油田采出水处理技术现状及发展趋势

油田采出水处理的目的是去除水中的油、悬浮物、添加剂以及其它有碍注水、易造成注水系统腐蚀、结垢的不利成分。所采用的技术包括重力分离、粗粒化、浮选法、过滤、膜分离以及生物法等十几种方法。各油田或区块的水质成分复杂、差异较大,处理后回注水的水质要求也不一样,因此处理工艺应有所选择。研制新型设备和药剂,开发新工艺,应用新技术成为油田采出水处理发展的新趋势。     

软硬性填料对MBR处理效率和膜污染的影响

膜生物反应器（MBR）在污水处理领域的应用日益广泛,填料的投加对MBR污水处理效率和膜污染进程有一定的影响。本文分别向MBR中投加不同量的软性和硬性悬浮填料,研究了悬浮填料对MBR运行效率及膜污染的影响。结果表明,投加填料后MBR对COD、氨氮和总磷等污染物的处理效率有所提高,明显减缓了膜污染的进程。软性填料对MBR的改善效果优于硬性填料,投加20%的软性填料时,系统对COD、氨氮和总磷的去除率分别可达96.53%、98.21%和52.75%,系统运行30天时的膜污染情况比未投加填料的系统减缓了41.43%。通过对比发现软性填料能够为微生物提供更大的生存空间,提高反应器内的微生物量,从而提高MBR对污水的处理效率同时改善膜污染,是一种加强MBR系统的适宜填料,最佳投加量为反应器有效体积的20%。     

Evaluation of the fouling potential of ceramic membrane configurations designed for the treatment of oilfield produced water

During the treatment of oilfield produced water (PW) with ceramic membranes, process efficiency is primarily characterized by the specific permeate flux and the oil separation performance. In addition to membrane properties, the increase in total filtration resistance (fouling) and the decline in permeate flux are strongly dependent on the constituents of the PW as well as process conditions such as trans-membrane pressure and cross-flow velocity. The extensive study presented herein describes the characterization, application and performance of various ceramic membrane filtration technologies designed and developed for the efficient treatment of PW generated from tank dewatering and several oily model systems.     

内循环接触氧化型膜生物反应器部分硝化启动与运行条件

部分硝化-厌氧氨氧化工艺可用于高氨氮废水的经济高效处理,部分硝化是实现该工艺启动和稳定运行的前提。研究构建了连续流的内循环接触氧化型膜生物反应器（ICCOMBR）,对其部分硝化的启动和稳定运行特性进行了研究。结果表明：以普通絮状活性污泥接种,在30℃、氮负荷0.25kg/(m³·d)、溶解氧（DO）2.0～2.5mg/L条件下,18d内成功启动了系统的部分硝化,氨氮去除率（ARE）和亚硝态氮积累率（NAR）分别达到99.16%和84.55%,容积亚硝化速率可达0.126gNO₂-N/(L·d),同时容积硝化速率下降到0.031gNO₃-N/(L·d)。系统的亚硝化率与碱度消耗量呈现良好的线性相关性。部分硝化启动完成后,将氨氮负荷降低为0.1kg/(m³·d),部分硝化功能迅速被破坏,通过降低曝气量将DO从2.0～2.5mg/L降低为1.0mg/L,在6d时间内硝化率从71.4%下降到11.1%,ARE和NAR分别达到98.87%和83.65%,部分硝化性能成功恢复。经过57d的运行,系统内的污泥生物量从接种时的1.85gVSS/L增长为3.47gVSS/L。     

A novel approach to an advanced tertiary wastewater treatment: Combination of a membrane bioreactor and an oyster-zeolite column

