Microbial Population Dynamics and Enzyme Activities During Composting

The changes in population size of different microbial groups (total aerobic heterotrophs, actinomycetes, fungi, fecal coliforms, ammonium- and nitrite-oxidizing bacteria, and denitrifying bacteria) and the activities of 19 different enzymes (three phosphatases, three esterases, two proteases, three amino-peptidases, and eight glycosyl-hydrolases) were examined during cocomposting of poultry litter (a mixture of poultry manure, waste feed, feathers, and wood shavings) and yard trimmings (a mixture of grass clippings, leaves, and wood barks). Three piles with forced aeration were established by mixing 2:1 (v/v) ratio of poultry litter and yard trimmings. During composting, samples were taken at three different locations (top, middle, and bottom) of the forced aeration piles for microbial and enzyme analyses. Results demonstrated that population size of different microbial groups was not a limiting factor in this composting process as the microorganisms in the poultry litter + yard trimmings compost are in great abundance. Although the numbers of these microbial groups were reduced by high temperature, their populations multiplied rapidly as composting progressed. Fecal coliforms were eliminated by day 49, suggesting that the poultry litter + yard trimmings compost showed an overall increase in diversity and relative abundance of extracellular enzymes present as composting progressed. The population of fungi and actinomycetes (microorganisms active in degradation of cellulose, hemicellulose, and lignin) were positively correlated with esterase, valine amino-peptidase, α-galactosidase, β-glucosidase, and lipase. Of all 19 enzymes examined, ß-galactosidase (enzyme involved in the hydrolysis of lactose) had the most significant positive correlation with microbial populations, such as total aerobic heterotrophs, ammonium- and nitrite-oxidizing bacteria, denitrifying bacteria, and fecal coliforms. Cystine amino peptidase, chymotrypsin, and trypsin showed no evidence of activity during the entire period of composting. This composting process represented a combined activity of a wide succession of environments in the compost pile as one microbial group/enzyme overlapped the other and each emerged gradually as a result of the continual change in temperature as well as moisture content, O₂ and CO₂ level, and progressive breakdown of complex compounds to simpler ones.     

Changes of Chemical Forms of Zinc and Zinc Sulfide During the Composting Process of Municipal Solid Waste

Changes of chemical forms of metallic zinc and zinc sulfide during the composting process of municipal solid waste in oxygen conditions have been determined. Speciation of zinc was carried out by means of sequential extraction. It has been found that contamination of the waste with Zn is dangerous to the environment because zinc accumulates in bioavailable forms - organically bound and carbonate. Zinc sulfide remains mainly in a less mobile sulfide form. The composting process increases the mobility of zinc insignificantly.     

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。     

Enzyme Activities as Indicators of Municipal Solid Waste Compost Maturity

Composts of municipal solid waste in a commercial scale facility were assayed for enzymatic activities over time. The main enzymes assayed in this study were alkaline phosphatase, acid phosphatase, endo-cellulase, glucosidase, and lipase (C10). The biomass was measured by using lipid phosphate as a measure of the amount of cellular membranes, and metabolism was measured by the amount of 14_C-acetate incorporated into the lipid phosphate pool. All tests followed steady trends which show promise for use as possible stability and maturity indicators. Cellulase activity appears to be a good indicator of stability. The lipase activity appears to be a good indicator of compost maturity. A simple test strip (Api-Zyme from Api Analytab Products, Plainview, New York) was also used and compared to the standard enzyme assay methods. Api-Zyme and standard methods gave comparable results. The use of specific enzymatic activities presents an inexpensive and fast method, which may be combined with others, to predict a composts' stability and possible maturity status based on microbial activity.     

Application of Experimental Design Technique to the Optimization of Bench-Scale Composting Conditions of Municipal Raw Sludge

Evaluation of the parameters affecting the compostability of dewatered raw sludge from a wastewater treatment plant has been carried out by means of a full factorial composite experimental design. The factors and their correspondent levels considered in the experimental design were: bulking agent:sludge ratio (from 1:1 to 4:1 by volume), bulking agent particle size (from 0-5 mm to 10-20 mm) and composting volume (in the range of typical laboratory-scale, from 1.5 to 25 L). Experimental design has permitted obtaining a polynomial second-order function that quantitatively describes the influence of the considered factors on the compostability of this waste in laboratory reactors. The function has been numerically optimized to find the optimal values for composting raw sludge resulting in a values of: 0-5 mm for bulking agent size, 1:1 for ratio bulking agent:sludge and a composting volume around 10 L. The use of this technique can be generalized and applied to the composting of other organic wastes and will permit comparison of composting performance of different wastes.     

