Impact of salinity on treatment of saline wastewater by sequencing batch biofilm reactor process

High salinity industrial wastewater is difficult to treat using biological treatment system because of the high concentrations of salt.The potential of a sequencing batch biofilm reactor(SBBR)process in treating synthetic high salinity wastewater was evaluated at laboratory scale during a 110-day operation.The reactor was operated in a 12 h cycle,and each cycle consisted of 0.25 h influent addition,8 h aeration,3 h anoxic reaction,0.5 h sedimentation and 0.25 h effluent withdrawal.Gradual increase in salinity gradient was applied during the acclimatization period.The acclimated SBBR system was demonstrated to be an effective process to remove organic compounds and ammonia nitrogen under high salinity conditions with chemical oxygen demand(COD)and ammonia nitrogen(NH3-N)removal efficiencies of 88% and 80%,respectively.The microscopic examination indicated that rather than rotifers or vorticella,the zoogloea,filamentous fungus mingled with a small quantity of swimming infusorians were dominant bacteria in SBBR system.The removal efficiencies close to 80% in COD and 75% in NH3-N were achieved at an organic loading rate(OLR)of 0.96 kg COD/(m3·d),pH of 7.0,salinity of 14 g/L and NH3-N of 30 mg/L.

Study on Influencing Factors and Kinetics of Removal of Ammonia Nitrogen from High Salinity Wastewater by Sodium Hypochlorite Oxidation

The influencing factors and kinetics of oxidative degradation of ammonia nitrogen in high salinity wastewater by sodium hypochlorite oxidation( Na Cl O) were studied. The results showed that the degradation process of ammonia nitrogen by sodium hypochlorite accorded with a pseudo first-order kinetics model,and the influencing factors included Na Cl O dosage,initial concentration of ammonia nitrogen,salinity,temperature,and so on. When Na Cl O dosage was 0. 6%( MCl∶ MN= 13. 76),the reaction rate constant was up to 0. 015 75 min^(-1). The higher the initial concentration of ammonia nitrogen was,the worse the effect of oxidation reaction was. When the initial concentration did not exceed 45 mg/L,the effect on oxidation reaction rate constant increased with the increase of the initial concentration. Low salinity had no effect on ammonia nitrogen oxidation.When salinity was higher than 2. 0%,the inhibition effect on ammonia nitrogen oxidation would increase,and the reaction rate constant decreased obviously with the increase of salinity. The improvement of reaction temperature was beneficial to ammonia oxidation degradation. As temperature increased from 10 to 35 ℃,the reaction rate constant rose from 0. 00188 to 0. 01043 min^(-1).

Performance and Modeling of an Up-flow Anaerobic Sludge Blanket(UASB) Reactor for Treating High Salinity Wastewater from Heavy Oil Production

In this study,an up-flow anaerobic sludge blanket(UASB) reactor was applied to treat the high salinity wastewater from heavy oil production process.At a HRT of ≥24 h,the COD removal reached as high as 65.08% at an influent COD ranging from 350mg/L to 640mg/L.An average of 74.33% oil reduction was also achieved in the UASB reactor at an initial oil concentration between 112mg/L and 205mg/L.These results indicated that this heavy oil production related wastewater could be degraded efficiently in the UASB reactor.Granular sludge was formed in this reactor.In addition,two models,built on the back propagation neural network(BPNN) theory and linear regression techniques were developed for the simulation of the UASB system performance in the oily wastewater biodegradation.The average error of COD and oil removal was-0.65% and 0.84%,respectively.The results indicated that the models built on the BPNN theory were wellfitted to the detected data,and were able to simulate and predict the removal of COD and oil by the UASB reactor.

Singlet oxygen-dominated peroxymonosulfate activation by layered crednerite for organic pollutants degradation in high salinity wastewater

Advanced oxidation processes have been widely studied for organic pollutants treatment in water,but the degradation performance of radical-dominated pathway was severely inhibited by the side reactions between the anions and radicals,especially in high salinity conditions.Here,a singlet oxygen(^(1)O_(2))-dominated non-radical process was developed for organic pollutants degradation in high salinity wastewater,with layered crednerite(CuMnO_(2))as catalysts and peroxymonosulfate(PMS)as oxidant.Based on the experiments and density functional theory calculations,^(1)O_(2)was the dominating reactive species and the constructed Cu-O-Mn with electron-deficient Mn captured electron from PMS promoting the generation of^(1)O_(2).The rapid degradation of bisphenol A(BPA)was achieved by CuMnO_(2)/PMS system,which was 5-fold and 21-fold higher than that in Mn_(2)O_(3)/PMS system and Cu_(2)O/PMS system.The CuMnO_(2)/PMS system shown prominent BPA removal performance under high salinity conditions,prominent PMS utilization efficiency,outstanding total organic carbon removal rate,wide range of applicable pH and good stability.This work unveiled that the^(1)O_(2)-dominated non-radical process of CuMnO_(2)/PMS system overcame the inhibitory effect of anions in high salinity conditions,which provided a promising technique to remove organic pollutants from high saline wastewater.

