Comparison of heavy metals content in compost against vermicompost of organic solid waste: Past and present

Disposal of the municipal organic solid waste is a serious problem worldwide. Composting is one of the most preferred methods of solid waste management practice, principally due to the high percentage of organic material in the waste composition. Composting has advantages over land-filling and incineration in Mauritius because of lower operational costs, less environmental pollution, beneficial use of the end product, high humidity and organic content of household waste. Vermicomposting is a comparatively enhanced method in composting, and involves the stabilization of organic solid waste through earthworm consumption that converts the waste into earthworm castings. In both composting and vermicomposting processes, the presence of heavy metals and different toxics substances limits its land use without processing. The production and application of compost potentially contaminate the environment with heavy metals. There is a high-degree of consensus in the past and present literatures that composting increases metal concentrations but whether similar changes in metal concentration and availability occur during vermicomposting has not been fully resolved. This review deals with various total metal contents present in composting compared to that present in vermicomposting of organic solid wastes from past and present years.     

Efficacy of vermicomposting for recycling organic portion of hospital wastes using <Emphasis Type="Italic">Eisenia fetida</Emphasis>: standardization of cow manure proportion to increase enzymatic activities and fungal biomass

Hospital wastes are infectious wastes generated in hospitals and need to be disposed in such a way that they do not spread disease. In this experiment, 5, 10, 15 and 20% cow manure (CM) were mixed with hospital wastes (HW), and mixed wastes were subjected to vermicomposting. In control treatment, only HW was used for vermicomposting. Results suggested that significantly (P ≤ 0.05) higher total nitrogen content was recorded in vermicomposts when 10% or more CM was added to HW. Higher mineralization rate (decrease in C/N ratio) and cellulase activity is probably responsible for rapid organic matter decomposition (loss of total organic carbon). Ergosterol content i.e., total fungal biomass and cellulolytic fungal population were almost constant initially, but increased in the latter stage of vermicomposting. All the vermicompost samples, prepared in this experiment, showed the absence of coliform bacteria. Therefore, it could be concluded that 10% CM addition with HW was the most economical to obtain best quality vermicompost in terms of nutrient content and microbial status.     

Recycling of spent mushroom compost using earthworms Eisenia foetida and Eisenia andrei

A 90-day study conducted to explore the potential of epigeic earthworms Eisenia foetida and Eisenia andrei to transform the different types of agricultural wastes and spent mushroom compost into value-added product, i.e., vermicompost. Vermicomposting resulted in significant reduction in C:N ratio, pH, electrical conductivity, total organic carbon, TK; and increase in total Kajeldahl nitrogen, TP, and various micro and macronutrients compared to those in the worm feed. Our trials demonstrated that the vermicomposting could be considered as an alternate technology for recycling and environmentally safe disposal/management of the mushroom cultivation complexes’ residues mixed with different types of agricultural waste using epigeic earthworms E. foetida and E. andrei.     

Exploring chemical analysis of vermicompost of various oil palm fibre wastes

The aim of this work was to study the physical and chemical properties of different oil palm wastes, viz. empty fruit bunch (EFB), oil palm frond (OPF) and oil palm trunk (OPT). A study (84 days duration) was conducted to evaluate the efficiency of an exotic earthworm species (epigeic-African Nightcrawler (Eudrilus euginae)) for the decomposition of different types of oil palm wastes (EFB, OPT and OPF) into valuable vermicompost. The decrease in earthworm’s biomass gain for EFB, OPT and OPF may be due to exhaustion of worm feed in vermicomposters. The percentage of nitrogen, phosphorous and potassium in vermicompost was found to increase while pH and total organic carbon declined as a function of the vermicomposting period. The vermicompost obtained showed an increase in heavy metal content for all the reactors, but levels were still in the range of nutrient in the vermicompost. The data reveal that vermicomposting (using African Nightcrawler) is a suitable technology for the decomposition of oil palm wastes, especially EFB into value-added material.     

