 3:1 in order to minimize odor and improve compost characteristics. Leaching of several metals was observed; however, only lead was observed in the runoff at concentrations above maximum contaminant levels.     

Inactivation of Giardia Cysts and Cryptosporidium Oocysts in Beef Feedlot Manure By Thermophilic Windrow Composting

Effects of composting manure on viability of Giardia cysts (GC) and Cryptosporidium cysts (CO) were determined in a two-year study with manure from feedlot cattle bedded on barley straw or woodchips. Each year, manure was deposited in 8 m × 2.5 m × 2 m windrows (one per bedding type) on a sheltered concrete pad. On day 0, porous bags containing 100 g of feces from confirmed Giardia- and Cryptosporidium-positive cattle (9 bags per retrieval day in Year 1; 3 per day in Year 2) were implanted in the windrows. Replicate bags were placed on the concrete pads as uncomposted controls. Windrow temperature and water content were measured and compost was turned mechanically twice each week. Fecal bags were retrieved and subsampled for enumerations of total and viable cysts and cysts after 1, 2, 3, 7, 10, 17, 24 and 31 days in 1998 and after 1, 2, 3, 7, 9, 16, 23, 30, 42, 56, 70 and 98 days in 1999. Windrow temperatures (TEMP) exceeded 55°C during the fourth week of composting, and remained above 50°C for 4 wk thereafter in 1999. Bedding material did not affect overall mean temperature in either year, but TEMP was higher with straw than with woodchip from day 10 to day 17 in 1998 (P < 0.05) and on day 16 and day 42 in 1999 (P < 0.10). In 1998, moisture content decreased from 62.2 to 43.2% during composting of woodchip manure and from 67.3 to 39.3% during composting of straw manure. In 1999, moisture content decreased from 61.0 to 31.8% for woodchip and from 64.5 to 28.6% for straw compost. Percentage of viable CO declined gradually over the 31 days in 1998. The following year revealed a rapid decline in viability of GC and CO once compost temperature exceeded 55°C and viabilities of GC and CO were reduced to zero after 42 days (straw compost) and after 56 days (woodchip compost). Exposure of CO and GC to temperatures > 55°C for a period of 15 days appears to be an effective method of inactivating Giardia cysts and Cryptosporidium cysts in feedlot manure.     

Evolution of Organic Matter Within Sixty Days of Composting of Lignocellulosic Food Industry Waste in Malaysia

Empty fruit bunches (EFB), coffee grounds (CG), and palm oil mill sludge (POMS) were composted in the laboratory for 60 days in order to study the composting process of lignocellulosic food industry wastes. In the first part of the experiment, EFB, CG, and POMS were composted alone (composting of single lignocellulosic material), and in the second part, EFB was composted with CG (1EFB:1CG ratio) and POMS (1EFB:1POMS ratio). The effects of different turning frequencies on the physical and chemical properties of composting were observed and its relation with the degradation process was highlighted. Results showed that oil and grease were first degraded, followed by recalcitrant compounds like alpha-cellulose, hemicellulose, and lignin. Cellulose and hemicellulose were degraded mainly during the 60 days of composting, and the progressive reduction of the cellulose/lignin ratio proved that the main evolution of these wastes took place. It was observed that 3, 6, and 9 days of turning frequency did not affect the physicochemical properties of the compost. Composting EFB alone failed to achieve the required quality of maturity compost within 60 days, while CG and POMS recorded low in biological activity. Better results were shown in composting of EFB mixed with coffee grounds and POMS, the C/N ratio dropped to less than 20 by the 8th week of the composting period. Composting of mixed lignocellulosic materials showed larger changes compared to composting of single lignocellulosic material, reaching a C/N ratio below 20 within 8 weeks.     

