Application Progress of Nanofiltration Combination Technology in the Treatment of Landfill Leachate

Under the impetus of environmental protection policies,the discharge requirements for leachate are becoming more and more stringent.Therefore,the treatment technology of landfill leachate has become a hot research topic at present.In this paper,the chemical composition and water quality characteristics of landfill leachate were briefly introduced,and the characteristics and performance of nanofiltration technology were summarized at first.Afterwards,the recent advances in the application of nanofiltration combination technology in the treatment of landfill leachate at home and abroad were summarized,and the research and application of the combination of membrane separation,chemical coagulation,chemical oxidation and adsorption methods with nanofiltration membrane in the treatment of landfill leachate were mainly introduced.Finally,it is proposed that the combination of nanofiltration technology is feasible and economical,and its reasonable selection and optimization are the directions of future research and have good application prospects.

Research on Treatment of Landfill Leachate Polluting Groundwater by Orthogonal Test

Through PRB simulated device and orthogonal test,we discussed the treatment effect of groundwater polluted by landfill leachate with three reaction mediums of zero-valent iron powder,activated carbon and zeolite. We considered four factors of iron powder mass,activated carbon mass,particle size of iron powder and zeolite mass,and designed a two-level orthogonal test. It concluded that effluent pH appeared to fall or rise as the reaction proceeded,which changed during 7- 8. The removal rates of CODCrin eight reactors were during 60. 7%- 78. 3%,and the removal rates of NH3-N were during 34. 0%- 58. 8%. Activated carbon mass and the interaction of iron powder mass and activated carbon mass had significant influences on the removal of CODCr,while iron powder mass,particle size of iron powder and zeolite mass had insignificant influences on the removal of CODCr. Zeolite mass and activated carbon mass had significant influences on the removal of NH3,while iron powder mass,particle size of iron powder and the interaction with activated carbon mass had insignificant influences on the removal of NH3-N.

Study of Biological Methods in Landfill Leachate Treatment

Landfill leachate is mainly the result of precipitation of water into the layers of buried waste, and biochemical reactions of waste that has dangerous substances and pollutants that lead to the contamination of surface and groundwater resources. Therefore, it must be collected and treated properly. The investigation of various biological methods in leachate treatment, their advantages and disadvantages, and their effect on reduction of COD (chemical oxygen demand) are the objectives of this study. Reviewed processes include anaerobic and aerobic sequencing batch reactor, up-flow anaerobic sludge blanket, moving-bed biofilm reactor, membrane bioreactor, and aerated lagoons, lead to reduction of biodegradability pollutants in different circumstances. The present study has indicated that the most and the least reduction of COD has been through aerated lagoon (95%) and moving-bed biofilm reactor (8%), respectively.

ANALYSIS AND IMPROVEMENT ON LANDFILL LEACHATE TREATMENT PROCESS OF MUNICIPAL SOLID WASTE

According to different mechanism of microbial degradation of organics, this article divided the treatment processes of garbage landfill into four kinds, analyzed each kind of the treatment leachate process and presented a better improved process. (Author abstract) 4 Refs.

Microplastics in landfill leachate:Sources,detection,occurrence,and removal

Due to the accumulation of an enormous amount of plastic waste from municipal and industrial sources in landfills,landfill leachate is becoming a significant reservoir of microplastics.The release of microplastics from landfill leachate into the environment can have undesirable effects on humans and biota.This study provides the state of the science regarding the source,detection,occurrence,and remediation of microplastics in landfill leachate based on a comprehensive review of the scientific literature,mostly in the recent decade.Solid waste and wastewater treatment residue are the primary sources of microplastics in landfill leachate.Microplastic concentration in raw and treated landfill leachate varied between 0-382 and 0-2.7 items L^(−1).Microplastics in raw landfill leachate are largely attributable to local plastic waste production and solid waste management practices.Polyethylene,polystyrene,and polypropylene are the most prevalent microplastic polymers in landfill leachate.Even though the colors of microplastics are primarily determined by their parent plastic waste,the predominance of light-colored microplastics in landfill leachate indicates long-term degradation.The identified morphologies of microplastics in leachate from all published sources contain fiber and fragments the most.Depending on the treatment method,leachate treatment processes can achieve microplastic removal rates between 3%and 100%.The review also provides unique perspectives on microplastics in landfill leachate in terms of remediation,final disposal,fate and transport among engineering systems,and source reduction,etc.The landfill-wastewater treatment plant loop and bioreactor landfills present unique difficulties and opportunities for managing microplastics induced by landfill leachate.

