Utilization of lignocellulosic plant residues for compost formation and its role in improving soil fertility

Globally, urbanization and a steady increase in population generate a huge amount of wastes, which leads to a series of economic, social, and environmental changes, mainly in developing countries. There is an utmost need for efficient management strategies for the beneficial utilization of these wastes into useful products. Among these strategies, composting is gaining attention due to its benefits of solid waste management, such as proper sterilization, and economical and effective bioconversio...     

Cocomposting of Night Soil and Green Wastes

The feasibility of cocomposting night soil and green wastes (leaves, reed, and grass) and the optimum proportion required to obtain high quality compost for application in Beijing's Olympic Forest Park is investigated. Subsequently, an evaluation of the feasibility of zero discharge of night soil and green wastes was performed. Composting is conducted in three identical 100 L lab vessels. The night soil is mixed with green wastes at three different ratios (4:1, 3:1, and 2:1, night soil:leaves, w:w; 4:1, 3:1, and 2:1, night soil:reed, w:w; 0, 1:3, and 1:1, night soil:grass, w:w;). The mixtures were processed by aerobic composting. Cocomposting was realized at the night soil and leaf mixture ratios of 4:1 and 3:1, with the latter as the best ratio. For the night soil and grass mixture ratios of 0, 1:3, and 1:1, 1:3 is the best ratio while for the night soil and reed mixture ratios of 4:1 and 3:1, the best ratio is 4:1. Based on the annual amount of green wastes (approximately 360 tons of reeds, 1,250 tons of leaves, and 690 tons of grass) and night soil (approximately 300 tons) produced in Beijing's Olympic Forest Park, zero discharge for night soil can be realized through cocomposting. However, this is not the case for green wastes, especially leaves and reeds.     

园林废弃物不同处理方式的环境影响及其产物还田效应

针对城市园林废弃物数量日趋增多及资源化利用程度低的问题,该研究比较了园林废弃物在直接焚烧、好氧堆肥、热解碳化3种处理方式下的养分与碳素与氮磷钾损失、温室气体排放,以及相应产物还田对土壤物理化学性质的影响。结果表明,焚烧处理的有机碳损失率高达98.62%,分别比好氧堆肥、碳化处理高39.77%和41.64%;全氮损失率高达95.51%,显著高于好氧堆肥（22.72%）及碳化（36.65%）处理;3种处理全磷及全钾损失率的差异相对较小。焚烧处理的CO2排放量高达1271.62 g/kg,远高于好氧堆肥的210.71 g/kg,但两者CH4、N2O的排放量都相对很小。园林废弃物堆肥及碳化后还田均可促进土壤中小团聚体向大团聚体转化,提高土壤中毛管孔隙度和饱和导水率,并显著提高N、P、K含量;其中生物炭还田可显著提高土壤有机碳含量,好氧堆肥还田能降低土壤pH值。焚烧后的灰分还田除提高土壤P、K养分含量及大粒径团聚体外,其他效果不明显。综上所述,好氧堆肥和碳化是适用于城市园林废弃物处理的2种技术,研究结果可为城市园林废弃物资源优化处理利用提供参考。     

The Importance of Chelation in Composting: A Historical Perspective

? Much more research is presently being done on composting organic wastes than on humification in the soil. Humus research has therefore been reincarnated in the form of composting research. However, chelation is a neglected but important chemical reaction in composting and the utilization of compost as a soil amendment, just as it has been in soil formation and soil fertility. Research is needed to clarify the role of chelation in composting. It is also important to recognize the limitations in interpreting results from compost research in which the role of chelation was not considered.     

Regional Inventory of Organic Industrial Wastes: Case Study in New Brunswick,Canada

? This study was undertaken to investigate the possibility of composting organic industrial wastes which are currently being generated in the Canadian province of New Brunswick. Four types of this waste stream were identified: Fish wastes; Agricultural wastes; Pulp and paper and sawmill wastes; and Food processing wastes. Other objectives of this study were to establish valid cost estimates of selected solid waste composting approaches and to address the potential of a value-added compost product.

In the past 20 years, fish landings in the province averaged approximately 136,000 metric tons annually. Processing in fish transformation plants leads to fresh and pickled fish wastes that must be either discarded by dumping or processed into usable byproducts.

