Membrane bioreactor technology: A novel approach to the treatment of compost leachate

Compost leachate forms during the composting process of organic material. It is rich in oxidizable organics, ammonia and metals, which pose a risk to the environment if released without proper treatment. An innovative method based on the membrane bioreactor (MBR) technology was developed to treat compost leachate over 39 days. Water quality parameters, such as pH, dissolved oxygen, ammonia, nitrate, nitrite and chemical oxygen demand (COD) were measured daily. Concentrations of caffeine and metals were measured over the course of the experiment using gas chromatography – mass spectrometry (GC/MS) and inductively coupled plasma – mass spectrometry (ICP–MS) respectively. A decrease of more than 99% was achieved for a COD of 116 g/L in the initial leachate. Ammonia was decreased from 2720 mg/L to 0.046 mg/L, while the nitrate concentration in the effluent rose to 710 mg/L. The bacteria in the MBR system adjusted to the presence of the leachate, and increased 4 orders of magnitude. Heavy metals were removed by at least 82.7% except copper. These successful results demonstrated the membrane bioreactor technology is feasible, efficient method for the treatment of compost leachate.     

水体中阿特拉津去除技术研究进展

在阐述了阿特拉津的污染现状和危害基础上,探讨了国内外常规生物处理技术及深度处理:膜处理、高级氧化、催化还原、吸附等技术对阿特拉津的去除研究进展,并总结对比了各种处理技术的优缺点。     

Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation

A submerged internal circulating membrane coagulation reactor(MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride(PACl) was used as coagulant,and a hydrophilic polyvinylidene fluoride(PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure(TMP), zeta potential(ZP) of the suspended particles in raw water, and KMnO_4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China(GB 5749-2006), as evaluated by turbidity(1 NTU) and total organic carbon(TOC)(5 mg/L)measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon(DOC) in the raw water also increased with increasing TMP in the range of 0.01–0.05 MPa. High ZP induced by PACl, such as 5–9 mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity.However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1–2 mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO_4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes.     

旋转接头在MBR反应器改良中的应用研究

随着MBR反应器在国内污水处理行业中的不断应用,其重要性进一步得到了业界的认可。但是,如何消减运行过程中的膜污染问题,成为制约MBR推广和应用的重要因素。文章通过实验,将旋转接头应用在MBR反应器的改良中,重点研究通过旋转接头实现膜组件的旋转运行模式对膜污染的抑制效果。     

膜分离技术处理高浓度味精废水试验研究

利用膜分离技术，将高浓度味精废水分离为数量不等的滤过水和浓缩水，浓缩水可再次开发利用，滤过水可直接进行生化处理，使外排废水达到国家规定标准。     

Adsorption and membrane separation for removal and recovery of volatile organic compounds

Volatile organic compounds(VOCs) are a crucial kind of pollutants in the environment due to their obvious features of severe toxicity, high volatility, and poor degradability. It is particularly urgent to control the emission of VOCs due to the persistent increase of concentration and the stringent regulations. In China, clear directions and requirements for reduction of VOCs have been given in the “national plan on environmental improvement for the 13th Five-Year Plan period”. Therefore, the de...     

Membrane fouling reduction through electrochemically regulating flocs aggregation in an electro-coagulation membrane reactor

Coupling coagulation and applied electric field is an efficient method to regulate cake layer porosity and hydrophilicity for alleviating ultrafiltration membrane (UF) fouling. However, the Al/Fe flocs aggregation behavior are induced from electric field and determine the cake layer structure, which has not been studied comparatively yet. Herein, the anti-fouling performance in an efficient electro-coagulation membrane reactor (ECMR, in which UF membrane modules are placed between electrodes) was investigated with Al/Fe anode and various electrochemical parameters from the viewpoint of regulating flocs aggregation. Both the cake layers formed from Al and Fe flocs under an electric field were more porous and hydrophilic in comparison with that formed without electric fields, resulting in an enhanced water flux under higher electric field strength. Comparing with Fe flocs, Al flocs had a faster growth rate and larger size, facilitating membrane pore block resistant, which was more pronounced in a higher current density. Furthermore, the cake layer formed from Al flocs was more porous than that formed from Fe flocs. Therefore, the anti-fouling performance of ECMR with Al anode was superior to that of ECMR with Fe anode. When the electric field strength increased from 0 to 10?V/cm, the normalized specific flux was improved from 71.2% to 89.4% for ECMR (Al) and from 48.1% to 70.1% for ECMR (Fe) at 30?min.     