Effectiveness of a Subsurface Constructed Wetland on the Treatment of Saline Wastewater

This study evaluated the capability of a constructed wetland for treating saline wastewater. A pilot-scale constructed wetland system was set up and was initially operated at low, then increasing salt levels to determine the effect of salinity on the contaminants＇ removal performance. The effect of hydraulic retention time （HRT） variation on treatment efficiency of the reed wetland was also discussed. Average removal efficiencies of the reed （Phragmites australis） wetland were found to be 79.0% for COD, 72.2% for ammonia nitrogen （NH3-N） and 82.8% for total phosphorus （TP）. Reed planting had obvious improvement on COD and NH3-N removal efficiency when compared to an unplanted system. With the seawater proportion in the influent increasing from 20% to 30%, the TP removal efficiency improved obviously. COD removal efficiency of the reed wetland was positively correlated with HRT under high salinity condition, while excess HRT had adverse impacts on the NH3-N and TP removal. Optimal HRT for NH3-N and TP removal was 4 days. Results obtained can be beneficially used to improve the use of constructed wetlands in saline wastewater treatment.

Isolation of a Halophilic Bacterium, Bacillus sp. Strain NY-6 for Organic Contaminants Removal in Saline Wastewater on Ship

The objective of this research was to examine if certain strains of Bacillus bacteria, could survive in dry powder products and if so, could the bacteria degrade organic contaminants in saline wastewater on a ship. As part of the study, we isolated 7 domesticated strains named NY1, NY2,..., and NY7, the strain NY6 showed to have the best performance for organic matter degradation and could survive in dry powder more than 3 months. NY6 was identified as Bacillus aerius, based on the morphological and physic-chemical properties. Its optimal growth conditions were as follows： salinity was 2%; temperature was 37℃; pH was in 6.5-7.0; best ratio of C： N： P was 100：5：1. The capability of its dry powder for Chemical Oxygen Demand （COD） removal was 800mg COD/g in synthesized marine wastewater with 2% salinity. The spores in the dry powder were 1.972×108 g-1.

Removal of Nitrogen and Phosphorus from Saline Wastewater Using Up-Flow Sludge Blanket Filtration Process

There is recent trend of providing additional treatment of wastewater beyond tertiary level. The purpose is to refine water to a quality that is safe for reuse for unrestricted irrigation and other non potable uses. For this purpose, Kuwait has built and operated an advanced wastewater treatment plant with capacity of 500,000 m3·dl. This plant providing treatment beyond tertiary utilizes the process of Ultra Filtration （UF） and Reverse Osmosis （RO）. The reject water of this unit contains high concentration of total nitrogen and total phosphate. Safe disposal of this water into the environment or possible reuse needs substantial reduction of these chemicals. In this study, a bench scale up-flow sludge blanket filtration system was investigated. The system operated with an average Hydraulic-Retention Time （HRT） of 19 h, whereas, sludge age varied within the range of 14 days to 16.5 days. The results show that the average removal efficiencies of the system for Biological Oxygen Demand （BOD）, Chemical Oxygen Demand （COD） were over 86% and 82% respectively. The phosphate and nitrogen＇s average removal were found to be 50% and 45% respectively.

Effect of Salinity Variations on the Performance of Activated Sludge System

To investigate the influence of salinity variations on the performance of activated sludge systems, treating domestic wastewater. Methods The completely mixed reactor was used and operated in a batch-wise mode. The activated sludge taken from the Gaobeidian Wastewater Treatment Plant was used as a seeding sludge. Total organic carbon (TOC), oxygen uptake rate (OUR) and suspended solids (SS) were used as parameters to characterize the performance of the treatment systems. TOC was measured using a TOC-analyzer (TOC-5000, Japan). The OUR value was measured with a dissolved oxygen meter (YSI model-58). SS was measured gravimetrically. Results The TOC removal efficiency and the OUR value of activated sludge were not deteriorated when the NaCl shock concentration was less than 0.5 g/L. However, when the NaCl shock concentrations were up to 10g/L and 20 g/L, the OUR of activated sludge was reduced by 35% and TOC removal efficiency was dropped by 30%, compared with the control experiment without NaCl shock loading. Conclusion The effect of NaCl shock loading on the activated sludge wastewater treatment system is dependant upon the NaCl concentrations and the degree of influence can be inferred through the change of substrate utilization rate at different shock NaCl loadings.