Biological nutrient removal by internal circulation upflow sludge blanket reactor after landfill leachate pretreatment

The removal of biological nutrient from mature landfill leachate with a high nitrogen load by an internal circulation upflow sludge blanket （ICUSB） reactor was studied. The reactor is a set of anaerobic-anoxic-aerobic （A^2/O） bioreactors, developed on the basis of an expended granular sludge blanket （EGSB）, granular sequencing batch reactor （GSBR） and intermittent cycle extended aeration system （ICEAS）. Leachate was subjected to stripping by agitation process and poly ferric sulfate coagulation as a pretreatment process, in order to reduce both ammonia toxicity to microorganisms and the organic contents. The reactor was operated under three different operating systems, consisting of recycling sludge with air （A^2/O）, recycling sludge without air （low oxygen） and a combination of both （A^2/O and low oxygen）. The lowest effluent nutrient levels were realised by the combined system of A^2/O and low oxygen, which resulted in effluent of chemical oxygen demand （COD）, NH3-N and biological oxygen demand （BOD5） concentrations of 98.20, 13.50 and 22.50 mg/L. The optimal operating conditions for the efficient removal of biological nutrient using the ICUSB reactor were examined to evaluate the influence of the parameters on its performance. The results showed that average removal efflciencies of COD and NH3- N of 96.49% and 99.39%, respectively were achieved under the condition of a hydraulic retention time of 12 hr, including 4 hr of pumping air into the reactor, with dissolved oxygen at an rate of 4 mg/L and an upflow velocity 2 m/hr. These combined processes were successfully employed and effectively decreased pollutant loading.

Bioremediation strategies of palm oil mill effluent and landfill leachate using microalgae cultivation:An approach contributing towards environmental sustainability

Palm oil mill effluent(POME)is defined as the wastewater that contains high concentrations of organics,nutrients and oil and grease generated from the production process of palm oil.Therefore,proper discharge and management of POME is important to avoid deleterious impact on the environment.In fact,solid waste generation is a precursor for its disposal issues as most of the solid waste generated in developing nations is dumped into landfills.This has led to the threat posed by the generation of landfill leachate(LL).LL is a complex dark coloured liquid consisting of organic matter,inorganic substances,trace elements and xenobiotics.Hence,it is essential to effectively treat the landfill leachate before discharging it to avoid contamination of soil,surface&groundwater bodies.Conventional treatment methods comprises of physical,biological and chemical treatment,however,microalgal-based treatment could also be incorporated.Furthermore,with the benefits offered by microalgae in valorisation,the application of microalgae in POME and leachate treatment as well as biofuel production,is considerably viable.This paper provides an acumen of the microalgae-based treatment of POME and LL,integrated with biofuel production in a systematic and critical manner.The pollutants assimilation from wastewater and CO_(2)biosequestration are discussed for environmental protection.Cultivation systems for wastewater treatment with simultaneous biomass production and its valorisation,are summarised.The study aims to provide insight to industrial stakeholders on economically viable and environmentally sustainable treatment of wastewaters using microalgae,and eventually contributing to the circular bioeconomy and environmental sustainability.

Landfill leachate treatment by MBR: Performance and molecular weight distribution of organic contaminant

A membrane bioreactor (MBR) with an air-lift bioreactor and gravity flow is applied to treating landfill leachate. More than 99% of BOD5 (biochemical oxygen demand for five days) removal effi-ciency is achieved with less than 35 mg/L of BOD_5 in the effluent at less than 1.71 kg BOD5/m^3·d of BOD_5 loading rate. When DO (dissolved oxygen) is maintained at the range of 2.3―2.8 mg/L and the loading rate of NH_4^+-N (ammonium nitrogen) is kept at 0.16― 0.24 kg NH_4^+-N/m^3·d, the NH_4^+-N in the effluent is less than 15 mg/L. However, compared with high removal rates of BOD_5 and NH_4^+-N, the removal effi-ciency of soluble chemical oxygen demand (SCOD) varies between 70% and 96%. The investigation of molecular weight (MW) distribution has been carried out by the gel permeation chromatography (GPC) so as to understand the fate of organic matters in the MBR treating of landfill leachate. Results indicate that organic matters of the landfill leachate are composed of a high MW fraction (MW of the peak, MWp = 11480―13182 Da) and a low MW fraction (MWp = 158―275 Da). The high MW fraction is not biode-gradable, but can be decreased with microfiltration membrane. The most of the low MW fraction is bio-degradable, but the residue of the low MW fraction is able to permeate through the membrane, thus re-sulting in high SCOD in the effluent of the MBR.