Animal manure is the principal waste currently being generated by the agricultural industry with 1,333,000 metric tons of manure produced in 1986. There are also approximately 90,000 metric tons of potato culls produced by the potato industry per year. Most of these agricultural wastes are presently being used or applied on land.

The forest industry is the biggest in New Brunswick and as such produces the largest amount of industrial wastes. Wood residues are generated in two sectors of the forest industry: Logging and Wood Processing organizations.

The food processing industry is a diversified enterprise processing items such as fruit products, vegetable products and meat products. Potato processing companies produce one of the most significant vegetable wastes of the province, with about 50,000 metric tons of wastes annually.     

Use of urea to correct immature Urban composts for agricultural purposes

Abstract

Municipal solid waste composts are often inadequately stabilized for agricultural purposes. In addition, compost quality may be even more reduced by loss of nitrogen (N) during the composting process. We have utilized a compost with a high content of soluble sugars (11 mg g^‐1, DM, indicating immaturity) and a low ? concentration (0.95%, DM). The compost had a low level of heavy metals. Results obtained in a germination bioassay conducted with cress, ryegrass and sunflower in a compost‐sand mixture reflected the immaturity of the compost. Such composts should be fortified with ? (in a complete fertilizer, when possible), at the same time avoiding an intimate contact with the soil (e.g., plowing down). When the compost (and raw wastes and wastes at the 4th week of composting) was mixed with a soil at a heavy rate (2.5 % w:w), ryegrass seedling emergence in pots was not affected, but the plantlets’ fresh weight in the compost treatment was significantly lower than that in the control (soil) and lower than that in the raw wastes, probably due to the lower ? concentration. As expected, plantlet fresh weight was notably increased by the combination of compost and wastes with a complete fertilizer. The application of compost in combination with a complete fertilizer or urea did not affect either dry matter production or nutrient uptake of ryegrass, despite the combination's being applied just at sowing (in pots). Results obtained in these experiments indicate that combining immature composts with urea [supplemented with phosphorus (P) and potassium (K), when possible] at a ratio of about 50:1 (about 200 kg urea per 101 compost) could be sufficient to prevent negative results in crop establishment. Such practices could contribute to overcoming the limited fertilizing capacity of the composts.     

国内外堆肥标准分析及其对中国的借鉴启示

中国农业废弃物产量巨大,堆肥是农业废弃物资源化利用的主要方式之一,也是养分和有机质回收到土壤中的方法。结合国内外堆肥标准制定情况,通过分析对比无害化指标、有机质、总养分、重金属、含水率等指标,指出中国存在就农业废弃物处理缺乏专业化堆肥及有机肥标准推进委员会、对堆肥产品中氮磷钾和有机质含量的最低限值较高及未建立堆肥标准体系等问题。建议国家组建堆肥标准制定专家委员会或堆肥协会,进一步规范有机肥生产运行管理,进一步修订有机肥、生物有机肥、沼肥等标准,建立完善的堆肥标准体系。     

Effects of Amendment of Calcimagnesic Soils With Olive Husk Compost In Tunisia

The amounts of olive husks produced in Mediterranean countries are very significant. Their treatment and disposal are becoming serious environmental problems. Increasing attention has been paid to finding a use for olive husks. A technological treatment is available to reduce their pollutant effects and to transform them into valuable products. The most suitable procedures are recycling instead of the detoxification of these wastes. It is possible to transform olive husks into organic fertilizers (composts) by composting with poultry manure. The compost has no phytotoxicity and may improve soil fertility and plant production. The composting process involves the microbial degradation of the polluting load of the solid wastes. Results of experiments using olive husk composts in crop production have shown that yields obtained with organic fertilization are similar, and sometimes higher, than those obtained with classic manure. Their bioavailability may be linked to the soil humic complexes originated by these organic fertilizers and to mineral components (active lime and clay). The composition of vegetable leaves improved similitude between compost and manure, normal concentrations but with deficiency in nitrogen, phosphorus and potassium.     