A combination of a microfiltration-membrane bioreactor (MBR) and oyster-zeolite (OZ) packed-bed adsorption column was studied for the first time to evaluate the advanced tertiary treatment of nitrogen and phosphorous. The membrane module was submerged in the bioreactor and aeration was operated intermittently for an optimal wastewater treatment performance. Artificial wastewater with COD_cr of 220 mg/L, total nitrogen (T-N) of 45 mg/L, and total phosphorous (T-P) of 6 mg/L was used in submerged MBR with MLSS of 4,000–5,000 mg/L. The experiments were performed during a 100-day period with periodic membrane washing. The results showed that COD_cr could be effectively removed in the MBR alone with over 96% removal efficiency. However, T-N and T-P removal efficiency was slightly lower than expected with only the MBR. The permeate from MBR was then passed through the OZ column for tertiary nutrient removal. The final effluent analysis confirmed that nutrients can be additionally removed resulting in over 90% and 53% removal efficiencies for T-N and T-P, respectively. The results of this study suggest that the waste oyster shell can be effectively reclaimed as an adsorbent in advanced tertiary wastewater treatment processes in combination with a MBR.     

无排泥条件下膜生物反应器污泥混合液可滤性分析

膜生物反应器（MBR）在无排泥条件下运行100 d,定期对溶解性微生物产物（SMP）、SMP分子量分布、胞外聚合物（EPS）中的蛋白质和多糖进行监测,应用修正的污染指数（MFI）考察污泥混合液可滤性的变化。实验表明：长时间无排泥运行模式下将导致污泥混合液可滤性的恶化;污泥混合液上清液中分子量（M_w）大于10 kDa 的SMP浓度对污泥混合液的可滤性产生强烈的负面影响;污泥浓度（MLSS）与混合液可滤性之间关系复杂,MLSS对污泥可滤性的影响存在一个临界值;EPS中的蛋白质60 d后发现可被微生物迅速降解,多糖类物质对污泥混合液可滤性有较强的负面影响。     

Biological treatment of saline wastewaters from marine‐products processing factories by a fixed‐bed reactor

Wastewaters generated by a factory processing marine products are characterized by high concentrations of organic compounds and salt constituents (>30 g dm^?3). Biological treatment of these saline wastewaters in conventional systems usually results in low chemical oxygen demand (COD) removal efficiency, because of the plasmolysis of the organisms. In order to overcome this problem a specific flora was adapted to the wastewater from the fish‐processing industry by a gradual increase in salt concentrations. Biological treatment of this effluent was then studied in a continuous fixed biofilm reactor. Experiments were conducted at different organic loading rates (OLR), varying from 250 to 1000 mg COD dm^?3 day^?1. Under low OLR (250 mg COD dm^?3 day^?1), COD and total organic carbon (TOC) removal efficiencies were 92.5 and 95.4%, respectively. Thereafter, fluctuations in COD and TOC were observed during the experiment, provoked by the progressive increase of OLR and the nature of the wastewater introduced. High COD (87%) and TOC (99%) removal efficiencies were obtained at 1000 mg COD dm^?3 day^?1. © 2002 Society of Chemical Industry     

Biological COD reduction and inorganic suspended solids accumulation in a pilot-scale membrane bioreactor for traditional Chinese medicine wastewater treatment

A pilot-scale test was conducted in a membrane bioreactor (MBR) for 452 days to treat high-strength traditional Chinese medicine (TCM) wastewater from two-phase anaerobic digest effluent. This study focuses on the chemical oxygen demand (COD) reduction and inorganic suspended solid (ISS) accumulation. The wastewater was high in COD, varying daily between 259 and 12,776 mg L⁻¹. Almost all the COD was removed by the MBR system, leaving a COD of <50 mg L⁻¹ in the MBR effluent. This indicated a great potential of the MBR in TCM wastewater reuse. ISS produced in the bioreactor by metabolism of microorganism increased from 265 to 4912 g h⁻¹, which showed that there were large numbers of ISS accumulation in the bioreactor. Two models, built on the material balances of COD and ISS, were developed for the simulation of MBR system performance in the biodegradation of TCM wastewater. Consequently, the kinetic constants including the maximum substrate specific biodegradation rate (V_max), the half-saturation coefficient (K_s) and the inorganic suspended solids growth rate (k) were calculated as V_max, 3.64, 3.82, 4.39 d⁻¹, K_s, 56.4, 225, 394 mg L⁻¹ and k, 265, 888, 4912 mg L⁻¹ d⁻¹ using the operational data at different hydraulic retention times (HRTs). The models well fitted the pilot-scale experimental data, and were able to simulate the COD reduction and ISS accumulation.     