Core activated sludge communities are influenced little by immigration: Case study of a membrane bioreactor plant

Microbial immigrants arriving with influent wastewater may influence activated sludge (AS) ecosystems. However, the extent to which immigration impacts AS communities is still debated. To explore the intensity of immigration impact, we used sequencing technology to track the raw wastewater and AS communities from a membrane bioreactor plant over a 12-month period. We first distinguished core populations from peripheral ones in both raw wastewater and AS based on their occurrence frequency and abundance. The results showed that core OTUs (≥ 80% occurrence frequency) made up a large fraction (> 90%) of total sequences, while peripheral OTUs composed the majority of all detected OTUs but merely occupied a few sequences. A significant difference in core communities between the influent and AS was found, as well as between the compositions of core and peripheral populations. Additionally, the persistent functional bacteria of AS, although not numerically dominant, accounted for 96.24% of the total sequences related to nutrient turnover, suggesting the presence of a small number of longstanding and core functional bacteria in the AS ecosystem. Importantly, 64% of the 5188 OTUs in AS, which accounted for 91.51% of the sequences, exhibited positive growth rates, which suggested that their apparent abundances were due to growth within the plant, not from immigration. Taken together, these results demonstrated that the impact of influent populations on core AS communities was limited. Overall, this work provides quantitative insights into the impact of immigration, which is expected to advance our understanding of the AS community assembly.     

含盐废水电渗析膜分离处理工艺研究

在水资源日益紧张、含盐废水排放量日益增多的大趋势下,寻求经济有效的含盐废水处理技术已成为重要的研究课题。以厦门某食品企业水产品加工腌泡环节含盐废水为研究对象。含盐废水经氨水沉淀、离子交换树脂软化处理,废水中钙镁离子被有效脱除,出水钙镁质量浓度已经降为10．4mg·L-1,达到软水水质标准。软化后的废水经4‰聚丙烯酰胺（PAM）絮凝并通过活性炭吸附,污染密度指数值（SDI）降低至0．41,完全达到膜分离装置进水水质的要求。预处理液再经电渗析膜进一步浓缩分离后,氯化钠质量浓度可由7351mg·L-1提升到78156mg·L-1,对盐分浓缩了10倍以上,达到废水和盐分的处理回收利用。本处理工艺流程简洁,药耗少、能耗低,比较适合小规模含盐废水的综合处理。     

Optimization of mixture ratio of electrolyte for reducing activation resistance of proton exchange membrane fuel cell

The purpose of this study is to find an optimal mixture ratio of the platinum-loaded carbon catalyst and the electrolyte in a membrane electrode assembly (MEA) of a proton exchange membrane fuel cell for reducing the activation resistance, which influences the electrochemical surface area, activation polarization, and maximum power density of the MEA. First, mixture ratios of 10, 20, 40, and 60 wt% platinum-loaded carbon catalysts and electrolyte were examined. The results indicated that the fuel cell performance improved for mixing weight ratios of 1.0:2.0 in 10 wt% Pt/C, 1.0:1.8 in 20 wt% Pt/C, 1.0:1.1 in 40 wt% Pt/C, and 1.0:0.5 in 60 wt% Pt/C. Next, we evaluated the activation resistances of the MEA from the AC impedance characteristics using the optimal mixing weight ratio of the platinum-loaded carbon catalyst and the electrolyte. It was found that the activation resistances of the anode and cathode decrease with an increase in the weight ratio of platinum-loaded carbon in the catalyst layer.