倒仓破碎对缩短发酵周期后生活垃圾堆肥腐熟度的影响

为了满足日益增长的垃圾处理发展的需要,解决城市生活垃圾产生与消纳、处理之间的矛盾,以北京市南宫堆肥厂垃圾堆肥工艺和密闭隧道发酵仓为研究对象,以马家楼转运站筛分出的15-80mm粒径垃圾作为堆肥原料,以14d高温隧道发酵（不倒仓不破碎）→21d后熟化发酵→21d最终熟化发酵工艺为对照,以8d高温隧道发酵（不倒仓不破碎）→12d后熟化发酵→12d最终熟化发酵工艺为处理1,8d高温隧道发酵（第3d倒仓破碎1次）→12d后熟化发酵→12d最终熟化发酵工艺为处理2。通过不同发酵阶段采样和各类指标的测定,探求缩短堆肥发酵周期后倒仓破碎工艺对于生活垃圾堆肥腐熟度的影响。结果表明,处理1产品的腐熟度较差,处理2与对照处理的堆肥产品腐熟度差异不明显。将高温隧道发酵时间由14d缩短为8d,并且第3d倒仓破碎1次,后熟化与最终熟化时间分别由21d缩短为12d,可以在保证堆肥产品品质的基础上显著提高堆肥效率,使南宫堆肥厂的垃圾处理能力得到大幅提高,该成果为南宫堆肥工艺优化的实施和改进及其推广应用提供了技术支持。     

翻堆工艺对0～15mm垃圾堆肥腐熟度空间变异影响研究

针对好氧堆肥高温发酵阶段堆体腐熟度差异大、空间存在变异的问题,以经北京市马家楼垃圾转运站筛分后的0-15mm生活垃圾为研究对象,在南宫堆肥厂隧道仓进行密闭式静态发酵试验。设计添加高温发酵阶段翻堆处理1次,与未经翻堆的处理进行对比,进行空间各种腐熟度指标测定及统计分析配对t检验。结果表明,未翻堆和翻堆物料的腐熟度指标经统计分析配对t检验,容重、pH值、EC、WSC、NH＋4-N、发芽率指数Pr值均小于0.01,差异极显著,含水率和E4/E6的Pr值小于0.05,差异显著;只有固相C/N的Pr值为0.445 5,大于0.05,差异不显著。高温发酵阶段进行翻堆处理,可以使堆体各处腐熟度均匀一致,空间变异性得到改善,同时可以明显促进微生物对垃圾的分解转化,加快垃圾的腐熟速度,提高堆肥产品的品质,为南宫堆肥厂提供了技术保障。     

Changes In Moisture Retention Properties Of Five Waste Materials During Short-Term Mesophilic Composting

The effect of composting for a maximum period of 90 days on the water retention characteristics of five waste materials — coconut dust (CD) (also known as coir), mixed sawdust (SD), rice hulls (RH), sapwood sawdust (SW) and heartwood sawdust (HW) was investigated with or without the addition of nitrogen. Total porosity (TP), easily available water (EAW) and water buffering capacity (WBC) were increased with time in all five materials, while air space (AS) was decreased in all the materials except in rice hulls, where it increased. Of all the materials, CD retained the most moisture and RH the least after 90 days. SD, SW and HW had similar characteristics, and separation for utilization is unnecessary. Nitrogen addition did not affect TP and AS but slightly increased EAW and WBC. Formulation and management of potting media using these materials should take into account these moisture retention changes for maximum benefit to plants grown in them.     

A Laboratory Method to Investigate Gaseous Emissions And Solids Decomposition During Composting Of Municipal Solid Wastes