我国医疗废物处理的现状及改进措施

医疗废物被列为《国家危险废物名录》的首位,处理不彻底会对水体、土壤、空气和人体造成严重危害。然而,我国对医疗废物的处理起步比较晚,和世界发达国家相比处于落后状态。目前,我国的医疗废物总量逐年增加,集中处理率低,收集、分类、贮存、运输不规范,并且缺乏有效的监管体系和运行机制,应该采取加强医疗废物源头控制、建立医疗废物监管体制、提高医疗废物处理技术和能力等措施,力争在较短的时间内彻底改变我国医疗废物处理现状。     

Beneficial reuse and sustainability: the fate of organic compounds in land-applied waste

Land application systems, also referred to as beneficial reuse systems, are engineered systems that have defined and permitted application areas based on site and waste characteristics to determine the land area size requirement. These terrestrial systems have orders of magnitude greater microbial capability and residence time to achieve decomposition and assimilation compared with aquatic systems. In this paper we focus on current information and information needs related to terrestrial fate pathways in land treatment systems. Attention is given to conventional organic chemicals as well as new estrogenic and pharmaceutical chemicals of commerce. Specific terrestrial fate pathways addressed include: decomposition, bound residue formation, leaching, runoff, and crop uptake. Molecular decomposition and formation of bound residues provide the basis for the design and regulation of land treatment systems. These mechanisms allow for assimilation of wastes and nondegradation of the environment and accomplish the goal of sustainable land use. Bound residues that are biologically produced are relatively immobile, degrade at rates similar to natural soil materials, and should present a significantly reduced risk to the environment as opposed to parent contaminants. With regard to leaching and runoff pathways, no comprehensive summary or mathematical model of organic chemical migration from land treatment systems has been developed. For the crop uptake pathway, a critical need exists to develop information for nonagricultural chemicals and to address full-scale performance and monitoring at more land application sites. The limited technology choices for treatment of biosolids, liquids, and other wastes implies that acceptance of some risks and occurrence of some benefits will continue to characterize land application practices that contribute directly to the goal of beneficial reuse and sustainability.     

How does the operational environment affect utility performance? A parametric study on the waste sector

The urban waste treatment service has been a sensitive issue for the Portuguese governments in the past decades. Among other measures, the environmental and economical issues led to the creation of a sector-specific regulator for the waste sector. Considering this atypical circumstance in the worldwide context it is worth studying the external factors that may influence the waste utilities efficiency along with the regulation role. In this regard, we applied the parametric approach of the stochastic frontier analysis to evaluate the influence of the operational environment on the urban waste services performance. The sample included 32 utilities responsible for the waste treatment service in Portugal. The results showed a negative influence of factors, such as the existence of regulation, the distance to the waste treatment facilities and the provision of other services on utility performance. We also observed some benefits from privatisation and incineration, although these options have some particular features.     

Management of biomass residues generated from palm oil mill: Vermicomposting a sustainable option

Solid waste management is one of the challenging problems worldwide and it is becoming more complex by the increase in population and subsequently the waste generated. In Malaysia, among industrial solid waste palm oil mill waste (POMW) contributes the highest share. Wastes from the oil palm mill includes palm oil mill effluent (POME), decanter cake, empty fruit bunches, seed shells and the fibre from mesocarp. Generally most of the waste generated is either disposed of via open dumping or used as fertilizers as such or as animal feed. Land application of POMW and POME is very common practice as it contains numbers of plant nutrients. Direct application of POMW into agricultural soil can result in a number of problems such as water pollution, leaching etc. To deal with these problems, vermicomposting of palm oil mill waste may be a sustainable waste management option.There are number of researches going on management of biomass residues from palm oil mill, but very few works are going on vermicomposting of these agro-industrial waste. Vermicomposting of POMW can be a good practice as it will also be helpful in recycling the useful plant nutrients and it is better than that of composting process. Present review deals with the various aspects of vermicomposting of POMW and its importance. Review also put forward the effect of potential application of vermicompost on plant growth. On the whole it looks for the possibility of vermicomposting of waste from palm oil mill as a sustainable waste management alternative.     

Recovery of biomass wastes by hydrolysis in sub-critical water

The recovery of waste substances is important not only for the prevention of environmental issues, but also for the rational utilization of natural resources. Hydrolysis reaction in sub-critical water is a promising method for the treatment of organic wastes and has been attracting worldwide attention. In this paper, sub-critical water hydrolysis was employed as a method for producing amino acids, reducing sugars, bio-oil and gas fuels from biomass wastes. The current statuses of these useful chemicals production from biomass wastes by hydrolysis in sub-critical water were reviewed. The review indicates that sub-critical water hydrolysis can be an efficient process for recovering useful chemicals from biomass wastes. This method is renewable, sustainable, efficient, and safe for the environment.     

