Advanced Materials Research Vols. 518-523

Abstract: Vermicomposting experiments were conducted to study the effects of Chinese medicine residue at optimal moisture content on growth and fecundity of Eisenia foetida in laboratory. Under the conditions of different pH and inoculation density, the treatment effects were determined through analyzing the changes of Chinese medicine residue properties. The results showed that the optimal pH for Eisenia foetida was 6.5, and that 40 earthworms per 1kg residues was the most appropriate density for unfermented Chinese medicine residue. Compared with the control, the earthworm treatment could significantly accelerate organic matter mineralization and promote the degradation of materials. After vermicomposting, pH value of the residue was close to neutral, and total N and the enzyme activities were both significantly increased. While the value of C/N and TOC were both reduced. These results suggested that vermicomposting was a better way for Chinese medicine residue treatment, the rate of quantitative reduction and the treatment efficiency were 73.54% and 44.52%, respectively.

Abstract: As a concomitant of wastewater biological treatment, waste activated sludge (WAS) has become a current problem due to its huge production and potential environmental pollution. In this paper, the WAS from municipal wastewater treatment plant (WWTP) treated by the cation exchange resin (CER) method for microbial flocculant (MBF) preparation was introduced. Various influencing factors, including sludge pH, sludge concentration, CER dosage, stirring intensity, and treatment time, were systematically investigated. The MBF extracted from neutral or alkalescent sludge shows higher flocculating activity than that from acid sludge. Increasing sludge concentration is beneficial to the MBF extraction. The flocculating activity of the extracted MBF can be enhanced by increasing the stirring intensity or the added CER dose. However, with extending extraction time, the flocculating activity of the extracted MBF increases and reaches to a peak, and then hold the line on the whole. Therefore, the CER method is feasible to extract MBF from excess sludge, which could provide a new way for WAS resource reuse, as well as cut down the cost of MBF preparation.

Abstract: In this paper, a small medical waste pyrolysis furnance, which could disposal 1t wastes, is designed for the safe disposal of medical wastes, by in-depth research of pyrolysis, detailed calculation analysis, and considering the experimental results and other factors in general. The flue gas treatment system of the small medical waste pyrolysis furnance is designed applying 3T principle, and the dioxin’s later synthesis is controlled, so the dioxin emissions problem is also resolved. The results show that the small furnance has reasonable configuration, works reliably, and it could self-support freely, its emissions meet the national standards for the dioxin emissions 0.213 ng/m³.

Abstract: Uncontrolled growth of the population in recent years has made the huge amount of domestic waste engaged. In order to provide information for setting up a proper system to sort and recycle waste, we conducted a survey of evaluating residential knowledge and attitudes. An anonymous questionnaire was used among 523 residents including 237 males and 286 females. Their awareness of waste sorting, habit of dealing with waste and willingness of participating recycling activities were asked. The results showed that awareness on sorting and recycling among residents was not sufficient. But most of them have a strong willing to learn pertinent knowledge and participate recycling activities. Concerning the habit of dealing with waste, 48.5% of them answered they always threw them in the garbage directly. It suggested that owning to sorting and recycling at generation point the residents’ awareness need to be enhanced.

Abstract: In this paper, two fly ash samples from a popular of circulating fluidized bed (CFB) incinerators operated in spring and winter were detected. The organic pollutants of PAHs and Dioxins were 8.647 mg/kg and 778.859 pgI-TEQ/g respectively for the sample in spring, 11.008 mg/kg and 888.318 pgI-TEQ/g for the sample in winter. The distribution of Dioxins was analyzed, 2,3,4,7,8-PeCDF,2,3,7,8-TCDF and 2,3,7,8-TCDD were found to gave the great contribution to the total I-TEQ.

Abstract: Evaluation index system of reverse logistics partners is designed from four aspects: cost, environment performance and basic factors of an enterprise, combined with features of automobile manufacturing enterprises. Meanwhile, weight of indexes is derived from an integrated method, and TOPSIS method is adopted for evaluation. An example is given to show the feasibility of the method in selection of reverse logistics partners for automobile manufacturing enterprises.

Abstract: An enormous amount of municipal solid waste (MSW) has increasingly become a threat for many cities around the world. As an effective method of waste disposal, source separation program of MSW is concerned by more and more researchers across disciplines with other waste management options for the purpose of abating degradation in urban environment. The purpose of this article is to present the achievements of theoretical and empirical studies in the field of source-separation programs around the world in recent years, which may provide a new insight of environmental problems into decision making of governments and citizens.

Abstract: The current recycling networks of the waste electronic products in China are analyzed from the view of the layout of the recycling center and the structure of recycling channel. The optimization model of an e-waste recycling network is established according to our national actual condition, and solved with simulated data. The results show that setting up detecting centers dispersedly can reduce the transportation amount of the waste electronic products and reduce transportation costs, and the relative concentration of recycling processing center can achieve economies of scale and lower the total cost.

Abstract: The dry crushing of wasted printed circuit boards (PCBs) can make secondary contamination. In this paper, a wet comminution process is put forward to solve the difficulties. For the comminution product, the distributions of particle size, liberation degree and metal grade are analyzed, and for the product below 1mm, a wet metal beneficiation process combined with shaking table and flotation is employed. The results show that the Whole PCBs could be comminuted by the MX wet impact crusher, and the cumulative yield, liberation degree, total metal content and its copper grade of the product below 1mm is 83.49%, 97%, 83.46% and 20.50%respectively, and that metal concentrates could be beneficiated by XZY wet shaking table, and the yield, total metal weight, copper grade of the metal concentrate, the recovery of total metal and copper is 34.87%, 88.99%, 50.73%,79.90% and 78.07% respectively keeping the feeding concentration at 20% and water consumption in 1100L/h. For these metals included by shaking-table middling, the separation of both flotation and shaking table is carried out, and the total metal content and its copper grade, recovery in metal concentrate 2′ is 72.07% , 31.59% and62.04% respectively, meanwhile the copper grade of tailings in flotation and shaking table are decreased to 1.26% and 2.94%. The wet treatment process can effectively concentrate these valuable metals from waste PCBs.

Abstract: The recycle and reuse of waste filter bags will be a important research direction for renewable resource. A huge quantity can be seen in the waste bag filters with the more widely used of the bag type dust collector, Therefore, it has become an urgent issue to seek a comprehensive utilization method for waste bag filters. This article analyses the domestic market situation of filter bags and causes of waste bags and the treatment and disposal of the waste filter bag. The recycling methods and approaches of the relevant problems in the waste bag disposal has been described, the result shows a positive study on rational and effective measures for the treatment and disposal of waste filter bag has a very important significance.