Removal of organic matter in freshwater sediment by microbial fuel cells at various external resistances

BACKGROUND: Besides acting as power sources, sediment microbial fuel cells (SMFC) could be explored to remove organic matter in sediments and then maintain the water quality in aquatic environments. Until now, the role of the external resistance in the removal of organic matter by SMFC has received only limited attention. In this work, the removal of organic matters in sediments by lab‐scale SMFCs at five different external resistances from 10 to 1000 Ω was investigated. RESLUTS: The external resistance in SMFCs had a strong influence on the working potentials of anodes. Application of a 100 Ω external resistance corresponded to the lowest internal resistance and highest removal efficiency of organic matter in sediment. The removal efficiency of readily oxidizable organic matter in a layer of sediment with a distance of 0–1 cm to the anode reached 28.3 ± 1.9% at 100 Ω external resistance after 2 months of operation. In addition, there existed a linear relationship between current production from the SMFCs and removal efficiency of organic matter from sediments. CONCLUSIONS: The performance of SMFCs for the removal of organic matter in sediments could be enhanced through the selection of optimal external resistance. The SMFC real‐time removal process could be monitored remotely using current generated. Thus, SMFCs offer an attractive alternative for the environmentally‐friendly removal of organic matter in sediments. Copyright © 2010 Society of Chemical Industry     

Ozone,Oxalic Acid,and Organic Matter Molecular Weight – Effects on Coagulation

Ozonation breaks long chain natural organic matter (NOM) into smaller, more oxygenated compounds such as oxalic acid. The purpose of this study was to evaluate the effects of such transformations on coagulation in high dissolved organic carbon synthetic waters with model particles. Results indicate that the presence of oxalic acid adversely affects the removal of turbidity and organic carbon by coagulation and filtration. The results also show that larger (higher molecular weight) organic matter is easier to remove by coagulation than lower molecular weight organic matter. In both cases, ozonation results in an increase in the optimum coagulant dose or a decrease in the amount of turbidity and TOC removal at a given coagulant dose.     

Desulfurization of a Turkish lignite at various gas atmospheres by pyrolysis. Effect of mineral matter

An investigation was made of the removal of pyritic and organic sulfur by pyrolysis at ambient pressure of a Turkish lignite under nitrogen and carbon dioxide atmospheres and the effect of mineral matter on the sulfur removal in pyrolysis of HCl and HCl/HF-treated coal under carbon dioxide atmosphere. Results obtained indicated that both pyritic and organic sulfur removal increased with increasing pyrolysis temperature. The pyrolysis in carbon dioxide atmosphere had more effect on the organic sulfur removal at high temperatures. As a consequence of treatment of coal with HCl, pyritic sulfur removal increased but organic sulfur removal decreased. This implies that the removal of carbonates from coal negatively affects the organic sulfur removal. The observed decrease in organic sulfur removal may be related to the decrease in pyrolytic conversion. It was observed that HCl/HF treatment has an increased effect on the pyritic removal and organic sulfur removal during pyrolysis. The increase in organic sulfur removal after HF-treatment therefore might be due to the removal of clay minerals in the raw coal structure. In addition, it may be said that the presence of silicate minerals in the coal matrix can be induced that the easily removable organic sulfur compounds are converted to thermally stable and non-removable organic sulfur compounds (thiophenic or condensed thiophenic compounds) at these temperatures. Increase in the pyritic sulfur removal of HCl-treated and HCl/HF-treated coal samples may be attributed to the fact that increase of mass and/or heat transport in comparison with untreated coal as a result of elimination of mineral matter.     

投加粉末活性炭对超滤膜去除海水中有机物的影响

超滤膜的有机污染问题是膜法海水预处理技术在海水淡化工程应用面临的重要挑战,粉末活性炭吸附是目前常用的膜前预处理手段之一。本文对比分析了直接超滤和投加粉末活性炭后对海水中有机物的截留能力,利用三维荧光光谱分析了投加粉末活性炭对超滤膜截留有机物的影响机制,并考察了海水超滤过程中通量变化及膜污染情况。研究结果表明,投加粉末活性炭能够强化超滤膜对海水浊度和有机物的去除,当粉末活性炭投量为200mg/L时,整个系统对海水中DOC去除率从直接超滤时的55.1%提高到77.6%。利用粉末活性炭的吸附作用及其在超滤膜表面形成的疏松滤饼层能够显著提高超滤系统对海水中腐植酸类有机物的去除能力。与直接超滤相比,粉末活性炭-超滤系统对改善膜通量的作用有限,但粉末活性炭形成的滤饼层能够避免超滤膜与有机物直接接触,可显著减缓超滤膜的不可逆污染。     