Treatment of landfill leachate by immobilized microorganisms

This paper focuses on the outcome and the main performance of the immobilized microbial that treats landfill leachate. Based on the analysis of COD and ammonia-nitrogen of the influent and effluent, research was done on the high removal efficiency of COD and ammonium nitrogen by immobilized microbial. The leachate composition was analyzed qualitatively using GC-MS before and after being treated. Biological loading of efficient microbial flora on the carrier was measured by Kjeldahl’s method. Finally, the patterns of immobilized microbe were observed through scanning electron microscopy (SEM). The results showed that in immobilized microorganisms system, the efficiencies of COD and nitrogen were 98.3% and 99.9%, respectively. There was a great reduction of organic components in effluent. When the immobilized biomass on the carrier was 38 g·L?1 (H2O), the filamentous microorganism was highly developed. There was no inhibitory effect on the nitrobacteria and nitrococcus, when ammonia was over 200 mg·L?1 and NH3 over 150 mg·L?1. At a high organic loading, it still had good nitrification. This paper also compares the performance of immobilized microbial with free microbial under the same condition. The immobilized microbial technology demonstrated better than the latter in all aspects.

Photoassisted fenton oxidation of refractory organics in UASB-pretreated leachate

Nearly 91% of organic pollutants in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket) process followed by the fenton coagulation. The COD (chemical oxygen demand) of leachate was lowered from an average of 5620 mg/L to 1910 mg/L after the UASB treatment at 37℃, and was further lowered to 513 mg/L after fenton coagulation. The remaining refractory residues could be further removed by photochemical oxidation with the addition of H 2O 2. The BOD/COD ratio was greatly increased from 0.062 to 0.142, indicating the biodegradability of organic residues was improved. The photochemical oxidation for the fenton\|coagulation supernatant was most effective at pH 3\_4, with the addition of 800 mg/L of H 2O 2, and UV radiation time of 30 minutes. The final effluent contained only 148 mg/L of COD, 21 mg/L of BOD(biochemical oxygen demand) and 56 mg/L of TOC (total organic carbon).

SBR-Fenton-两级BAF组合工艺处理垃圾渗滤液的研究

垃圾渗滤液经过“UASB-短程硝化-厌氧氨氧化”工艺处理后,出水COD=1942~2062 mg/L、BOD_(5)=268~380 mg/L和ρ(TN)=100~140 mg/L,BOD_(5)/COD=0.13~0.18,污染物浓度仍很高,可生化性差。采用“SBR-Fenton-两级BAF”组合工艺对渗滤液厌氧氨氧化出水进行深度处理,SBR采用间歇曝气方式运行,ρ(DO)=3~6 mg/L、ρ(MLSS)=3500 mg/L、BOD_(5)污泥负荷为0.3 kg/(kg·d)、HRT=5 h,Fenton反应的条件为:pH=4.0、n(Fe^(2+))/n(H_(2)O_(2))=1∶3、m(H_(2)O_(2))/m(COD)=2∶1;两级BAF系统中,一级BAF为缺氧运行,二级BAF分上下两个分区,下分区的运行状态可根据TN浓度灵活切换为缺氧或好氧状态。运行结果表明:出水COD、BOD_(5)、NH_(4)^(+)-N和TN分别为65~83、4~9、0.04~0.21、22~31 mg/L,平均去除率分别为96.1%、98.0%、99.4%和77.7%,运行成本约12.9元/t,系统运行稳定,抗TN冲击负荷强,没有浓缩液产生,出水指标均优于《生活垃圾填埋场污染控制标准》(GB 16889-2008)表2排放标准,可实现渗滤液的全量化处理。

基于臭氧氧化的垃圾渗滤液深度处理工艺优化及中试验证

针对实际垃圾渗滤液深度处理工艺流程优化开展中试实验。深度处理采用混凝沉淀+臭氧氧化+生物活性碳工艺,针对垃圾渗滤液传统工艺过程中的MBR出水、纳滤浓缩液的处理效果和运行成本进行研究。结果表明:以臭氧氧化为基础的深度处理工艺经过参数优化调整后,处理MBR出水时有机物、氨氮和总氮去除率分别为97.3%、71.76%和42.26%,处理纳滤浓缩液时有机物、氨氮和总氮去除率分别达到98.82%、74.41%和22.53%。其中,臭氧氧化对有机物处理能力最强,深度处理后COD浓度可直接满足排放限值,但是氨氮在后续的臭氧氧化环节和生物活性碳吸附环节存在较大波动。长期成本核算分析表明:处理MBR出水的运行成本为约92.10元/吨;处理纳滤浓缩液的运行成本为约166.00元/吨。最后根据中试研究成果实现了以臭氧氧化为基础的纳滤浓缩液处理工艺的工程转化,为该工艺市场应用奠定基础。