Biological treatment of high salinity produced water by microbial consortia in a batch stirred tank reactor: Modelling and kinetics study

This study was performed to evaluate the potential of acclimated halophilic microorganisms, commercial microorganisms, and microorganisms from polluted soil to degrade crude oil in high salinity oily wastewater (synthetic produced water) at different salt concentrations ranging from zero to 250,000?mg?L^?1 of total dissolved solids (TDS). The highest degradation of crude oil (>60%) was found for acclimated halophilic microorganisms at TDS of 35,000?mg?L^?1. An increase in the TDS concentrations above 145,000?mg?L^?1 leads to a significant decrease in the growth of microorganisms. The results showed that efficiency of the commercial microorganisms was less than the acclimated halophilic microorganisms. The oil biodegradation followed substrate inhibition kinetics and the specific growth rate were fitted to the Haldane model. The biokinetic constants for the saline oily water at TDS of 35,000?mg?L^?1, i.e., Y, K_s, µ_max, and 1/K_i, were 0.21?mg?MLSS/mg crude oil, 0.27?mg?L^?1, 0.019?h^?1, and 0.002?mg?L^?1, respectively.     

Roles of sponge sizes and membrane types in a single stage sponge-submerged membrane bioreactor for improving nutrient removal from wastewater for reuse

Sponge not only can reduce membrane fouling by means of mechanical cleaning and maintain a balance of suspended-attached microorganisms in submerged membrane bioreactor (SMBR), but also can enhance dissolved organic matter and nutrient removal. This study investigated the performance of three different sizes of sponge (S_28-30/45R, S_28-30/60R and S_28-30/90R) associated with continuous aerated SMBR. A laboratory-scale single stage sponge-SMBR (SSMBR) showed high performance for removing dissolved organic matter (>96%) and PO₄-P (>98.8), while coarse sponges such as S_28-30/45R, S_28-30/60R could achieve more than 99% removal of NH₄-N. When three-size sponges (S_28-30/45R, S_28-30/60R and S_28-30/90R) were mixed at a ratio of 1:1:1 and in conjunction with two kinds of membranes (0.1 µm hollow fiber and 2 µm nonwoven), the SSMBR system has proved its generic merits of superior treated effluent quality and less membrane fouling. The NH₄-N and PO₄-P removal were found excellent, which were more than 99.8% and over 99% respectively. Molecular weight distribution also indicated that major fractions of organic matter could be successfully removed by SSMBR.     

An ecologically effective water treatment technique using electrochemically generated hydroxyl radicals for in situ destruction of organic pollutants: Application to herbicide 2,4-D

The electrochemical production of Fenton's reagent by simultaneous reduction of dioxygen and ferric ions on a carbon felt electrode, permits a controlled, in situ generation of hydroxyl (OH^·) radicals. The possibility of using electrochemically produced OH radicals for solving environmental problems is investigated. Continuous and controlled production of hydroxyl radicals was achieved by electrochemical reduction of O₂ in the presence of a catalytic amount of ferric or ferrous ion. These radicals are used for remediation of water containing toxic-persistent-bioaccumulative organic pollutants through their transformation into biodegradable compounds or through their mineralization into H₂O and CO₂. A widely used herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was selected as a model for a toxic organic pollutant. High pressure liquid chromatography (HPLC) was used to quantify the distribution of the hydroxylated products obtained. Rate constants for the hydroxylation reactions of 2,4-D, 2,4-dichlorophenol (2,4-DCP), 2,4-dichlororesorcinol (2,4-DCR) and 4,6-dichlororesorcinol (4,6-DCR) were determined. The mineralization of 2,4-D and its derivatives was followed by total organic carbon (TOC) measurements. More than 95% of 2,4-D and the intermediates generated during the electrolysis can be mineralized.