The disposal of leather tannery wastes by land treatment—a review

Abstract. People in rural areas have disposed of their wastes on land for centuries, relying on the soil's ability to degrade and render harmless any toxic elements the wastes may contain. Leather tanneries produce a large amount of sludge and liquid wastes. The liquids contain much sodium and in most circumstances adversely affect both the soil and groundwater. However, in some countries they are used for irrigation. The sludges contain nitrogen, calcium, magnesium, phosphorus, trivalent chromium and some sodium. Given careful management these sludges can be used as soil amendments, either directly or after composting. Application rates of about 200 tonnes ha⁻¹ have proved toxic to crops in pot trials, though larger applications than this have not adversely affected crops in the field. Much smaller rates, of less than 20 tonnes ha⁻¹, have been used in the field to minimize nitrate contamination of groundwater. The effects of CrIII depend on complex interactions between the sludge, the soil to which it is added and the plant species grown. Safe limits for the disposal of the sludges and their long term effects are not known.     

Needed: Regional Inventories of Organic Residuals

? As waste management planners seek to divert increasing amounts of materials from the municipal and commercial streams, the value of regions conducting inventories of organic residuals that could be composted becomes apparent. Since 1960, various research studies have analyzed the potential for applying urban wastes on agricultural lands, either directly or after composting. Specific studies described in this report were conducted in New Jersey, Maine and the Omaha, Nebraska — Council Bluffs, Iowa region.     

Paper Mill Sludge Composting and Compost Utilization

Economically viable and environmentally acceptable methods to recycle organic wastes are needed by the pulp and paper industry. We assessed the potential for composting the Virginia Fibre Corporation's (VFC) combined primary and secondary dewatered paper mill sludge (PMS) and evaluated the suitability of the finished product as a potting soil substitute. Composting treatments were: 1) PMS with no supplemental N (control), 2) PMS + 15 kg N/Mg PMS (dry weight), and 3) PMS + 30 kg N/Mg PMS (dry weight). Composting was conducted for 129 days and treatment effects were evaluated by windrow temperature trends. A container plant growth study employing various particle size fractions and proportions of the control PMS compost and a commercial potting medium (Promix^tm) was conducted in a greenhouse to assess the capability of the compost to support growth of radish (Raphanus sativus L.), snap bean (Phaseolus vulgaris L.), marigold (Tagetes erecta L.), and green pepper (Capsicum sp.). Windrow temperatures were lower with no supplemental N than with the N additions during the initial three weeks and were higher with increasing N rate during the last month of composting, which indicated that the unamended sludge may have been N-limited for maximum biological activity. Reduced temperatures in the high N treatments during the midpoint of the composting process may have been induced by ammonia toxicity. However, cured compost chemical properties and stability were not influenced by treatment and were indicative of good quality compost. The lower amount of plant-available water and greater amounts of plant-available nutrients supplied by the compost than the commercial potting medium resulted in less dry matter produced by all plants except green pepper, whose higher nutrient needs were supplied better by the compost than the commercial potting medium alone. Therefore, the paper mill sludge compost may best be used as an organic fertilizer, soil amendment, or supplemental nutrient source for potting media, rather than as a potting medium alone.     

Operational Parameters for Composting Night Soil in Korea

Recently composting of organic wastes started to gain popularity in Korea. The purpose of this study was to investigate the effect of operational parameters on night soil composting. Operational parameters investigated included compost recycle ratio and temperature control. Lab-scale composting reactors were used in this study. At the recycle ratio of 10 percent, reduction of both volatile solids and moisture content was greater than that at the recycle ratio of 0 percent and 30 percent. This result means that composting reaction was the most active at 10 percent recycle ratio. Temperature control played a important role in the night soil composting process. The greatest decrease in volatile solids was observed when the temperature of composting process was set below 60°C. Also, the amount of CO₂ evolved was the greatest when the maximum temperature was set below 60°C. Kinetic study indicated that first order kinetics described volatile solids reduction very well.     