A CLOSED WATER REUSE SYSTEM FOR POWER PLANT COOLING AND DIGESTER HEATING1

ABSTRACT: A model consisting of closed water reuse and productive use of various types of wastes for energy generation is presented. The sewage after treatment would be used as the cooling water for power plants, and the condenser discharge therefrom be used as heating water for sludge digesters. The water is then purified for municipal water supply for continuous use. The advantages of this system are that water resources and energy are conserved while various types of wastes including waste heat are controlled. With a preliminary system analysis, it appears that the design for power plant based on the total heating value of wastes and digester capacity based on sewage sludge generation is feasible in terms of acquisition and full utilization of various types of wastes as generated in a single metropolitan area. The system as shown in this design is in balance among various factors such as the generation rate of municipal refuse, municipal sewage, waste heat in the condenser discharge, and raw sewage sludge.     

Biosolid colloid-mediated transport of copper, zinc, and lead in waste-amended soils

Increasing land applications of biosolid wastes as soil amendments have raised concerns about potential toxic effects of associated metals on the environment. This study investigated the ability of biosolid colloids to transport metals associated with organic waste amendments through subsurface soil environments with leaching experiments involving undisturbed soil monoliths. Biosolid colloids were fractionated from a lime-stabilized, an aerobically digested, and a poultry manure organic waste and applied onto the monoliths at a rate of 0.7 cm/h. Eluents were monitored for Cu, Zn, Pb, and colloid concentrations over 16 to 24 pore volumes of leaching. Mass-balance calculations indicated significantly higher (up to 77 times) metal elutions in association with the biosolid colloids in both total and soluble fractions over the control treatments. Eluted metal loads varied with metal, colloid, and soil type, following the sequences Zn = Cu > Pb, and ADB > PMB > LSB colloids. Colloid and metal elution was enhanced by decreasing pH and colloid size, and increasing soil macroporosity and organic matter content. Breakthrough curves were mostly irregular, showing several maxima and minima as a result of preferential macropore flow and multiple clogging and flushing cycles. Soil- and colloid-metal sorption affinities were not reliable predictors of metal attenuation/elution loads, underscoring the dynamic nature of transport processes. The findings demonstrate the important role of biosolid colloids as contaminant carriers and the significant risk they pose, if unaccounted, for soil and ground water contamination in areas receiving heavy applications of biosolid waste amendments.     

Long-term performance of a land treatment facility for the bioremediation of non-volatile oily wastes

The current study reports on operational and performance aspects of a land treatment facility for managing oily wastes generated from heavy vehicle maintenance over a 5-year period. Samples of soil and groundwater from the land treatment plots were analyzed for a range of contaminants and microorganisms over this period. The soil analyses indicated that the process has been operating efficiently even at high wastewater loadings with maximum degradation rates of 250 mg/kg per day (year 1) and average rates of 10–35 mg/kg per day (years 2–5). Hydrocarbon degraders comprised more than 80% of the total (measured) soil heterotrophic population and were present at 10⁶–10⁸ (per gram soil) once the process was optimized. The facility was capable of treating 140 kl of oily wastewater per day (average petroleum hydrocarbon content of 2% w/v) over the entire period. During this time there was no evidence of accumulation of any major metals or polycyclic aromatic hydrocarbon (PAH) compounds in the soil. Groundwater sampling and analysis indicated that the land treatment facility was not leading to contamination of any groundwater taken from bores in the vicinity of the facility. The land treatment process continues to be effective for treatment of non-volatile waste oils at this remote and high evaporation (arid) site.     

钻井固化土资源化利用技术研究

文章采用固化土资源化利用技术对钻井固化土进行处理。该技术采用钻井固化土为原料,用砂石作为骨料,通过高效固土复合材料的研制和固化土处置配方的优选实验得到满足强度要求的建筑材料,实现固化土的再利用。目前该技术已经在元坝六井井场内部修筑约300m2的护坡。现场结果表明,应用效果较好,节约成本,经济效益较大,且能满足相关质量要求,在很大程度上解决了固化土的处置问题,为钻井废物的无害化、资源化利用提供了技术参考。     

An overview on biogas generation from anaerobic digestion of food waste

Food waste is an inevitable type of waste in every city, and its treatment technology evolves with time. Due to the high organic content and high biodegradability of food waste, anaerobic digestion becomes a commonly accepted treatment method to deal with it. This review article summarizes key factors for anaerobic digestion and provides useful information for successful anaerobic digestions. Reasonable temperature and pH are essential for a successful and productive anaerobic digestion process. A good inoculum to substrate ratio triggers a profitable food waste digestion. Good mixing and small particle sizes are important factors too. In addition, the pros and cons of different reactors to food waste digestion are highlighted. Moreover, co-digestion of food waste with animal manures, sewage sludge, and green waste were introduced.     

