Role of rural solid waste management in non-point source pollution control of Dianchi Lake catchments, China

In recent years, with control of the main municipal and industrial point pollution sources and implementation of cleaning for some inner pollution sources in the water body, the discharge of point source pollution decreased gradually, while non-point source pollution has become increasingly distressing in Dianchi Lake catchments. As one of the major targets in non-point source pollution control, an integrated solid waste controlling strategy combined with a technological solution and management system was proposed and implemented based on the waste disposal situation and characteristics of rural solid waste in the demonstration area. As the key technology in rural solid waste treatment, both centralized plant-scale composting and a dispersed farmer-operated waste treating system showed promise in rendering timely benefits in efficiency, large handling capacity, high quality of the end product, as well as good economic return. Problems encountered during multi-substrates co-composting such as pathogens, high moisture content, asynchronism in the decomposition of different substrates, and low quality of the end product can all be tackled. 92.5% of solid waste was collected in the demonstration area, while the treating and recycling ratio reached 87.9%, which prevented 32.2 t nitrogen and 3.9 t phosphorus per year from entering the water body of Dianchi Lake after implementation of the project.     

我国城市垃圾现状与可持续发展研究

首先分析我国城市垃圾问题的现状,介绍了我国目前城市垃圾处理技术,并对城市可持续发展垃圾治理问题进行了探讨。     

中小城市生活垃圾处理方法研讨

根据对城市生活垃圾不同的处理方法,并结合城市生活垃圾的成分,提出了中小城市应按其实际情况采用适宣本地的生活垃圾无害化处理的相应方法。     

A new approach to assessment and management of the impact from medical liquid radioactive waste

The Swedish regulations concerning disposal of clinical radioactive waste are currently under revision and a graded approach is proposed for risk limitation purposes. To assist the revision procedures, a screening study was performed to estimate public exposures from liquid releases from hospitals to public sewers. The results showed that doses to sewage workers were above the dose constraint of 100muSva(-1) especially for (131)I and (99m)Tc. Hence, a dynamic model, LUCIA, was developed for realistic assessments in which radionuclide transportation in sewers was modelled. Probabilistic simulations were performed to obtain probability distributions of radionuclide concentrations in sludge. Concurrently, estimates of the effective doses to sewage workers decreased significantly and were below 10muSva(-1) except for (111)In and (131)I. However, the Kd-coefficients representing the partition of radioactivity between water and sludge in sewers are highly uncertain for (111)In. As shown by sensitivity studies, these values are the major determinant of the exposures in sewers.     

Current Status of Manufacturing Hazardous Waste in Shanghai

Abstract

It is difficult to manage the manufacturing hazardous waste (MHW) which is generated from a huge amount of complicated sources and causes very serious pollution. Therefore more and more attention has been paid to MHW pollution. Shanghai, as an industrial and economic center and an international metropolis in China, has a vast industrial system spanning a multitude of sectors, which generates MHW not only in a huge magnitude but also in a large variety of types from complicated sources, resulting in severe pollution. In 2003, the production of MHW in Shanghai is about 3.96 × 10⁵ ton, involving 33 indices. Most of MHW in Shanghai is treated and disposed of, but a significant portion is not handled properly and effectively. This paper carries out in-field investigation on the current status of MHW production and treatment in Shanghai, and puts forward scientific proposals that Shanghai should facilitate cleaner production and minimize hazardous waste; strictly enforce hazardous waste registration system, strengthen monitoring the certified enterprises; strengthen intent disposal center construction and realize hazardous waste reclamation; accelerate establishing the technical criteria and the management policy, promote the research and development on the treatment and disposal technology, and strengthen information management, thus realizing integrated management on MHW pollution.     

A choice experiment analysis for solid waste disposal option: a case study in Malaysia

In Malaysia, most municipal wastes currently are disposed into poorly managed 'controlled tipping' systems with little or no pollution protection measures. This study was undertaken to assist the relevant governmental bodies and service providers to identify an improved waste disposal management strategy. The study applied the choice experiment technique to estimate the nonmarket values for a number of waste disposal technologies. Implicit prices for environmental attributes such as psychological fear, land use, air pollution, and river water quality were estimated. Compensating surplus estimates incorporating distance from the residences of the respondents to the proposed disposal facility were calculated for a number of generic and technology-specific choice sets. The resulting estimates were higher for technology-specific options, and the distance factor was a significant determinant in setting an equitable solid waste management fee.     

Valorization of solid waste in sugar factories with possible applications in India : A review

Sugar production is a major agro-based industry in India that generates various solid wastes viz. sugarcane trash, bagasse, press mud and bagasse fly ash. This work examines the state-of-the-art in innovative value added products that can be obtained from the transformation of these wastes. Challenges in implementing these waste valorization solutions are also highlighted. It is observed that the extent of research and adoption of these solutions vary considerably. Both industry involvement as well as government encouragement is required in translating the research findings into commercial products.     

Optimization of the recovery of plastics for recycling by density media separation cyclones

Material recovery processes are presented as the optimum option for recycling plastic wastes as a means of recovering hydrocarbon resources. There exist a large variety of automated material recovery processes for recycling of such wastes but each with significant limitations. Of these, the separation based on differences in densities is advocated as the optimum process either for producing recycled products or preparing wastes for subsequent recovery processing.Density separation processes based on cyclone type density media separation (DMS) is presented as an important, potential method for increasing plastics recycling process capacities. It is demonstrated to have the capacity to separate a significantly larger range of particle sizes than those presently processed industrially. The mathematical relationship for the prediction of quality of typical LARCODEMS type density media separations by particle size and density as expressed by the Ecart Probable is presented.A proposed device configuration is presented for density media separation to optimize the recovery and purity of both density fractions produced. It is also suggested that to be economically viable, a large scale of operation is required for industrial plastics recycling operations recovering and producing a number of different plastics with a purity to be used as a substitute for virgin material.     

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.     

Combination of ion exchange system and biological reactors for simultaneous removal of ammonia and organics

A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH₄⁺ could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m²?s of a maximum flux. On the other hand, the removal of NO₃⁻ was 3.5 times faster than NH₄⁺ and the maximum flux was calculated to be 3.4 mg N/m²?s. The systems for NH₄⁺ and NO₃⁻ removal were combined for establishing the IEBR process. When the process was operated in a continuous mode, approximately 95.8% of NH₄⁺ was removed showing an average flux of 0.22 mg N/m²·s. The removal efficiency of total nitrogen was calculated as 94.5% whereas that of organics was 99.5%. It was concluded that the IEBR process would be effectively used for a simultaneous removal of NH₄⁺ and organics.