Removal of total ammonia nitrogen (TAN), nitrate and total organic carbon (TOC) from aquaculture wastewater using electrochemical technology: A review

Protein rich wastes from aquaculture systems result in total ammonia nitrogen (TAN), total organic carbon (TOC) and biochemical oxygen demand (BOD). A number of conventional approaches have been adopted for the removal of these wastes in aquaculture ponds and hatcheries with varying degrees of success but they face critical problems such as membrane fouling, high cost or the generation of toxic by-products. To overcome such issues, electrochemical technology is commonly employed. The advantages of electrochemical treatment include high efficiency, ambient operating conditions, small equipment sizes, minimal sludge generation and rapid start-up. An even better system involves bio-electrochemical reactors (BERs), which have the potential to generate energy from wastewater (by means of microbial fuel cells) or a valuable product such as hydrogen (using microbial electrolysis cells). Mechanisms of cathodic nitrate reduction and anodic oxidation in electrochemical and bio-electrochemical technology are reported in this review. Also some work on the simultaneous removal of nitrate and organic matter by Electro-Fenton and microbial fuel cells are elaborated upon. It is apparent that BERs can remove contaminants at high efficiencies (≈ 99%) whilst giving least impact upon the environment.     

饮用水中的天然有机物去除方法探讨

天然有机物的去除对保证水质是至关重要的。本文阐述了天然有机物的性质和危害 ,并对天然有机物的去除方法进行了探讨     

以稻壳为载体的SBR对农村生活污水去除效能分析

为实现高效、低耗处理农村生活污水,以农业废弃物稻壳为材料,对添加稻壳的序批式活性污泥法（SBR）反应器处理人工模拟农村生活污水的效能进行了分析,并研究了稻壳释放和吸附污染物特性。研究结果表明,以稻壳为载体的SBR对有机物和氨氮具有很好的去除效果,当进水有机物和氨氮平均浓度分别为530.77mg/L和35.32mg/L时,二者的去除率分别为90.46%和95.64%,并表现出良好的同步硝化-反硝化特性;短时间内稻壳对模拟废水有机物表现为释放特性,而对氨氮表现为吸附特性;比较而言,稻壳对实际生活污水中有机物则表现为释放和部分吸附特性,而对氨氮则表现为释放特性;长时间浸没试验结果表明,去离子水中浸没稻壳会引起有机物和氨氮浓度的升高。生物作用是以稻壳为载体的SBR对污染物去除的主要原因,稻壳的吸附作用很小。     

Sludge Bio-drying Process at Low Ambient Temperature: Effect of Bulking Agent Particle Size and Controlled Temperature

Sludge bio-drying is an aeration process for the removal of water. The drying process utilizes the bio-heat generated from aerobic degradation of organic matter in sludge. In this study, four trials were run in the winter season at ambient temperatures of between 3°C and 9°C. The physical and chemical changes that occurred during the process were investigated and the impacts of the particle sizes of bulking agents and the controlled-matrix temperature were assessed. Results indicated that the process can start up in winter with a three-day lag, while the total duration was only seven days. The highest water removal rate (of 31.0%) with the least organic matter loss (of 12.2%) was obtained at a lower controlled matrix temperature (of 43°C) with a bulking agent of mixed particle size. As a common bulking agent, straw, which has a small particle size of 2–5 mm, was beneficial for organic matter degradation, while it had a negative effect on water removal. The use of different types of straw (with larger particle size of 20–30 mm) as the bulking agent gave poor performance, in which the organic matter degradation rate was 9.75% and the water removal rate was 25.9%. Higher controlled temperature (53°C) resulted in less aeration but degradation rates were enhanced to 16.8%. The using of lower temperatures (43°C) resulted in lower water removal rate (of 29.2%) and relatively lower biodegradation rate.     

FLOCCULATION/COAGULATION OF NATURAL ORGANIC MATTER FOR PRETREATMENT OF WATER AND WASTE WATER

Characterization of water, waste water and natural organic matter are involved in this paper, and as well as the features of flocculation and coagulation for removing natural organic matter from water and waste water Novel flocculant and coagualant is strongly asked for improving removal efficiency and environment friendly. Enhanced coagulation is introduced to meet the experimental and practical requirement.     