Health-care waste management in India.

Health-care waste management in India is receiving greater attention due to recent regulations (the Biomedical Wastes (Management & Handling) Rules, 1998). The prevailing situation is analysed covering various issues like quantities and proportion of different constituents of wastes, handling, treatment and disposal methods in various health-care units (HCUs). The waste generation rate ranges between 0.5 and 2.0 kg bed-1 day-1. It is estimated that annually about 0.33 million tonnes of waste are generated in India. The solid waste from the hospitals consists of bandages, linen and other infectious waste (30-35%), plastics (7-10%), disposable syringes (0.3-0.5%), glass (3-5%) and other general wastes including food (40-45%). In general, the wastes are collected in a mixed form, transported and disposed of along with municipal solid wastes. At many places, authorities are failing to install appropriate systems for a variety of reasons, such as non-availability of appropriate technologies, inadequate financial resources and absence of professional training on waste management. Hazards associated with health-care waste management and shortcomings in the existing system are identified. The rules for management and handling of biomedical wastes are summarised, giving the categories of different wastes, suggested storage containers including colour-coding and treatment options. Existing and proposed systems of health-care waste management are described. A waste-management plan for health-care establishments is also proposed, which includes institutional arrangements, appropriate technologies, operational plans, financial management and the drawing up of appropriate staff training programmes.     

ENVIRONMENTAL IMPACT EVALUATION OF HAZARDOUS WASTE DISPOSAL IN LAND1

Since the publication of Rachel Carson's Silent Spring in 1962 there has been a rapidly growing public concern over widespread contamination of the environment with hazardous wastes. In recent years scientific findings on the ecological effects of various hazardous substances have posed several important questions. What exactly are hazardous wastes? Can these substances be disposed of in a technically feasible, economical, and safe way with assurance that they have been permanently eliminated from the ecosystem? What compositional alterations or movements of the hazardous wastes occur in water, soil, or air systems? What effect will these wastes have on the water, soil, or air systems? What effect will these wastes have on the water, soil, or air properties? Consequently, a University of Louisville study has developed a relevant definition of hazardous wastes for the Environmental Engineering profession together with priority of concern rating systems to delineate the degree of environmental impact imposed on a total ecosystem by a hazardous waste and the feasibility of disposing of hazardous substances at specific landfill sites. It is felt that refinements of the priority of concern rating systems offered here may provide a sound basis from which procedural decisions may be structured to establish future national hazardous waste disposal sites.     

Relation Between Edaphic Factors and Vegetation Development on Copper Mine Wastes: A Case Study From Bor (Serbia,SE Europe)

The relationship between edaphic characteristics and vegetation growing on mine wastes in the Bor region (East Serbia, SE Europe) was studied using multivariate statistical analysis. The influence of edaphic factors on the composition of plant life-forms was also investigated, since it could reflect strategies for the avoidance of or tolerance to disturbances of ecosystems. The goal was to provide potential models for the restoration and management of this and similar mine waste areas. The results of this study imply that soil textures, nitrogen contents, reclamation technology and the presence of hydrothermally altered andesite as the type of bedrock significantly influenced plant colonization and vegetation composition of the Bor mine wastes. These edaphic factors explained 30.3 % of the total variation in the vegetation data set. It was also revealed that the pattern of plant life-forms found on the considered site groups corresponded to the soil texture. Based on their relative abundance on the investigated sites and relationships with soil properties it is concluded that therophytes and geophytes are unsuccessful primary colonizers of the Bor mine wastes. Hemicryptophytes of psammophytic character were the most successful primary colonizers and therefore potential candidates for anthropogenically-assisted natural recovery. This study suggested that an assessment of edaphic factors should be widely used in the characterization of mine wastes prior to reclamation. Estimation of their role in the development of existing mine vegetation should predate reclamation procedures. Thus, approaches based on adequate plant life-forms should have a more prominent role in future mine reclamation schemes.     