Changes in Availability of Plant Nutrients during Composting of Cow Manure with Poplar Leaf Litter

Safe management of animal and plant waste is one of the world's most important environmental challenges. Composting has been proposed as a useful technique for beneficially recycling wastes. This study showed that significant temporal changes in the nutrient availability occurred during the composting of cow manure with poplar leaf litter within 120 days. In particular, total C in the final compost was directly related to the addition of tree litter and inversely related to the time of composting, whereas extractable P and NO₃ increased with increasing amounts of tree litter and ammonium showed the opposite trend. During the later stages of the composting process higher concentrations of water soluble K, Ca, Mg, and Na were observed. The major benefit observed was that heavy metal concentrations initially present in the manure were significantly reduced during composting. Heavy metals in the final compost decreased in the order: Fe > Mn > Zn > Cu > Ni > Cd. The increased availability of plant nutrients following composting coupled with the lower extractability of heavy metals indicates that composting may be a sustainable option for agricultural waste recycling and increased productivity.     

Utilization of Municipal Solid Waste Compost: Research Trials at the Johnson City,Tennessee Facility

? In 1963, the Division of Health and Safety of the Tennessee Valley Authority (TVA) proposed construction and operation of a composting plant at some medium-sized city in the valley, primarily as a means of disposing of solid wastes, but also as a means of converting wastes into a material useful for erosion control, land reclamation and soil improvement. The U.S. Environmental Protection Agency (EPA) and the TVA cooperated in the operation of a composting plant at Johnson City, Tennessee from 1967 to 1971. An outdoor windrow process was used. Sewage sludge was incorporated with the MSW up to 20 percent of the total compost solids.

Johnson City compost was used in numerous demonstrations in eastern Tennessee and western North Carolina, starting in the fall of 1968. Replicated field plot experiments were also carried out at Muscle Shoals, Alabama and eastern Tennessee. This report reviews results of those demonstration studies, as well as analyses of material used for stripmine reclamation and for ash pond stabilization. The results were in papers published by agronomists on the TVA staff in the 1970s. Data over a 19-year period following compost application are reviewed for impact on crop yield, organic matter and nutrient supply.     

Determining Optimal Maturity of Compost Used for Land Application

A stable compost is needed in plant growth media. However, when compost is land applied, its effect is through the initiation and acceleration of microbial processes leading to the production of soil stabilizing agents.

It was proposed that there is an optimum degree of maturity of compost used for land application, a degree characterized by the reduction of the labile organic matter to a point when the material is relatively stable yet is still active enough to support an increased microbial activity in the soil.

The effect of composting time on the efficiency of municipal solid waste compost (MSWC) to improve soil structural properties, evaluated through laboratory indexes, is presented in this work. MSWC was sampled immediately following 24 hours precomposting in a Dano drum. Samples were taken throughout 60 days of windrow composting. The compost samples were mixed with a structure-impaired loess soil and incubated aerobically for 21 days. Hydraulic conductivity and residual turbidity, a measure of microaggregate stability, were measured in solutions of two SAR levels, five and 20. Compost application had a positive effect on these soil structural properties. The optimal activity was obtained for the compost sampled following seven to 14 days of windrow composting. Polysaccharide concentrations also followed a similar optimum curve. The peak concentration was found following 14 to 30 days old compost application.

The determination of the optimal maturity of composted municipal solid wastes is essential toward an efficient utilization of the compost, toward satisfaction of environmental constraints and for a cost-efficient operation of composting plants. The present preliminary study calls for more research in this field.     

自然村生产生活废弃物循环利用模式及其评价研究

农业农村生产生活废弃物循环利用是实现农村人居环境治理、提高资源利用效率的重要途径,对美丽乡村建设具有重要意义。该文以自然村为研究对象,采用层次分析法和模糊评价法相结合的方法,统筹考虑生产生活废弃物循环利用,构建了自然村生产生活循环技术模式评价指标体系,确定各项指标的权重,建立评价方法。以河北邢台市山区某村为例,针对其生产生活废弃物产生特点,构建生产生活废弃物循环利用体系,该村农业废弃物以果木剪枝、生活垃圾、生活污水、人畜粪尿等为主,通过构建以果木剪枝热解+炭基有机肥还田为纽带的循环利用模式,辅以污水处理利用技术,实现了废弃物能源化和就地肥料化利用。通过对该自然村循环利用模式进行实地评价验证,结果表明该自然村生产生活循环技术模式评分结果为优。该文为中国村镇废弃物循环利用技术模式选择、农村人居环境改善和农业绿色发展提供参考和借鉴。     

