Composting Of <100 mm Fraction Of Municipal Solid Waste

A low cost solution for management of municipal solid waste in small municipalities was investigated; composting experiments were done using domestic waste. Particles >100 mm were removed, the screened substrate (<100 mm) was used for composting experiments on static piles. The results have shown that the size of waste does not affect composting. Though the inert material left greatly adds to the porosity, rainfall does not markedly affect the process; in fact excessive dryness gave the least stable end product, and total nitrogen, ammoniacal nitrogen and phosphorus content were the best pointers to the instability.     

Reaction Kinetic Model For Optimal Pyrolysis Of Plastic Waste Mixtures

Reaction kinetics at various temperatures for pyrolysis of mixtures of plastic waste [polyethylene(PE) and polystyrene(PS)] are modelled in terms of five types of pyrolysis reaction. The model development is based on the assumption that as plastic wastes are heated in a non-reactive environment they are decomposed homogeneously to various products of gas, oil and char by a first-order rate, irreversible reaction and isothermal condition. Among the five models, the type II model in which the activated polymer exists as an intermediate product is the most accurate in predicting the pyrolysis products of pure PE or pure PS. Also, for mixtures of plastics both type II and IV models can be used to explain the composition of pyrolysis products. Furthermore, from the analysis of variance (ANOVA), the mixing ratio and temperature are shown to be the parameters that have the greatest effect on the pyrolysis reaction of polymer waste mixture. The pyrolysis reaction time for the maximum oil production from PE-PS mixtures is shorter than for PE alone and approaches that of PS alone. Oil production increases with increase of PS content. The optimal temperature for maximum oil production is 600°C for the pyrolysis of 2:8, 5:5 and 1:0 mixtures (w/w) of PE and PS. Oil production for PS alone is constant when the pyrolysis is above 600°C.     

Practical Simulation Of Composting In The Laboratory

A closed incubation system was developed for laboratory simulation of composting conditions at the interior of a large compost pile. A conductive heat flux control system (CHFC) was used to adjust the temperature of the internal wall to that of the compost center and compensate for heat loss. Insulated small vessels (400 cm³) controlled by the CHFC system were compared with similar vessels maintained at 30°C (mesophilic) and 55°C (thermophilic), and with large vessels (10 000 cm³) with and without the CHFC. Compost temperature rose rapidly to a maximum within 2-4 days, then gradually decreased. In mesophilic treatments (no CHFC), temperature at the matrix center increased to a maximum of 36°C in the small vessel and 50°C in the large vessel, while temperature in both vessels reached 50°C with the CHFC. Microbial activity was maintained by allowing compost to self-heat and controlling temperature externally with the CHFC. Higher temperatures were sustained for longer periods in CHFC vessels than in vessels without the CHFC. Periodic mixing of the compost matrix increased temperature and CO₂ evolution. Small vessels were successfully used in laboratory simulation of field-scale composting of a soil/organic matrix containing TNT and RDX munitions. The small vessel system reduced subsample error in compost monitoring from that of the large vessels. The CHFC has particular utility in research requiring expensive chemicals or hazardous substances.     

Effects Of pH Control On Composting Of Garbage

Composting experiments of garbage were conducted by using a laboratory scale reactor under well controlled experimental conditions and the effects of pH control were quantitatively analysed. In the pH controlled experiment, lime was added to prevent pH decreasing below 7, especially at the early stage of composting. The degradation rate of organic matter in the pH controlled experiment was faster than that without. Nitrogen loss was enhanced by the control of pH value, but the amount of promotion was relatively small. The pH dependency on the activity of microorganisms, which contribute to the composting rate, was investigated by using a liquid medium containing glucose and proteins as nutrients. The optimum pH for the growth rate and the degradation activity of proteins of the microorganisms was in the range of 7-8, while the decomposition of glucose proceeded rapidly at an early stage of composting in a pH range from 6 to 9.     

Use Of Mixed Probability Distributions For The Analysis Of Solid Waste Generation Data

The issues associated with the statistical analysis of municipal solid waste generation patterns are addressed in this paper. A methodology for determining a mixed probability distribution for daily waste generation data is developed. This methodology is then applied to data from two Canadian municipalities.     

The Origins Of Municipal Solid Waste: II. Policy Options For Plastics Waste Management

Plastic items in some portions of municipal solid waste (MSW), particularly from households and restaurants, have long been viewed as a disposal problem and a symbol of a "throwaway society". There is no question that the amount of plastics in solid waste is growing. However, this observation alone should not cause an hysteria of public policies for the separate management of the plastics or any other portion of the waste. The amount of plastics, and the contribution of the items discarded, must be viewed holistically in setting a solid waste management policy. This paper questions the basis for some U.S. plastics waste policy proposals by reviewing recent U.S. data on the effect of plastics on waste reduction, and the fate of discarded plastics products. Some alternative future policy directions are also discussed.     