Use of O3 and O3/H2O2 for degradation of organic matter from Bayer liquor towards new resource management: Kinetic and mechanism

Since the quality of bauxite resources has decreased and the organic carbon content has increased, different approaches are explored to remove the organic matter in alumina production. Advanced oxidative processes (AOPs) represent a possibility since they are widely used as an alternative for treating wastewaters to degrade organic pollutant molecules and in hydrometallurgy processes. For this reason, the goal of the project was the ozonation of Bayer liquor for organic matter removal. The ozone concentration was evaluated over time, as well as the H₂O₂ concentration and temperature. Results showed that the total organic carbon (TOC) removal achieved 19% in the most optimized condition with a kinetic rate of 0.0157 h⁻¹ –21.9 mg/L O₃, 0.05 mol/L H₂O₂ at 80°C. The colour of the liquor changed from dark brown to white-yellow, indicating that the size of the organic compounds had decreased. Also, 95.4% of degraded TOC formed CO₂, and almost 50% of the organic matter was oxalate compounds. The energy required for ozone production versus removed organic matter demonstrated that the technique proposed might be technically and economically feasible to be applied in the Bayer process. The study demonstrates the application of AOP in an extremely alkaline condition.     

复合反应器中高浓度有机废水对硝化作用的影响

选用悬浮球形填料作为复合生物反应器的填料,研究有机物去除和硝化作用。研究显示,将进水COD质量浓度从400 mg/L逐渐增加到2 000 mg/L,进水NH3-N质量浓度维持在30 mg/L~45 mg/L运行20天,随着COD质量浓度的逐渐增高,NH3-N的去除率从82%左右降低到-25.9%,硝化反应能力呈逐渐减小的总体趋势。     

Operation of Fixed‐bed Bioreactor for Polluted Surface Water Treatment

Abstract

Dissolved organic matters and ammonia nitrogen are serious contaminants of surface water in Taiwan. These contaminants can interfere with the water treatment process and cause biological instability in the finished water. One solution is to employ a biological treatment stage prior to the conventional water treatment process. A continuous flow biological filter packed with reticulated PU foam was used to remove ammonia nitrogen and organic materials before the conventional water treatment practice. The effect of its operation mode, namely, empty bed contact time (EBCT) and backwash, on the removal efficiencies of ammonia and organic matter was examined. The results suggested that ammonia nitrogen and organic nitrogen can be effectively removed by controlling the operation mode of the biological fixed bed. Efficient ammonia nitrogen removal was achieved upon the combination of the backwash mode with short EBCT or extended EBCT without the backwash. Efficient organic nitrogen and DOC removals were observed at short EBCT without the backwash. This study provides insights into the function of biofiltration, which benefits the design of a fixed‐bed bioreactor for the treatment of polluted surface water.     

Huangpu River water treatment by microfiltration with ozone pretreatment

With the promulgation of more stringent regulations to guarantee the quality of drinking water, low pressure membrane processes are nowadays considered for surface water treatment. But these membranes are sensitive to fouling. In this study ozone is introduced to pretreatment for membrane filtration to get a high quality permeate and improve membrane performance. The organic matter characteristics, such as AMWD of organic matter, hydrophilic/hydrophobic fractions were studied with ozone oxidation. Results show that for Huangpu River water, ozone oxidation offers high percentage of UV absorbance removal than DOC removal. Highest removal of DOC and UV₂₅₄ of 10% and 71% respectively were observed. The dominant organic matter oxidized by ozone was 2-7.0 kDa in terms of molecule distribution investigation. Ozone oxidizes more hydrophobic fraction to hydrophilic one. Changes of organic matter composition improved membrane flux. There is the optimal dosage with ozone of 1.5 mgO₃/L made membrane flux maximum during 0.5-3.0 mgO₃/L ozone dosage. Ozone oxidization provided degradation of macromolecule organic matter, which is responsible to membrane fouling, to small molecule organic substance. Study about the chemical cleaning of the fouled membrane also supports the point that membrane fouling is produced by the organic substance with high molecule weight.     

Combined Pre-Treatment of Coagulation-Ozonation for Saline-Stabilized Landfill Leachates

Coagulated stabilized leachates were ozonated under a continuous regimen at the laboratory scale. Experimental results showed that the coagulation pretreatment allows the removal of complex organic matter related to color in stabilized landfill leachates. Infrared analysis of coagulated organic matter sludges suggests that more than 90% of leachate color is due mainly to the presence of humic acids. These acids are taken from the colloidal particles (0.34–1.0 μm) contained in landfill leachate. The effect of ozone on residual color removal displays a fast kinetic reaction. The ozone absorption process is associated to reactions with easily oxidizable organic compounds, such as those related to color in stabilized landfill leachates. The experimental results of ozone mass transfer revealed that ozone absorption depends on gas velocity and is substantially favored by chemical reaction. The estimated k′_La values (2‐7 s^?1) had the same order of magnitude as those reported in treated wastewater. The enhancement factor (E) was estimated to be in the range 3 to 11.     