A laboratory method was developed to quantify CO₂, NH₃ and VOC yields and to follow solids decomposition during composting of MSW or its components. All organic substrates were shredded, water and nutrients were added to near optimum levels prior to composting, and composting was continued until feed materials reached approximately the full extent of decomposition. Twenty five L stainless steel digesters were used and aluminum packing was mixed with the wastes to facilitate airflow. Thermophilic temperatures were maintained and air supplied in excess. Nutrients were added to reach an initial C/N ratio of approximately 30. CO₂ and NH₃ gases in the exit air stream were captured in alkaline and acidic solutions, respectively, and quantified through titration on a cumulative basis. VOC traps, prior to the gas traps, captured emitted volatile organic compounds, which were quantified on a cumulative basis. Solids were analyzed for hot water soluble matter, fats and lipids, cellulose, hemicellulose and lignin/humus. Food wastes, yard wastes and mixed paper produced approximately 368, 220 and 153 g C-CO₂/dry kg and approximately 40.5, 4.6 and 2.0 g N NH₃/dry kg of starting material, respectively. VOC volatilization profiles had a decreasing trend with composting. Partially composted MSW produced 8.2 mg/dry kg of 8 selected VOCs. CO₂, NH₃ and VOC recovery tests resulted in efficiencies of 98.6%, 97.6% and 94.6% respectively. Reproducibility of the solids decomposition and gaseous emissions measurements was observed. Carbon and nitrogen mass balance closures ranged from 85.5% to 117.1% and 32.2% to 175% respectively.     

RFLP法研究接种对农业废物堆肥微生物多样性的影响

用限制性片段长度多态性（Restriction fragment length polymorphism, RFLP）方法研究了在农业废物堆肥一次发酵和二次发酵期间添加黄孢原毛平革菌 （ P. chrysosporium ）对微生物多样性的影响。结果表明,在不同发酵期接种P. chrysosporium对堆肥进程的影响不同。3种典型的限制性内切酶Alu Ⅰ ,Ho Ⅲ和TaqⅠ在分析堆肥细菌微生物多样性的灵敏性上,Hae Ⅲ效果最好,AluⅠ次之,TaqⅠ则并不很适用于分析堆肥细菌微生物多样性。接种黄孢对堆肥细菌群落的影响非常显著且迅速,二次接种可起到巩固一次接种效果的作用。     

菌、热及菌热联合对垃圾堆肥腐熟的比较分析

为研究菌剂、余热及其联合作用对堆肥腐熟度的影响,采用强制通风静态堆肥系统,以现有堆肥工艺为对照（CK）,比较研究了添加菌剂（T1）、余热利用（T2）、添加菌剂并利用余热（T3）3种工艺垃圾对堆肥过程中腐熟度的影响。结果表明：从温度、pH、电导率（EC）、腐植酸光学特性（E4/E6）、水溶性碳（WSC）、固相C/N和发芽率指数（GI）来看,4个处理均达到腐熟;添加菌剂（T1）对EC、E4/E6、WSC、C/N和GI有显著影响;除E4/E6、WSC和C/N外,循环热风（T2）对其余腐熟度指标有显著影响,菌剂和余热的联合作用可显著提高堆肥的腐熟度,且二者对堆肥腐熟度的影响是一种协同作用。     

Elemental Analysis of Composted Source Separated Municipal Solid Waste

? Samples from composted source separated municipal solid waste were analyzed for 25 elements, including heavy metals and trace nutrients. The results were compared to a rural soil. The precision and recoveries for the various analytes using microwave digestion and atomic spectroscopic methods were determined. The recoveries ranged from 30 percent to 130 percent, depending on the analyte. The concentrations of the regulated elements were all well below proposed EPA 503 limits. The average values (mg/kg, dry weight) were 2.1(As), 1.2(Cd), 20(Cr), 173(Cu), <2(Hg), <22(Mo), 17(Ni), 92(Pb), <1(Se), and 395(Zn). The sampling strategy followed a two-stage nested design, allowing for assignment of the errors to the various sampling components. The average errors were 7.2% (samples), 3.5% (sub-samples), and 3.6% (replicates) for the compost, and 10.8% (samples) and 4.7% (replicates) for the rural soil. Reducing the grind size dramatically reduced the error between replicates. The implication of these errors, in terms of estimating the number of samples needed for analysis, is demonstrated.     

锌污染对猪粪堆腐过程中微生物群落的影响

利用Biolog微平板技术,对不同浓度重金属Zn影响下堆料微生物群落多样性进行了研究。结果表明,较低浓度Zn处理（Zn含量为400mg·kg^-1）的堆料升温快,高温持续时间长。微生物群落多样性指数和微生物群落主成分分析（PCA）指标均表明不同浓度重金属处理的堆料微生物群落有明显不同,Zn含量为400mg·kg^-1的堆料微生物活性高,有利于增加群落的丰富度和功能多样性,与Zn含量为1000mg·kg^-1的堆料、对照组堆料起分异作用的碳源主要为多聚物类和糖类。     