Production of vermifertilizer from guar gum industrial wastes by using composting earthworm <Emphasis Type="Italic">Perionyx sansibaricus</Emphasis> (Perrier)

Efforts have been made to convert the guar gum industrial waste into a value-added product, by employing a new earthworm species for vermicomposting e.g. Perionyx sansibaricus (Perrier) (Megascolecidae), under laboratory conditions. Industrial lignocellulosic waste was amended with other organic supplements (saw dust and cow dung); and three types of vermibeds were prepared: guar gum industrial waste + cow dung + saw dust in 40: 30: 30 ratio (T₁), guar gum industrial waste + cow dung + saw dust in 60: 20: 20 ratio (T_2,), and guar gum industrial waste + cow dung + saw dust in 75: 15: 10 ratio (T₃). As compared to initial concentrations, vermicomposts exhibited a decrease in organic C content (5.0–11.3%) and C:N ratio (11.1–24.4%) and an increase in total N (18.4–22.8%), available P (39.7–92.4%), and exchangeable K (9.4–19.7%) contents, after 150 days of vermicomposting. A vermicomposting coefficient (VC) was used to compare of vermicomposting with the experimental control (composting). P. sansibaricus exhibited maximum value of mean individual live weight (742.8 ± 21.1 mg), biomass gain (442.94 ± 21.8 mg), growth rate (2.95 ± 0.15 mg day⁻¹), cocoon numbers (96.0 ± 5.1) and reproduction rate (cocoons worm⁻¹ day⁻¹) (0.034 ± 0.001) in T₂ treatment. In T₃ maximum mortality (30.0 ± 4.01 %) in earthworm population was observed. Overall, T₂ vermibed appeared as an ideal substrate to manage guar gum industrial waste effectively. Vermicomposting can be proposed as a low-input basis technology to convert industrial waste into value-added biofertilizer.     

Hospital waste management in El-Beheira Governorate,Egypt

This study investigated the hospital waste management practices used by eight randomly selected hospitals located in Damanhour City of El-Beheira Governorate and determined the total daily generation rate of their wastes. Physico-chemical characteristics of hospital wastes were determined according to standard methods. A survey was conducted using a questionnaire to collect information about the practices related to waste segregation, collection procedures, the type of temporary storage containers, on-site transport and central storage area, treatment of wastes, off-site transport, and final disposal options. This study indicated that the quantity of medical waste generated by these hospitals was 1.249 tons/day. Almost two-thirds was waste similar to domestic waste. The remainder (38.9%) was considered to be hazardous waste. The survey results showed that segregation of all wastes was not conducted according to consistent rules and standards where some quantity of medical waste was disposed of with domestic wastes. The most frequently used treatment method for solid medical waste was incineration which is not accepted at the current time due to the risks associated with it. Only one of the hospitals was equipped with an incinerator which is devoid of any air pollution control system. Autoclaving was also used in only one of the selected hospitals. As for the liquid medical waste, the survey results indicated that nearly all of the surveyed hospitals were discharging it in the municipal sewerage system without any treatment. It was concluded that the inadequacies in the current hospital waste management practices in Damanhour City were mainly related to ineffective segregation at the source, inappropriate collection methods, unsafe storage of waste, insufficient financial and human resources for proper management, and poor control of waste disposal. The other issues that need to be considered are a lack of appropriate protective equipment and lack of training and clear lines of responsibilities between the departments involved in hospital waste management. Effective medical waste management programs are multisectoral and require cooperation between all levels of implementation, from national and local governments to hospital staff and private businesses.     

Repeated compost application effects on phosphorus runoff in the Virginia Piedmont

Increasing amounts of animal and municipal wastes are being composted before land application to improve handling and spreading characteristics, and to reduce odor and disease incidence. Repeated applications of composted biosolids and manure to cropland may increase the risk for P enrichment of agricultural runoff. We conducted field research in 2003 and 2004 on a Fauquier silty clay loam (Ultic Hapludalfs) to compare the effects of annual (since 1999) applications of composted and uncomposted organic residuals on P runoff characteristics. Biosolids compost (BSC), poultry litter-yard waste compost (PLC), and uncomposted poultry litter (PL) were applied based on estimated plant-available N. A commercial fertilizer treatment (CF) and an unamended control treatment (CTL) were also included. Corn (Zea mays L.) and a cereal rye (Secale cereal L.) cover crop were planted each year. We applied simulated rainfall in fall 2004 and analyzed runoff for dissolved reactive P (DRP), total dissolved P (TDP), total P (TP), total organic C (TOC), and total suspended solids (TSS). End of season soil samples were analyzed for Mehlich-3 P (M3P), EPA 3050 P (3050P), water soluble P (WSP), degree of P saturation (DPS), soil C, and bulk density. Compost treatments significantly increased soil C, decreased bulk density, and increased M3P, 3050P, WSP, and DPS. The concentration of DRP, TDP, and TP in runoff was highest in compost treatments, but the mass of DRP and TDP was not different among treatments because infiltration was higher and runoff lower in compost-amended soil. Improved soil physical properties associated with poultry litter-yard waste compost application decreased loss of TP and TSS.