固体停留时间对HLB-MR反应器直接回收城市污水中有机物的影响

为优化高负荷生物絮凝-膜反应器（HLB-MR）的工艺参数,提高其资源化城市污水的效能,采用平行对比实验,考察了不同固体停留时间（t_SR）条件下反应器的有机物去除效率、生物絮凝效果、有机物回收效果和膜污染情况。结果表明：在t_SR分别为0.2、0.6、1.0 d时,HLB-MR反应器有机物去除效率均在85%以上,其出水化学需氧量（COD）质量浓度均保持在30 mg/L左右;反应器内的生物絮凝效果随着t_SR的延长而增强,其胶体COD絮凝效率从t_SR为0.2 d时的66%增加到t_SR为1.0 d时的95%,与此同时,有机物的矿化损失率也逐渐增加,从t_SR为0.2 d时的6.9%增加到t_SR为1.0 d时的10.5%,总COD的回收率逐渐降低;反应器内浓缩液的膜污染潜势随着t_SR的延长逐渐缓解,这与较长t_SR条件下反应器内胞外聚合物（EPS）产量较高、生物絮凝效果较好、微细颗粒（0~1 μm）的颗粒浓度较低有关。经过综合对比分析,0.6 d为反应器较优的t_SR参数,在该条件下,胶体COD的絮凝效率高达90%,膜污染程度较轻;总COD的矿化损失率低至7.4%,总COD的回收率（忽略膜清洗时有机物损失）可高达80%以上。     

Degradation of Coking Wastewater under Microwave Irradiation in the Presence of Modified Activated Carbon

In this study, a new material consisting of activated‐carbon‐containing magnetic oxide is prepared for assisted microwave (MW) irradiation treatment of coking wastewater. The optimum condition for degrading coking wastewater is 98.14% chemical oxygen demand (COD), under which 87.57% ammonia nitrogen (NH₃–N) can be removed. The results are verified by GC–MS, showing that most organic pollutants can be adsorbed by modified activated carbon (MAC). The surface morphology and elemental composition of MAC before and after microwave irradiation and adsorption is determined by scanning electron microscopy. After microwave irradiation, many apertures of pores looked relatively large. It can be shown that MAC as a catalyst in the microwave‐assisted treatment process has many advantages, including rapid degradation of COD and NH₃–N. In conclusion, microwave‐irradiation‐assisted MAC treatment of coking wastewater is a novel technology that is economical, efficient, and has broad prospects for development.     

Removal of Selected Micropollutants from Synthetic Wastewater by Electrooxidation Using Oxidized Titanium and Graphite Electrodes

Micropollutants cover a variety of compounds that mainly originate from the pharmaceutical and agricultural sectors. Even at trace concentrations, the discharge of micropollutants into water bodies pose a serious threat to the environment and human health. Their removal from wastewaters at treatment plants before their discharge into the environment has become one of the leading topics of research. Physical, chemical, and biological treatment methods have been listed in the literature for efficient removal of a variety of pollutants. In this study, seven micropollutants, namely 4‐tert‐octylphenol, atrazine, 2,4,6‐trichlorophenol, fluoxetine, estrone, penconazole, and di‐n‐octyl phthalate, are spiked into municipal simulated synthetic wastewater and treated by a laboratory‐scale electrooxidation (EO) system using oxidized titanium and graphite electrode as anode and cathode, respectively. Sensitive determination of the selected micropollutants by gas chromatography–mass spectrometry (GC‐MS) before and after treatment is performed after their pre‐concentration using an eco‐friendly switchable solvent liquid‐phase microextraction method (SSLPME). The pH value, applied current, and reaction period are optimized to enhance the removal efficiency of micropollutants. Results show that the highest removal efficiency of all micropollutants is obtained at pH 3, 20 min reaction period, and 3 A applied current. The operational costs are also investigated in this study.     

Supported TiO2 on Kaolin,Cordierite, and Calcite for Photocatalytic Removal of Dyes from Wastewater

Kaolin, cordierite, and calcite are investigated as supports for TiO₂. The prepared TiO₂/support samples are examined for the removal of organic dyes from wastewater. The samples are preliminarily investigated to identify the optimal loaded system using synthetic wastewater containing methylene blue (MB). Data indicate that the investigated support significantly affects the photocatalytic activity of the supported TiO₂. Low photocatalytic activity toward MB degradation is observed upon using TiO₂/calcite when compared to the unsupported TiO₂. Interaction between calcite and titania species probably occurrs to produce the less photoactive CaTiO₃ amorphous species. Anatase TiO₂ is obtained upon using kaolin and cordierite as supports. The low photocatalytic performance of the TiO₂/kaolin sample is also observed. A high concentration of MB on TiO₂/kaolin surfaces blocks the photoactive sites. TiO₂/cordierite shows the highest photocatalytic activity compared to the unsupported TiO₂ as well as the other TiO₂/support samples. Rigid cordierite particles suppress the agglomeration of TiO₂ particles during the preparation, leading to a high exposed surface of TiO₂ towards light illumination. TiO₂/cordierite is investigated for the removal of organic dye from real wastewater collected from a textile dyeing factory. Color removal of up to 46% is achieved upon UV irradiation.     