Salinity exchange between seawater/brackish water and domestic wastewater through electrodialysis for potable water

Two-thirds of the world’s population has limited access to potable water.As we continue to use up our freshwater resources,new and improved techniques for potable water production are warranted.Here,we present a general concept called“salinity exchange”that transfers salts from seawater or brackish water to treated wastewater until their salinity values approximately switch,thus producing wastewater with an increased salinity for discharge and desalinated seawater as the potable water source.We have demonstrated this process using electrodialysis.Salinity exchange has been successfully achieved between influents of different salinities under various operating conditions.Laboratory-scale salinity exchange electrodialysis(SEE)systems can produce high-quality desalinated water at~1 mL/min with an energy consumption less than 1 kWh/m3.SEE has also been operated using real water,and the challenges of its implementation at a larger scale are evaluated.

硫磺回收装置烟气碱法脱硫工艺存在问题及解决方案

目的对140 kt/a硫磺回收装置新增烟气碱洗单元的运行情况进行总结,分析烟气碱洗单元运行过程中出现的异常情况,并提出应对措施。方法①总结碱洗单元的运行情况,对操作参数及烟气排放情况进行分析;②将冲洗水由工业水改为除盐水,同时稳定控制碱液pH值,解决了烟气碱洗塔压降增大的问题;③优化工艺操作,对碱洗塔与循环槽连通管线进行改造,解决了碱洗塔液位波动的问题;④保证氧化空气供给,调整碱液pH值,防止急冷塔氨逃逸,解决了含盐废水超标的问题。结果解决了烟气碱洗单元运行过程中出现的问题,该工艺单元于2017年7月建成投运,稳定运行至2022年3月装置大修,连续运行时间超过1700 d。结论实现了装置的长周期稳定运行,烟气中SO_(2)排放稳定达标,远低于排放标准的要求,可为同类装置提供参考。

选择性电渗析盐分离和资源化的研究进展

概括了目前选择性电渗析中阴离子交换膜提高盐分离效果的主要方式,同时就目前选择性电渗析技术的局限性进行了总结,并对离子交换膜、电极的开发和工艺优化进行了展望。

基于零排的高盐废水处理技术经济比选分析

高盐废水零排工艺中常有超滤、反渗透、MVR蒸发等工艺的组合,但因为零排的水平衡问题,其组合顺序影响投资规模和运行成本。以某资源化项目的废水零排处理工艺为例,对不同的工艺路线进行技术经济分析,研究发现直接采用MVR蒸发全量处理废水能耗过高,采用DTRO减量化后再蒸发结晶更经济,分析成果可为类似项目决策提供参考。

生物增效技术促进炼油废水降氮效果分析

介绍了针对外排氨氮标准不断提升,炼油含盐废水处理装置出水氨氮控制难度增加,在一段时期常出现波动情况,投加硝化菌进行生物增效处理达标的生产试验。对试验过程和试验前后含盐污水处理装置进、出水数据进行分析,对照出水pH值与硝化系统的关系,找到了出水氨氮异常升高主要是污水处理系统碱度降低引起的根本原因。证明了投加硝化菌进行生物增效的方法可作为恢复污水生化系统快速建立硝化系统,恢复氨氮去除能力的有效应急手段。

高盐有机废水电催化氧化过程有机氯代物生成势初探

电催化氧化法适用于处理制浆造纸废水回用产生的膜浓缩液等高盐有机废水,但过程中Cl-等阴离子或将产生可吸附有机氯化物(AOX),存在二次污染。本研究以木素磺酸钠为模拟污染物,以NaCl和NaHCO_(3)为电解质,探究Pt-Ti和掺硼金刚石(BDD)两个电极体系下污染物转化、降解及AOX生成势。研究表明,Cl-促进木素磺酸钠的转化和脱色,但中间氯代产物阻碍TOC持续降低,且AOX最终为50~70mg/L。因此,电催化技术应用时,需实现AOX源头减量与末端处理,避免潜在风险。