Mathematical model for a batch aerated submerged biofilm reactor for organic carbon and nitrogen removal

An aerated submerged biofilm (ASBF) pilot plant has been developed. The present study optimized an inexpensive method of enhanced wastewater treatment. Over a period of three and one half months, a total of 11 batch runs were performed. By the fourth run, the biofilm had matured to the point that it consumed all the ammonia in 40 hours. The investigation aimed to present mathematical models for describing the dynamic behaviors of the dissolved organic matter removal and nitrification in the Aerated Submerged Biofilm (ASBF) for a batch reactor. Based on the experimental data from the batch system of the ASBF pilot plant, mathematical models were developed to predict dissloved organic matter and ammonia nitrogen removal rates as a function of heterotrophic and autotrophic bacteria populations, dissolved organic matter concentrations, ammonia nitrogen concentrations, dissolved oxygen concentrations, and temperature. The mathematical models for dissolved organic matter and ammonia nitrogen removal in ASBF include two differential equations reflecting heterotrophic and autotrophic bacteria populations, and a number of kinetic parameters. Consequently, the results provide a better insight into the dynamic behaviors of heterotrophic and autotrophic biofilm growth and their practical application to wastewater for dissolved organic matter and ammonia nitrogen removal process.     

纳滤对水中有机微污染的去除效果与应用

本文综述了纳滤技术对水中微量的天然有机物、有毒有害有机物(农药和三致物质)、挥发性有机物、可生物降解溶解有机物与可同化有机物等的去除效果、影响因素及应用．指出纳滤作为一种先进的分离技术应用于有机微污染的去除具有明显的优势,可广泛应用于安全优质饮用水的生产中。     

Treating urban dredged silt with ethanol improves settling and solidification properties

The organic matter content in urban dredged silt is high for the indraft of municipal sewage, and it seriously influences the utilization of urban dredged silt. It is necessary to find a method to solve this problem. This paper presents a method of treating the silt with ethanol (STE), considering that ethanol is a good organic solvent which can dissolve many kinds of organic matter, and optimizes the treatment conditions through Box-Benhnken design (BBD) experiment with organic matter removal efficiency as the response. The ideal conditions were as follows: action time, 47 min; ethanol concentration, 41%; ratio of ethanol to silt, 54: 1 ml/g with organic matter removal efficiency of 51.12%. Then, settling and solidification properties of raw silt and STE were explored through laboratory experiments. The results show treating urban dredged silt improved the settling and solidification properties of silt.     

负荷对膜曝气生物反应器去除有机物和硝化的影响

讨论了在模拟生活废水的浓度阶段性变化的情况下,有机物负荷以及氮负荷对膜曝气生物反应器的有机物去除和硝化的影响。结果表明,TOC负荷和TN负荷分别从6.6 g/(m2.d)和3.2 g/(m2.d)到26g/(m2.d)和5.8g/(m2.d)变化,碳氮质量比从2.1到4.6变化时,得到94%～97%的TOC去除率。碳氮质量比从2.1到3.7变化时,硝化率约为90%;当碳氮质量比增加到4.6时,硝化率降到81%。在第一阶段,碳氮质量比为2.85,TN负荷从2.5到9.5 g/(m2.d)变化时,TOC去除率为95%。最大硝化速率和硝化率分别为7.5 g/(m2.d)和90%。和传统的生物膜比较,用膜曝气生物反应器处理废水,可同时提高有机物去除速率和硝化速率。     

HSB微生物技术在有机助剂废水处理中的应用研究

有机助剂生产过程中产生的工业废水，其有机物浓度高、毒性大、不易降解，废水的BOD／COD约为0．1。采用HSB高效微生物技术对有机助剂废话水进行工业小试，考察了该技术对含有苯胺类化合物、硝基苯类化合物、硫氰化物等难降及有毒化合物废水的处理效果。运行结果表明，对COD的去除率为86．3％，对苯胺类的去除率为98％，对硝基苯类的去除率为83％。     

混晶纳米二氧化钛光催化剂处理印染废水的研究

以混晶纳米二氧化钛为光催化剂,研究了pH值、光催化反应时间、纳米二氧化钛的用量及晶型、光源等因素对活性大红BES模拟印染废水和实际印染废水COD降解的处理效果.结果表明,对30 mL活性大红BES模拟印染废水,在溶液pH值为4、催化剂添加量为0.090 g时,紫外灯照射1 h,COD去除率可达到86%;对30 mL实际印染废水,在溶液pH值为9、催化剂添加量为0.150 g时,紫外灯照射1 h,COD去除率达到57%.