Chemical and microbiological parameters for the characterization of maturity of composts made from farm and agro-industrial wastes

Bioconversion of farm wastes with agro-industrial wastes into enriched compost is an important possibility in need of research. In this article, changes in chemical and microbiological parameters were evaluated to determine the maturity of composts prepared from mixture of farm and agro-industrial wastes over a period of 150 days. Seven different composts were prepared by using a mixture of different farm wastes with or without enrichment with rock phosphate (RP), agro-industrial wastes and the inoculation of microorganisms. As composting proceeded, the organic C, water-soluble C (WSC), bacterial and fungal counts decreased, whereas total N, P, electrical conductivity (EC) and actinomycetes count increased gradually. Our results suggest that WSC <1%, C:N ratio < 20, neutral pH and a decrease in bacteria and fungal counts, along with an increase in actinomycetes count and stability at the end of composting, may be accepted as an indicator of compost maturity. Changes in organic C, EC, total N and P concentrations over time also proved to be reliable indicators of the progress of the composting process for establishing stability and compost maturity. Addition of RP, agro-industrial wastes and inoculation of microorganisms showed potential in improving the N and P contents of the composts.     

One-Step Extraction Procedure as an Easy Tool for Monitoring a Full-Scale Composting Plant

ABSTRACT. Composting is an efficient technique for managing the increasing production of organic wastes since it transforms them into a valuable product that can be applied to soil to improve it. However, it is necessary to ensure the adequate properties of this product for a proper agricultural or environmental application. Various parameters have been proposed as estimators of the evolution of the composting process, nevertheless there is a lack of easy techniques with a wide application range for monitoring it. This study evaluated some parameters that can be used to test compost evolution in samples of composted sewage sludge under full-scale conditions. Total extractable carbon (TEC) by alkaline solution of sodium pyrophosphate, humic acids (HA), fulvic acids (FA), and the ratio of them (HA/FA) were obtained by a one-step extraction procedure. Results were compared with those obtained after an official extraction method for the same parameters. Total organic matter was calculated by calcination (TOM%). The objective was to assess the usefulness of the one-step extraction as an easy and cheap tool for monitoring the composting process. The results indicate that both extraction procedures show a statistically significant correlation between them and with TOM%. Therefore, TEC obtained by the one-step extraction procedure can provide useful information about the evolution of the composting process of compost samples with the easiest methodology.     

外源微生物对堆肥理化性质及酶活影响的研究

利用牛粪和稻草为原料进行堆肥实验,通过测定堆肥过程中的温度、含水率等物理、化学指标以及酶活性的变化,研究了接种外源微生物对堆肥过程的影响。结果表明,接种外源微生物比对照提前2d达到高温期,并且维持时间长。大肠杆菌数量及植物毒性比不接种大幅度降低,纤维素酶、脲酶、多酚氧化酶、过氧化氢酶均有所增加。说明接种外源微生物可以使堆肥中微生物数量增多,加速堆料中有机物的分解,加快堆肥腐熟,缩短堆肥反应的进程,对优化堆肥工艺具有重要的意义。     

添加菌糠对鸡粪-烟末堆肥腐熟度及污染气体排放的影响

为探索鸡粪-烟末混合堆肥体系合适的菌糠投入量,减轻堆肥过程中污染气体的排放,通过35 d的堆肥试验,设置3个菌糠投入量[0(CK)、5%、10%],研究鸡粪-烟末堆肥条件下添加菌糠对堆肥腐熟度和污染气体排放的影响。结果表明,堆肥处理堆体温度均能在55℃持续8 d以上,达无害化标准。与CK相比,添加5%、10%菌糠处理堆肥产品对作物生长无毒害作用,腐熟度得到有效改善,但均未达到腐熟标准;添加5%菌糠处理总有机碳(TOC)损失降低了2.39个百分点,总氮(TN)损失降低了8.92个百分点;添加10%菌糠处理TOC损失增加了0.27个百分点,但TN损失降低了11.89个百分点。综合考虑堆肥腐熟度、碳氮损失和环境效应,添加菌糠作为膨松剂能够提升堆肥腐熟度并减少污染气体排放,更有利于农业废弃物肥料化的可持续发展。