剩余污泥有机质资源回收利用原位驱动晚期垃圾渗滤液深度脱氮——一种具有显著能源优势的创新生物技术

The sustainable recovery and utilization of sludge bioenergy within a circular economy context has drawn increasing attention,but there is currently a shortage of reliable technology.This study presents an innovative biotechnology based on free nitrous acid(FNA)to realize sustainable organics recovery from waste activated sludge(WAS)in-situ,driving efficient nitrogen removal from ammonia rich mature landfill leachate by integrating partial nitrification,fermentation,and denitrification process(PN/DN-F/DN).First,ammonia((1708.5±142.9)mg·L^(-1))in mature landfill leachate is oxidized to nitrite in the aerobic stage of a partial nitrification coupling denitrification(PN/DN)sequencing batch reactor(SBR),with nitrite accumulation ratio of 95.4%±2.5%.Then,intermediate effluent(NO_(2)^(-)-N=(1196.9±184.2)mg·L^(-1))of the PN/DN-SBR,along with concentrated WAS(volatile solids(VSs)=(15119.8±2484.2)mg·L^(-1)),is fed into an anoxic reactor for fermentation coupling denitrification process(F/DN).FNA,the protonated form of nitrite,degrades organics in the WAS to the soluble fraction by the biocidal effect,and the released organics are utilized by denitrifiers to drive NOx-reduction.An ultra-fast sludge reduction rate of 4.89 kg·m^(-3)·d^(-1) and nitrogen removal rate of 0.46 kg·m^(-3)·d^(-1) were realized in the process.Finally,F/DN-SBR effluent containing organics is refluxed to PN/DN-SBR for secondary denitrification in the post anoxic stage.After 175 d operation,an average of 19350.6 mg chemical oxygen demand organics were recovered per operational cycle,with 95.2%nitrogen removal and 53.4%sludge reduction.PN/DN-F/DN is of great significance for promoting a paradigm transformation from energy consumption to energy neutral,specifically,the total benefit in equivalent terms of energy was 291.8 kW·h·t^(-1) total solid.

强效电化学-臭氧耦合工艺的渗滤液深度处理特性

以垃圾渗滤液二级出水非膜法深度处理为目的,构建以复合式阴极和形稳阳极为核心的强效电化学反应单元,其中复合式阴极由磁铁棒、碳毡和铁粉组成,起到Fe2+的析出和渗滤液中硝态氮的还原作用;形稳阳极为商用Ti/RuO2-IrO2电极,起到活化渗滤液中Cl-、产生活性氯、氧化去除渗滤液中氨氮和有机物的作用,并将二者的强效电化学反应与臭氧氧化作用于同一单元,构建了强效电化学-臭氧耦合工艺,以此强化渗滤液二级出水有机物和总氮的去除。结果表明,耦合工艺在电流强度为1.5 A、初始p H值为7、铁粉吸附密度为0.42 g/cm^(2)、臭氧投加量为4.58 mg/min时,对COD及TN的去除率分别为46.46%和81.70%。通过红外光谱(FT-IR)、电子顺磁共振波谱(EPR)、循环伏安曲线(CV)探究工艺对有机物的反去除机理,结果表明,耦合工艺中产生了·OH与·Cl多种活性物质,强化了渗滤液中脂肪族、酯、醚、酚等有机物的去除,提高了渗滤液的可生化性。耦合工艺与SBR小型生化系统联用后出水达到《生活垃圾填埋场污染控制标准》(GB 16889-2008)要求。

臭氧及其组合工艺处理垃圾渗滤液的研究进展

综述了臭氧及其催化氧化方法处理垃圾渗滤液的新型高级氧化技术,对所涉及的机制进行了解析;介绍了不同催化氧化方式处理垃圾渗滤液的原理,对比了各种处理方法的优势及不足。针对催化臭氧氧化技术在垃圾渗滤液领域的应用前景做出了展望。