The Origin And Fate Of Volatile Trace Components In Municipal Solid Waste Landfills

The content of readily volatile halogenated hydrocarbons (chlorinated and chlorinated, fluorinated hydrocarbons (VCCs/CFCs)) and the BTEX aromatic substances (benzene, toluene, ethylbenzene and xylene) in municipal solid waste (MSW) was determined by two different methods. Moreover, the emission potential of these substances via the gas and leachate phase was investigated during the different biological degradation phases in the landfill. Trichlorofluoromethane (R11), dichlorodifluoromethane (R12) and dichloromethane (R30) were the dominating halogenated trace substances detected in the MSW. In the acid phase, with some VCCs/CFCs the emittance may take place up to 30% via the water phase. Hexane, benzene, and toluene could be detected in all tests. Toluene often occurred in relatively high concentrations in MSW. It could be shown that R11 degraded into dichlorofluoromethane (R21).     

Fate Of An Absorbent Gelling Material For Hygiene Paper Products In Landfill And Composting

A cross-linked polyacrylate polymer, referred to as absorbent gelling material (AGM), has been developed for use in hygiene paper products, such as infant diapers (nappies). The fate and effects of this polymer were studied in laboratory models of landfill and aerobic composting. Radiolabelled (¹⁴C) AGM was used to facilitate determination of fate and mass balance. Tests were conducted in 1201 reactors containing a mixture of solid waste and compost or solid waste only, and panty diaper pads. Controlled temperature and leachate recycle were used to accelerate the biological processes. AGM caused no adverse effects and most of the material remained associated with the diaper pad and surrounding waste. Very little AGM (less than 1%) biodegraded to CO₂/CH₄ under landfill conditions, while 2-4% appeared in leachate. The leachate was highly biodegradable aerobically. More of the AGM (6.4%) biodegraded to CO₂/CH₄ under aerobic composting conditions, while less than 1% appeared in leachate.     

Policy Barriers To 50% Diversion Of Municipal Solid Waste

A number of policy barriers must be addressed by the governments in Europe and North America which have adopted objectives of diverting from disposal something like 50% of the solid waste stream by means of reduction, re-use and recycling. These include: the need for clarification of responsibilities of all levels of government and of private sector product manufacturers and waste disposers; putting in place incentives for source separation; ensuring markets for recyclables; and allocating the increased cost of waste management. This paper reports on findings of a research project undertaken in 1991-92 on steps being taken by different jurisdictions to overcome such barriers.     

A Composting Study of Membrane-Like Polyvinyl Alcohol Based Resins and Nanocomposites

This study presents the effect of biodegradation, in a composting medium, on properties of membrane-like crosslinked and noncrosslinked polyvinyl alcohol (PVA) and nanocomposites. The composting was carried out for 120 days and the biodegradation of these materials was characterized using various techniques. The changes in the PVA resin and nanocomposite surface topography and microstructure during composting were also characterized. The results from the analyses suggest biodegradation of PVA based materials in compost medium was mainly by enzymes secreted by fungi. The results also indicate that the enzymes degraded the amorphous regions of the specimens first and that the PVA crystallinity played an important role in its biodegradation. The surface roughness of the specimens was seen to increase with composting time as the microbial colonies grew which in turn facilitated further microorganism growth. All specimens broke into small pieces between 90 and 120 days of composting as a result of deep biodegradation. Glyoxal and malonic acid crosslinking decreased the PVA biodegradation rate slightly. Addition of highly crystalline microfibrillated cellulose and naturally occurring halloysite nanotubes in PVA based nanocomposites also decreased the biodegradation rate. The three factors: PVA crystallinity, crosslinking and additives, may be utilized effectively to extend the life of these materials in real life applications.     

Use Of Peat Extract In The Ensiling Of Fisheries Wastes

Fish processing wastes, namely minced cod (Gadus morhua) offal and minced male capelin (Mallotus villosus), were used in two kinds of ensiling (silage making) processes. In one process they were ensiled by the direct addition of acids, and in the other they were ensiled using various carbohydrate sources and bacterial cultures to produce organic acids in situ. Ensiled material was analysed for various components at times throughout its storage period, and monitored for onset of spoilage. It was found that neither prior freezing nor initial heat treatment of capelin had an effect on the preservation effectiveness of the ensiling process. It was concluded that both the addition of formic acid to cod offal and the fermentation of lactic acid bacteria are effective methods of ensiling this material. Peat extracts with a relatively high carbohydrate content were found to be a satisfactory source of carbohydrates for the fermentation of lactic acid bacteria in cod offal silage. However, peat extracts with a relatively low pH were found to be unsatisfactory as a direct source of acid for ensiling.     

A Review Of The Management Of Radioactive Wastes In Medical Institutes

Amongst the waste from health care institutions, radioactive waste represents a special category since it cannot be modified or neutralized by any available conventional means. Accordingly, disposal of radioactive waste can mean only its transfer from a place where it represents some hazard to somewhere else where it can be retained without undue risk. Radioactive waste arises in health care institutes as a result of diagnostic, therapeutical or research uses of unsealed radioactive substances. Sometimes, sealed sources withdrawn from further use might also be subject to disposal. Most radionuclides used in medicine are short-lived beta-, or beta-gamma emitters and represent a low risk, if properly handled, that is if due care is taken to prevent significant contamination of the workplace and personnel. Low-activity gaseous and liquid waste can usually be discharged to the environment directly; medium-activity or high-activity waste should be stored for variable periods to allow natural decay before specialized disposal.This paper presents a review of the different types of radioactive wastes produced in hospitals, and introduces many of the sources of generation and subsequent disposal options. An example is given of the wide range of guidance available, both by national bodies in Hungary and international agencies, such as the International Atomic Energy Agency (IAEA), World Health Organisation (WHO) and International Committee on Radiological Protection (ICRP).     