反硝化脱氮工艺在污水深度处理中的应用与优化

介绍了污水深度处理装置采用反硝化脱氮工艺处理炼油化工混合污水的工艺流程、原理和特点,并针对开车调试阶段的快速启动和日常运行中所遇到的水量衰减问题进行分析和处理。从开车到正式运行经过半年时间的摸索和调整,反硝化滤池出水总氮稳定在4~8 mg/L,运行水量达到500 t/h以上。

高盐废水厌氧生物处理的强化方法研究

通过厌氧消化瓶小试实验和厌氧中试装置实验相结合的研究方法,驯化培养耐盐厌氧菌实现制药高盐废水的有机物质降解能力提升和氯离子浓度有效降低。首先,通过厌氧小试针对COD≈2500 mg/L,ρ(Cl^(-))≈10000 mg/L的高盐制药废水选取五种外源投加物展开实验,每种投加物设置六个不同投加量平行试验组,实验结果表明,外源投加相容性溶质,可增强厌氧耐盐菌在高盐环境下的活性,投加2 mmol/L甜菜碱对厌氧耐盐菌活性提升效果最佳,COD去除率较空白组提升约8%,达到60.83%,氯离子去除率为8.63%,实现了对厌氧处理高盐废水的有效强化。其次,利用多点回流式两相厌氧深度反应器处理ρ(Cl^(-))≈10000 mg/L的实际制药废水,在20 t/d的中试处理规模下,有效运行75天,厌氧处理效果良好,在稳定运行状态下废水COD去除率达到60%左右,氯离子吸附截留去除率为10%。

“共价”型全疏/滑移表面构建及膜蒸馏性能研究

由于孔隙润湿、矿物结垢或结构不稳定等引起的膜功能层失效问题是膜蒸馏(MD)技术的关键挑战,严重影响其长期运行稳定性.本文提出一种“全共价”接枝修饰的方法,制备具有优异MD性能的全疏/滑移膜蒸馏膜材料.具体而言,通过使用聚多巴胺型插层将纳米硅球共价键合在聚偏氟乙烯(PVDF)膜表面,并采用巯基-烯烃点击化学进行直接表面氟化改性.通过接触角测试,发现所制备的PDA/PVDF-C膜具有超高的静态水接触角(163.5°±0.9°)和极低的滚动角(5.6°±1.2°).在不同表面张力液体的侵蚀作用下,该膜均未出现膜孔的润湿现象,体现出优异的抗润湿性能.由于该膜表面特殊的全疏/滑移特性,该膜能够持久并稳定地处理含有表面活性剂的高盐卤水,延缓石膏垢的形成,运行性能显著优于商用疏水膜.该膜初始通量约为23.5 L/(m^(2)·h),运行前后始终保持对盐高达99%的截留.本研究提供了一种新颖而有效的方法开发“全共价”型MD膜,该膜具有优异的抗润湿、抗无机结垢以及结构稳定性,可用于高盐废水的资源化处理.

高盐有机废水处理技术研究进展

综述了高盐有机废水现有处理技术的研究现状,重点介绍了高级氧化法､吸附法､电解法和萃取法等;膜处理技术与热法处理技术可对废水中的盐分进行脱除;指出新兴集成技术是未来处理高盐有机废水的发展趋势。

石油石化含盐有机废水脱盐处理技术及资源化研究进展

淡水资源日益短缺,可用水资源与水需求之间存在巨大矛盾。油气开采和石油炼制过程中要消耗大量水资源,同时伴生大量高含盐有机废水,因此,废水处理及资源回用是解决石油石化行业水资源供需矛盾的重要手段。综述了含盐有机废水脱盐处理技术的研究进展,分析了热蒸发浓缩技术、离子交换技术和膜分离技术以及相关组合工艺处理石油石化含盐有机废水与资源再利用的潜力。

SiO_(2)/PVDF渗透膜在高盐废水处理中的性能研究

疏水性差热导率高是制约膜蒸馏在高盐度废水处理领域运用的关键技术参数。为提高膜的疏水性的同时降低膜的导热性能,对自制的SiO_(2)/PVDF复合膜进行了分子模拟和污染物为Ni^(2+)、Co^(2+)和Mg^(2+)的耐污染实验。通过Materials Studio (MS)软件建立了膜的分子模型。结果表明,羟基含量为40%膜的导热系数最低;采用膜蒸馏+MVR(机械蒸汽再压缩蒸发技术)组合工艺可降低30.61%的处理成本。各污染物与膜表面的非键作用力中,氢键作用能(E_(el))为负值且是污染物富集在膜表面的主要作用力。此外,Ni^(2+)离子对膜的渗透性能影响最大。