厨余垃圾堆肥对烤烟土壤酶活性和细菌群落结构的影响

以滇中植烟土壤为研究对象，设置不同厨余垃圾堆肥(基肥)施用量：不施肥对照(CK)、低施肥量8 t/hm² (FWL)、中施肥量16t/hm² (FWM)、高施肥量24t/hm² (FWH)，研究厨余垃圾堆肥施用后土壤酶活性和细菌群落结构的变化特征，为厨余垃圾堆肥农田推广使用提供依据。结果表明：与CK相比，FWH处理可显著提高土壤的p H、有机碳、全氮、全磷、碱解氮、有效磷、脲酶活性、酸性磷酸酶活性、荧光素二乙酸水解酶活性(↑0.39%～89.42%)、土壤细菌OUT数目(↑12.91%)、Chao指数(↑11.20%)、Ace指数(↑11.37%)。变形菌门(Proteobacteria)的相对丰度随施肥量的增加而增加，而酸杆菌门(Acidobacteria)则相反；细菌群落的膜运输和碳水化合物代谢功能均在施肥后显著增强。脲酶活性、酸性磷酸酶活性、p H、全氮、全磷、碱解氮、有效磷指标对土壤细菌的群落组成和多样性均有影响，其中碱解氮和脲酶活性是调控菌群最主要的因子。     

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.     

Using Geographical Information Systems to Evaluate Decentralized Management of Municipal Food Waste

The implementation of decentralized waste management plans is stymied by an inability to communicate the costs and benefits of these plans in the decision making arena. The use of Geographical Information Systems (GIS) is vital toward carrying out feasibility tests, life-cycle assessments, and in presenting the results thereof. A preliminary GIS-based analysis was done for a decentralized in-vessel composting scheme for Bangkapi Ward in Bangkok, Thailand. The use of GIS in the introduction of decentralized waste management is discussed in general.     

Using a Biocell to Measure Effect of Compressive Settlement on Free Air Space and Microbial Activity In Windrow Composting

This paper describes the first equipment developed to include compressive loads in a physical model of the composting environment. This new type of composting reactor was named a biological load cell, or biocell for short. Our hypothesis was that the exclusion of compressive settlement in existing physical models may lead to errors if the data is used to design full-scale windrow composting facilities. Municipal biosolids were mixed with three organic amendments (wood chips, straw, and leaves) to yield mixture moisture contents of 55%. Compressive settlement analyses were completed by subjecting the mixtures to loads of 0, 4.3, 8.6, and 12.9 kPa using biocells. The effect of compressive settlement on microbial activity was investigated using the biosolids:leaf mixture under loaded (12.9 kPa) and unloaded conditions. The settlement behavior of all three mixtures was found to fit established soil compaction equations and new equations were developed to represent the vertical free air space (FAS) and bulk density profiles in composting systems. The FAS profiles indicated that existing physical models do not simulate the FAS conditions within a composting matrix and significant differences in microbial activity were observed between loaded and unloaded biocells. The microbial activity differences were attributed to the reduced FAS within the loaded biocells, which, in consequence, lead to lower pore space oxygen concentrations. It proved difficult, however, to simulate the air flow regime within a windrow composting matrix. To further develop the biocells, there is a need to investigate the in-situ stress conditions and natural draft ventilation rates of full-scale windrow systems. While further work is required to perfect the biocells as a physical model of the windrow composting environment, it has demonstrated its potential use for FAS analysis and as a standard bulk density apparatus. Using biocells, it is recommended that FAS curves be developed for a wide range of feedstock recipes. The biocell apparatus could also be developed as a standard bulk density test apparatus. Other important conclusions drawn from the work include: leaves should not be used as a bulking agent; wood chips showed superior bulking properties and are recommended for use in very high (3.7 m) windrows; straw showed intermediate bulking properties and should not be used for high windrows without further investigation; for all materials, compaction occurred rapidly after each incremental load, suggesting that windrow turning will do little to alleviate a low FAS problem associated with an incorrect composting recipe.     

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.     

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.     

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%。     

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 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.     

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。     

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.