农村生活垃圾生物稳定预处理对渗滤液产生及污染潜力的影响

为从源头控制垃圾填埋场渗滤液污染,以广州市番禺区猛涌村生活垃圾处理示范基地为研究对象,以猛涌村中转站分选得到的有机垃圾为试验材料,采用生物稳定和淋溶试验研究方法,以未经生物稳定处理的垃圾淋溶试验模拟渗滤液产生为对照（CK）,以生物稳定预处理36d的垃圾淋溶试验模拟渗滤液产生为处理1（T1）,以生物稳定预处理12d的垃圾淋溶试验模拟渗滤液产生为处理2（T2）。通过分析渗滤液pH、氨氮、总磷、COD、水溶性碳等指标的变化,考察生物预处理方法对渗滤液的污染控制效果。结果表明,在10d淋溶试验过程中,T1、T2渗滤液产量比CK分别减少33、28;CK渗滤液pH一直呈酸性,而T1、T2介于在7.0～8.5;T1、T2渗滤液氨氮、总磷、COD、水溶性碳平均浓度分别比CK降低77、63,75、69,73、66,74、69,明显降低了垃圾的污染潜力,垃圾生物稳定程度越高,污染潜力越低。研究成果从生态控制的角度为垃圾填埋场渗滤液污染防治提供了理论依据。     

Fate and Transport of Organic Compounds in Municipal Solid Waste Compost

Four chemicals, polychlorinated biphenyls (PCB), benzo(a)pyrene (B(a)P), a-chlordane, and bisethylhexyl phthalate (BEHP), were chosen for investigation because of their range of physical/chemical properties and because they have been reported in municipal solid waste compost in the literature. Field studies were performed by applying amended compost, which was spiked with the four chosen organic chemicals, into corn, fescue, and poplar fields in Amana, Iowa.

The Pesticide Root Zone Model II (PRZM II), a U.S. EPA computer code (Dean, et al., 1989), was utilized to predict the potential fate and transport of four chemicals in the unsaturated zone. Model input consisted of meteorological records from nearby weather stations, soil data from the Amana site and laboratory results/literature values of chemical properties.

Results indicate that, due to their relatively low solubility and high hydrophobicity, the chemicals are quite sorptive to the soil/compost mixture and barely migrate vertically in the soil. In five year simulations, the chemicals remained within the rooting zone of the plants and slowly biodegraded. Plant uptakes were relatively small and essentially no leachate reached the groundwater table. Volatilization of PCB and chlordane was significant only for the top soil layer. A field study is being used to verify the modeling results.     

Cobiogasification of Wastepaper Products with Separately Collected Municipal Solid Waste

? The treatment of soiled hygiene papers (HYP), such as diapers and sanitary napkins, added at a concentration of 10 percent (w/w) to separately collected municipal biowaste was tested at Biotechnishce Abfallverwertung (BTA)'s three stage mesophilic biogas plant in Munich. The study aimed to establish the feasibility of cobiogasification of hygiene papers and biowaste. Parameters measured were: Efficiency of plastics and inerts separation; Mass balances; Organic and inorganic dry residues; COD; C:N ratio; Heavy metal content; Bacterial counts; Fiber analysis of suspension; Residues; Effluent for hemicellulose, cellulose and lignin; Biogas yield; and Quality. In the conditioning stage, the hygiene papers (HYP) (10 percent) were completely suspended with municipal solid waste. The dry materials balance of the conditioning unit resulted in an increase of 1.5 percent of the screenings, corresponding exactly to the amount of the added plastics. Heavy metal contents in the residues were well below limits established by German compost quality guidelines. Plate counts of the sums of Enterobacteriae and Salmonellae revealed that addition of soiled HYPs does not increase risk of contamination. Fermentation process and yield did not differ from control; biogas contained about 70-75 percent methane and most organic pollutants measured were undetectable.     

Wood Ash as an Amendment in Municipal Sludge And Yard Waste Composting Processes

Wood ash from a wood-fired, electrical generating plant was examined as a potential amendment in municipal biosolids and yard waste composting applications. The rate of composting and the final compost quality (chemical, physical, and plant growth characteristics) were examined. Yard waste (leaves, grass, and wood chips) and a municipal biosolids-chip mixture were either not amended or amended with wood ash at eight percent or five percent by weight, respectively, and then composted outdoors in insulated, 1700L, aerated reactors. Yard waste piles heated rapidly to 60°C within six to seven days, whereas biosolid piles heated more slowly to a maximum of 52 to 57°C within nine to 11 days. Ash had little, if any, effect on the time-temperature response. In general, ash-amended compost had higher pi I, plant nutrient, and salt contents. Tomato plants (Lycopersicum esculentum) produced 100 percent more shoot biomass in biosolids than in yard waste compost media. Poor plant growth in the yard waste compost was likely due to the high initial pH and salt content of the growth medium. In yard waste media, tomato plants germinated and produced more shoot biomass in the control compost than in the ash-amended compost.