The Market for Waste Vitrification Technology

Waste vitrification technology has largely been developed by the United States Department of Energy (DOE). Numerous vendors offer vitrification units, and a number of commercial and large pilot applications have been made. Nevertheless, the industry is still in its infancy and does not dominate any waste treatment niche. DOE funding of vitrification technology development is nearing an end, and DOE waste treatment is being privatized, with private bidders selecting the technologies and offering to treat wastes for a per-unit fee. Thus, the DOE market is shifting from a cost-plus, largely R&D environment to a fixed-fee environment in which vendors and waste treatment contractors must accept technological risks. Significant quantities of DOE waste are still uncommitted, but the number of vendors is larger than the market can possibly sustain. Domestic private sector opportunities are limited and vendors are looking to foreign markets with less mature treatment capacity and growing demand.     

Study of the Determination of the Ultimate Aerobic Biodegradability of Plastic Materials Under Controlled Composting Conditions

Several ISO standards for determining the ultimate aerobic/anaerobic biodegradability of plastic materials have been published. In particular, ISO 14855-1 is a common test method that measures evolved carbon dioxide using such methods as continuous infrared analysis, gas chromatography or titration and others (ISO 14855-1(2005.9)). This method is a small-scale test for determining the ultimate aerobic biodegradability of plastic materials, where the amounts of compost inoculum and test sample in one tenth comparing with that of ISO 14855-1. This method is well versed in ISO/DIS 14855-2 which the carbon dioxide evolved from test vessel is determined by gravimetric analysis of carbon dioxide absorbent. The focus of this study is to elucidate statistically the results of round robin test by seven countries used MODA, which were various deviations among the experiments.     

TPA下脚料合成增塑剂DOTP的脱色研究

简要介绍了对苯二甲酸（ＴＰＡ）下脚料合成对苯二甲酸二辛酯（ＤＯＴＰ）的工艺路线，着重探讨了深色ＤＯＴＰ的色泽处理方法，优选出物理－化学法作为最佳脱色方法，并确定了最佳操作条件。该法操作简便，产品收率高达８５．４２％，产品质量符合７０℃级电缆料的要求。     

The Handling And Disposal Of Residuals From The Treatment Of Urban Stormwater Runoff From Separate Storm Drainage Systems

Given the magnitude of stormwater runoff (from separate storm drainage systems) and its pollutional contribution, the treatment of stormwater would generate residuals in amounts equal to or in excess of the volume of sludge now generated by municipal wastewater treatment. The characteristics of stormwater runoff differ substantially from that of wastewater or combined sewer overflow (CSO) in several important parameters, most notably suspended solids (SS) and organic content. The increased SS content of stormwater runoff results in higher volumes of residuals and increased handling and disposal costs. Similarly, the lower organic and nutrient content of stormwater runoff limits both the effectiveness of conventional biological treatment processes and land application disposal options. Several treatment and handling approaches are discussed and evaluated, including both centralized and satellite options. In addition, the primary and secondary economic (e.g. cost, land requirements) and environmental (e.g. air and water pollution, public health, etc.) impacts of stormwater runoff residuals treatment, handling, and disposal are reviewed.     

间接电合成对甲基苯甲醛减废工艺

采用间接电合成法生产对甲基苯甲醛,不仅产品的产率高,而且由于实现了电解媒质的循环使用,使整个过程无废液排放,既节省了资源,又保证了环境。该法以对二甲苯为原料,其反应过程为：Ｍｎ（Ⅱ）电解氧化生成Ｍｎ（Ⅲ）;Ｍｎ（Ⅲ）氧化对二甲苯生成对甲基苯甲醛。上述反应,前者的电流效率较高,为８５％左右;后者的产品产率较高,约为６９％。     

An Updated Cost Study for Enhanced Sludge Washing of Radioactive Waste

This article updates previous cost savings studies conducted to evaluate the use of enhanced sludge washing (ESW) of high‐level radioactive waste at the United States Department of Energy Hanford Site. The cost savings estimate was updated using stochastic analysis based on new information from the Independent Review of Hanford High Level Waste Volume and the more recent Tank Waste Remediation System Operation and Utilization Plan. It is estimated that implementation of ESW in the tank waste remediation system (TWRS) at the Hanford Site can save approximately $4.8 billion compared to the use of an alternative, simpler water wash. The simpler water wash dissolution was found to be 85 percent as effective as the ESW dissolution. Further, the updated remediation cost estimate of $4.8 billion savings is uncertain only within ±$1.6 billion at the 95 percent confidence interval. © 2002 Wiley Periodicals, Inc.