生活垃圾填埋场反渗透膜浓缩液回灌垃圾堆体对渗沥液水质影响

文章以东莞市3座已临时封场的生活垃圾填埋场为研究对象,跟踪、收集和分析了时间跨度为1年的渗沥液原水水质中COD_(Cr)、BOD_(5)、氨氮、TN、TP、电导率、SS主要污染物浓度随反渗透膜浓缩液回灌垃圾堆体的浓缩液量变化的数据。研究发现,当浓缩液回灌量大于临界量后,渗沥液污染物中的SS、BOD5、电导率浓度与浓缩液回灌量的平方均呈现较为明显正相关性,而浓缩液回灌临界量与填埋场存量垃圾量和渗沥液产生量也呈正相关。浓缩液回灌会造成垃圾堆体渗沥液的各污染物浓度的升高,其中对电导率影响最大,其次是有机污染物,然后是TN、氨氮,最后是SS和TP,其中对TP影响最小。浓缩液回灌会导致渗沥液水质中电导率和总溶解性固体急剧增加并超过处理设施的进水水质浓度限制,将严重影响采用以蝶管式反渗透(DTRO)为主体的渗沥液处理设备的正常运行。因此,文章建议不应采用浓缩液回灌垃圾堆体的方式对浓缩液实施处理。

铁碳还原与活性炭吸附法进行垃圾渗滤液的处理

随着城镇化进程的加速推进,我国的城市垃圾越来越多,我们以城市垃圾渗滤液为研究对象,从垃圾渗滤液的形成及特点出发,结合国内外的渗滤液处理工艺,我们采用了铁碳还原、UASB、AAO、活性炭等处理工艺,更加经济有效地去除污水当中的COD和较难处理的NH3-N,特点是只采用成熟的污水处理工艺来实现达标排放的目的,而未采用膜法处理,避免了膜的反冲洗及浓水处理等较难解决的问题,确保其能够稳定可靠地运行。

温度对垃圾渗滤液生化处理过程中氨氮去除的影响研究

为解决垃圾渗滤液处理工程中常出现夏季高温导致生化污泥失活、出水氨氮不达标的问题,利用杭州市某垃圾中转站的渗滤液和活性污泥,探究了温度对垃圾渗滤液生化处理过程中氨氮去除的影响。通过小试试验探究得出,高温条件下活性污泥对氨氮的去除效果随温度的升高而逐渐降低;当生化系统温度小于40℃时,简单的降温措施即可恢复污泥的活性;当活性污泥受到40℃以上的高温损伤后,生物膜结构受到破坏而彻底失活,生化系统对氨氮的去除率降至20%以下,此时仅通过降温措施并不能有效恢复活性,需重新接种污泥或添加硝化菌剂方能快速恢复氨氮去除功能。因此,在垃圾渗滤液处理工程中,应通过设置冷却塔等措施避免活性污泥处于40℃以上的高温环境中。

餐厨垃圾废水作为外加碳源与生活垃圾渗滤液协同处理的研究

以餐厨垃圾废水作为外加碳源,投加到生活垃圾渗滤液一级A/O生化系统中与生活垃圾渗滤液协同处理,进行了现场试验,研究了餐厨垃圾废水投加量对COD、氨氮、TN、TP的去除效率的影响,试验表明各污染物的去除效率均随餐厨垃圾废水投加比例的提高而增大,当餐厨垃圾废水的投加比例为6.76%时,COD、氨氮、TN、TP的去除率最高分别可达96.06%、98.75%、72.71%和97.38%,最高平均去除容积负荷分别可达1.177 kgCOD/(m^(3)·d)、0.212 kg氨氮/(m^(3)·d)、0.416 kgTN/(m^(3)·d)和0.0055 kgTP/(m^(3)·d),表明餐厨垃圾废水能促进生物脱氮作用,提高生化系统TN的去除效率,减少生物脱氮处理药剂成本,同时餐厨垃圾废水也得到了有效处理。

纳米热处理黄铁矿催化电芬顿降解腐殖酸

腐殖酸是垃圾渗滤液中高浓度有机污染物的主要成分,使用纳米热处理的黄铁矿催化电芬顿工艺降解模拟腐殖酸废水和垃圾渗滤液。对热处理黄铁矿进行了表征,结果表明热处理使黄铁矿发生相变,增大了比表面积,提高了亚铁离子和多硫化物相对质量分数。探究了黄铁矿的热处理温度,阳极种类、电流密度、催化剂浓度和pH对腐殖酸的降解影响,讨论了阳极种类和电流密度对能耗比的影响。结果表明,热处理700℃的黄铁矿表现出更好催化性能,在优化条件下(BDD阳极、30 mA/cm^(2)、催化剂浓度1 g/L、pH 2.5),去除了90.63%的TOC,实现了较低的能耗比。使用该工艺处理实际垃圾渗滤液,TOC和COD分别去除了70%和66%,并且提高了垃圾渗滤液可生化性。