Algal Cultivation for Treating Wastewater in African Developing Countries: A Review

The tremendous increase in human population and rapid decline in freshwater resources have necessitated the development of innovative and sustainable wastewater treatment methods. Africa as a developing continent is currently backing on sustainable solutions to tackle impending water resource crisis brought forward by wastewater‐induced environmental pollution and climate change. Microalgae‐based wastewater treatment systems represent an emerging technology that is capable of meeting the new demand for improved wastewater treatment and climate change mitigation strategies in an environmentally friendly manner. This review critically looks at the opportunities of Africa in harnessing and exploiting the potential of microalgae for the treatment of various wastewaters based on their capacity to recycle nutrients and for concurrent production of valuable biomass and several useful metabolites. Wastewaters, if improperly/completely untreated and discharged, simultaneously pollute freshwater sources and present significant health and environmental risks. Nutrients in wastewater can be utilized and recovered in the form of marketable biomass and products when integrated with the cultivation of microalgae. Several valuable bioproducts can be generated from wastewater‐grown microalgal biomass including biofuels, biofertilizers, animal feed, and various bioactive compounds. This biorefinery approach would most certainly improve wastewater treatment process economics, enhancing the technical feasibility of algae‐based wastewater remediation in African countries.     

Spinel Ferrite Mediated Photo‐Fenton Degradation of Phenolic Analogues: A Detailed Study Employing Two Distinct Inorganic Oxidants

The present work demonstrates the applicability of ferrites as photo‐Fenton catalysts for deterioration of different phenolic derivatives. To analyze optimal reaction conditions, experiments are performed with four magnetic spinel ferrites MFe₂O₄ (M = Co, Cu, Ni, and Zn) and two inorganic oxidants, i.e., hydrogen peroxide (HP) and potassium peroxymonosulfate (PMS). The reactions are performed using p‐nitrophenol as phenolic probe. CuFe₂O₄ and CoFe₂O₄ possessed excellent ability to activate HP and PMS, respectively, among all four synthesized catalysts. A noteworthy aspect of two oxidizing agents is that the concentration of PMS used during the reaction is four times less than HP. Further, the broad pH activity of PMS provides a significant advantage over HP. The optimal reaction conditions, when HP is the oxidant in the photo‐Fenton degradation, are 0.50 g L^?1 MFe₂O₄, pH 2.5, and 8.8 mM HP. Although PMS is active in a wide pH range (2–10), adequate reaction conditions are 0.50 g L^?1 MFe₂O₄, natural pH, and 2.2 mM PMS. The photo‐Fenton activity of ferrites is extended to the degradation of different nitro‐ and chloro‐analogs of phenol (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol, 2,4,6‐trinitrophenol, 2‐chlorophenol, 3‐chlorophenol, 4‐chlorophenol, 2,4‐dichlorophenol) with only two ferrites (CuFe₂O₄ and CoFe₂O₄). A comparative study is performed with the two oxidants (HP and PMS) with positive results. Finally, stability and reusability of magnetic ferrites as catalysts are also studied to prove their use in phenolic solution treatment.     

造纸废水灌溉对芦苇湿地微生物的影响研究

为了解造纸废水灌溉对滨海芦苇湿地的影响,测定了几种灌溉条件下湿地基质中微生物数量、微生物量碳/总有机碳(MBC/ TOC)和土壤有效硫等指标.结果表明:造纸废水灌溉能显著提高基质中微生物数量和活性,且受季节影响较明显,一般在9月份最高;微生物数量在基质内垂直分布为上层>下层,特别是放线菌、真菌;反硝化细菌与土壤TN,纤维素分解菌与废水COD去除率,及MBC/TOC与基质呼吸强度相关性较好;硫酸盐还原细菌数量在10月份以后激增,使基质变黑,但对芦苇根系影响较小.废水灌溉能改良滨海盐碱土壤,促进退化生态系统的修复,但不同灌溉模式对微生物种群组成的影响不同,推荐采用间歇灌溉(w4)或低水深恒流灌溉(w1)模式.     

Evaluation of a Novel Control Method on Biofilm Parameters in an Aerated Submerged Fixed‐bed Biofilm Reactor

One of the critical technological parameter in operation of aerated submerged fixed‐bed biofilm reactor (ASFBBR) is the control over process of biofilm detachment. Both, an excessive growth of biomass with its accumulation in the bioreactor and an exceeded biofilm detachment rate, cause serious operational and technological problems. The studies presented in this paper demonstrate that in an ASFBBR reactor with a PVC bed carrier media, an effective way to maintain a proper shear stress acting on the biofilm and causing its detachment could be an internal recirculation of wastewater instead of backwashing with wastewater or air flushing. In case of polishing of oil‐refinery wastewater with average COD loading rate equal to 9 g COD/(m² day), the minimum value of the hydraulic loading rate in such reactor is 1.9 m³/(m² h), at which there was no excessive growth of biofilms. Despite a significant decrease of the biofilms thickness and amount of biomass in the reactor, there was no significant decline in the efficiency of pollutant removal from oil‐refinery wastewater, which made it possible to obtain the quality of effluent at the outlet of the bioreactor significantly below the water permits and standards.     

Response Surface Analysis and Statistical Modeling of Sulfide Generation from Municipal Wastewater

In this study, the interactive effects of four independent variables (initial chemical oxygen demand (COD) concentration, rotational velocity, temperature, and retention time) on the sulfide generation process in municipal wastewater were investigated. The process was modeled and analyzed with the variables in a series batch experiments. Experiments were conducted based on a central composite face‐centered design and analyzed using response surface methodology. The region of exploration for the process was taken as the area enclosed by COD (250 and 650 mg/L), rotational velocity (40 and 200 rpm), temperature (16 and 28°C), and retention time (2 and 40 h) boundaries. Eleven dependent parameters were either directly measured or calculated as response. The most influential variable on H₂S (g) production was found to be retention time. The results showed that simultaneous increase in temperature and rotational velocity caused an increasing trend in the amount of H₂S (g) emitted. Total sulfide was decreased by increasing rotational velocity due to more H₂S (g) secretion resulting from increased mixing rate. The present study provides valuable information about interrelations of quality and process parameters at different values of the studied variables.