A pH neutralization study indicated that wood fly ash could be used as an economical substitute for lime which is commonly used to stabilize municipal biosolids prior to land filling or land application. Wood fly ash (pH = 13.2-13.4), when added to biosolids at a 2 to 1 ratio by weight, raised the pH of the mixture to 12.0.     

Fingerprint of Exhaust Gases and Database of Microbial Diversity During Silkworm Excrement Composting

Composting can convert silkworm excrement (SE) into good fertilizer, but the popularization of this practice is greatly hampered due to the strong odor produced. Determining the gas pollutants, the potential native aerogenic microorganisms and deodorant microorganism communities will lay foundations for developing good strategies to deal with malodor pollution from SE composting. This study qualitatively and quantitatively analyzed the exhaust gas and the microbial diversity. With a combination of solid-phase micro-extraction-gas chromatography tandem mass spectrometry technology and other methods of Chinese national standards, 43 odor pollutants from SE composting were identified and quantified. Ammonia, sulfur dioxide and hydrogen sulfide were the three major pollutants among the volatile inorganic compounds, with concentrations far exceeding the permissible standards for workplaces in China. 5-Ethyl-2,2,3-trimethyl-heptane, 2,2,4,6,6-5-methyl-heptane and 5-isobutyl-nonane accounted for 46.58% of volatile organic compounds. Using analysis of ribosome DNA sequences with Illumina Miseq PE 2 * 250, a next generation high-throughput sequencing technology, more than 694 bacteria (and actinomycetes) and more than 136 fungi were annotated, including groups of native aerogenic microorganisms and deodorant microorganisms. This study indicated a serious malodor problem and abundant microorganisms from SE composting and provided basic data not only for odor pollution control but also for future functional microorganism studies.     

Non-Composted Municipal Solid Waste Processing Byproduct Effect on Soil Reclamation

ABSTRACT

A new garbage processing technology has been developed that sterilizes and separates inorganic and organic components of municipal solid waste. The non-composted byproduct of this process, Fluff®, has the potential to be utilized as a soil amendment to improve soil conditions in highly degraded soils. A study was initiated to evaluate Fluff as a soil amendment for establishing native grasses on disturbed US Army training lands. The Fluff was incorporated into a sandy loam soil at Fort Benning Military Reservation, GA on two sites: a moderately degraded and a highly degraded soil. The Fluff was incorporated at rates of 0, 18, 36, 72, and 143 Mg ha^{? 1} to assess the effects on soil properties for two growing seasons. The addition of Fluff improved available plant nutrients and soil pH levels at both sites. Also, Fluff reduced the level of soil bulk density and increased soil concentration of carbon (C) and nitrogen (N). Because no adverse environmental effects were detected and Fluff improved soil physical and nutrient conditions as well as improving perennial grass establishment with increasing application rates, land application of Fluff to degraded US Army training grounds could be considered a viable and beneficial alternative to current waste management practices.     

Effects of Municipal Solid Waste Compost on Soil Properties and Vegetables Growth

ABSTRACT

This work investigates the impact of municipal solid waste compost (MSW-compost) application (0, 50, and 100 t/ha) on the growth, and on nutrient and trace elements content in lettuce and tomato plants grown in large, 40-L pots. Our findings showed inhibition of plants’ growth with increasing dose of MSW-compost, compared to plants receiving conventional fertilization. Growth inhibition was associated with a sharp decrease in soil NO₃–N content. On the other hand, a slower decrease in soil NO₃–N content occurred in non-planted pots amended with MSW-compost. These findings provide evidence that N immobilization and/or decreased N mineralization were responsible for inhibited growth by constraining N availability. With regard to the other macro-nutrients, K, P, Mg, Ca, and Fe, their contents in leaves of both crops were maintained at optimum levels. Higher zinc and copper content was measured in leaves of both crops but they did not exceed the optimum range for growth. No accumulation of trace elements was found in the fruits. The content of heavy metals in the tissues of plants grown in MSW-compost amended soil, remained at levels similar to those of the non-amended soil, suggesting that they do not pose a significant risk either for plant growth or public health. The findings of our study suggest that further emphasis should be given on the investigation of the factors regulating N mineralization and availability in order to avoid reductions in crop yield.