摇动床生物膜反应器处理生活污水

介绍了一种新型的生物膜反应器——摇动床反应器,并采用模拟生活污水进行了小试试验研究。试验结果表明,在HRT=6h,DO=3～4mg/L,T=20～25℃,pH=7～8,C/N=20的条件下,该工艺可以达到最佳运行状况,有机负荷为0.64～3.00kgCOD/(m3.d)下,COD去除率平均达到85%,出水TN≤10mg/L,达到国家一级排放标准。     

An advanced study on the hydrometallurgical processing of waste computer printed circuit boards to extract their valuable content of metals

This study refers to two chemical leaching systems for the base and precious metals extraction from waste printed circuit boards (WPCBs); sulfuric acid with hydrogen peroxide have been used for the first group of metals, meantime thiourea with the ferric ion in sulfuric acid medium were employed for the second one. The cementation process with zinc, copper and iron metal powders was attempted for solutions purification. The effects of hydrogen peroxide volume in rapport with sulfuric acid concentration and temperature were evaluated for oxidative leaching process. 2 M H₂SO₄ (98% w/v), 5% H₂O_2, 25 °C, 1/10 S/L ratio and 200 rpm were founded as optimal conditions for Cu extraction. Thiourea acid leaching process, performed on the solid filtrate obtained after three oxidative leaching steps, was carried out with 20 g/L of CS(NH₂)₂, 6 g/L of Fe³⁺, 0.5 M H₂SO₄, The cross-leaching method was applied by reusing of thiourea liquid suspension and immersing 5 g/L of this reagent for each other experiment material of leaching. This procedure has lead to the doubling and, respectively, tripling, of gold and silver concentrations into solution. These results reveal a very efficient, promising and environmental friendly method for WPCBs processing.     

Sociological survey in a municipality with a high level separate collection programme in an area of historic unpopularity

Behaviours, opinions and knowledge of citizens on MSW and separate collection were investigated in the city of Mercato San Severino (about 22,000 people), in the Campania region of Southern Italy that is an area suffering from a serious solid waste emergency that has lasted over 17 years due to the absence of treatment facilities. The image of heaps of rubbish in the streets of Naples and other nearby cities is only one side of the coin. Mercato San Severino has adopted an effective kerbside collection system since 2001 and a pay-as-you-throw program during 2005, guaranteeing more than the minimum level of recycling required by the Italian legislation. Structured questionnaires were administered to a sample of 500 people in 2010. Chi-square tests of independence were applied to state whether the differences were statistically significant (5%). About 90% of the sample stated that the success of the separate collection program was due to either the citizens and local authority or only the local authority, highlighting the leading role of the local authority and confirming that trust is the key to any social program success. The registered level of knowledge was better than that of nearby university students and citizens. The higher the education level, the greater the level of knowledge was.     

An assessment on the recycling opportunities of wastes emanating from scrap metal processing in Mauritius

This paper presents an assessment on the wastes namely slag, dust, mill scale and sludge resulting from scrap metal processing. The aim of this study is to demonstrate that there are various ways via which scrap metal processing wastes can be reused or recycled in other applications instead of simply diverting them to the landfill. These wastes are briefly described and an overview on the different areas of applications is presented. Based on the results obtained, the waste generation factor developed was 349.3 kg per ton of steel produced and it was reported that slag represents 72% of the total wastes emanating from the iron and steel industry in Mauritius. Finally the suitability of the different treatment and valorisation options in the context of Mauritius is examined.     

Economies of size and density in municipal solid waste recycling in Portugal

The recycling of municipal solid waste has a remarkable importance in the preservation of the environment and the welfare of the society. However, it is also important that this service can be provided with efficient costs. This paper aims to search for economies of output density and economies of size in the selective collection and recycling activities in Portugal and to identify the size the utilities should have to become more cost efficient. The sample comprises all Portuguese recycling utilities operating in the wholesale segment in the period 2006–2010. The results show that the Portuguese recycling utilities should increase the quantities of municipal solid waste for recycling (especially glass and paper) and also become larger to dimensions corresponding to a supply of 400–550 thousand inhabitants. With the increasing amount of glass collected, utilities are simultaneously struggling to fulfill the targets established by the European legislation and explore the existing economies of output density. The results also show that the management of these services carried out by private companies and the use of incineration (by utilities) seem to reduce the costs of utilities while the regulation of these services and the composting of waste held by utilities tend to increase costs.     

Kinetic analysis of transesterification of waste pig fat in supercritical alcohols

The kinetic analysis method using non-isothermal technique was proposed to determine the kinetic parameters for the transesterification reaction of waste pig fat in supercritical alcohols. To investigate the transesterification of waste pig fat, the waste pig fat to alcohol ratio (w/w) was varied from 1:1.5 to 1:2.5 between the temperatures 220 and 290 °C at an interval of 10 °C in a 25 mL batch reactor. The products were analyzed by gas chromatography mass spectrometry. To verify the effectiveness of the proposed kinetic analysis method, the experimental values were compared with the values calculated using the kinetic parameters obtained from this work. It was found that the proposed kinetic analysis method gave reliable kinetic parameters for the transesterification of waste pig fat in supercritical alcohols. Further, it was found that the apparent activation energy for supercritical ethanol was lower than the value for supercritical methanol.     

A new strain for recovering precious metals from waste printed circuit boards

A new strain, Pseudomonas Chlororaphis (PC), was found for dissolving gold, silver, and copper from the metallic particles of crushed waste printed circuit boards (PCBs). The optimized conditions that greatly improved the ability of producing CN^? (for dissolving metals) were obtained. Dissolving experiments of pure gold, silver, and copper showed that the metals could be changed into Au⁺, Ag⁺, and Cu²⁺. PC cells and their secreta would adsorb metallic ions. Meanwhile, metallic ions destroyed the growth of PC. Dissolving experiments of metallic particles from crushed waste PCBs were performed by PC. The results indicated that 8.2% of the gold, 12.1% silver, and 52.3% copper were dissolved into solution. This paper contributed significance information to recovering precious metals from waste PCBs by bioleaching.     

Process analysis of an industrial waste-to-energy plant: Theory and experiments

Thermal conversion is fundamental in an integrated waste management system due to the capability of reducing mass and volume of waste and recovering energy content from unrecyclable materials. Indeed, power generation from industrial solid wastes (ISW) is a topic of great interest for its appeal in the field of renewable energy production as well as for an increasing public concern related to its emissions. This paper is based on the process engineering and optimization analysis, commissioned to the University Campus-Biomedico of Rome by the MIDA Tecnologie Ambientali S.r.l. enterprise, ended up in the construction of an ISW thermo-conversion plant in Crotone (Southern Italy), where it is nowadays operating. The scientific approach to the process analysis is founded on a novel cascade numerical simulation of each plant section and it has been used initially in the process design step and after to simulate the performances of the industrial plant. In this paper, the plant process scheme is described together with the values of main operating parameters monitored during the experimental test runs. The thermodynamic and kinetic basics of the mathematical model for the simulation of the energy recovery and flue gas treatment sections are presented. Moreover, the simulation results, together with the implemented parameters, are given and compared to the experimental data for 10 specific plant test runs. It was found that the model is capable to predict the process performances in the energy production as well as in the gas treatment sections with high accuracy by knowing a set of measurable input variables. In the paper fundamental plant variables have been considered such as steam temperature, steam flow rate, power generated as well as temperature, flow rate and composition of the resulting flue gas; therefore, the mathematical model can be simply implemented as a reliable and efficient tool for management optimization of this kind of plants.     

物联网技术在城市生活垃圾收运系统中的应用

我国的城市生活垃圾收运系统因其回收率低,监管难等问题,一直受到社会的广泛关注,而物联网技术因其可追溯性、动态性等特点,在解决该问题上表现出其显著优势。简要介绍了物联网技术的作用及其应用领域,总结了国内外基于物联网技术的城市生活垃圾收运情况,以我国上海市餐厨垃圾收运情况为案例,对其现状和目前存在的问题进行了总结,并结合物联网技术对餐厨垃圾信息化收运的管理方法进行了展望。     

东三省“十二五”城镇污水厂投资与减排效益分析

东北三省"十二五"主要水污染物减排项目方案实施后,必然会引起环境发生一定变化,环境效益正是污染减排工程的环境后果的代表。利用西方经济学中的边际效用理论对"十二五"期间东三省城镇污水处理厂单位投资的COD削减量进行分析。依据投入的环境边际效益对各省工作重点提出建议。