Simultaneous nitrification-denitrification in slow sand filters

While the ability of slow sand filters to remove total suspended solids (SS), turbidity, and organics from wastewaters is well known, this study has demonstrated that they can also achieve simultaneous nitrification-denitrification, producing effluent total Kjedahl nitrogen (TKN) and total nitrogen (TN) concentrations as low as 0.6 and 1.5mg/l, respectively, utilizing particulate and slowly biodegradable COD in the process. The impact of filtration rates in the range of 0.15-0.38m/h, filter depth of 0.5-1.5m, and sand size 0.3-0.5mm on nitrogen removal processes at temperatures of 10-39 degrees C was assessed. Nitrification efficiency, denitrification efficiency, and total nitrogen removal efficiency correlated well with filtration rate and sand size only, with all three parameters inversely proportional to the square root of the aforementioned two process variables. Nitrification exhibited the most sensitivity to filtration rate and sand size. The filters produced effluent with turbidities of 0.1-0.5 NTU, SS concentrations of 3-6mg/l in the fine sand and 6-9mg/l in the coarse sand. Effluent BOD(5) and COD concentrations were mostly in the 0.8-2.6 and 15-34mg/l range, respectively.     

Biological nitrate removal from wastewater of a metal-finishing industry

An upflow packed bed reactor at laboratory scale has been operated for a continuous period of 5 months to investigate the technical feasibility of biological nitrate removal applied to the effluent of the coagulation-sedimentation wastewater of a metal-finishing industry. The reactor was fed with industrial wastewater in a five-fold dilution to reproduce the global spill in the factory (20/80, industrial wastewater/domestic wastewater) with a concentration of nitrate between 141 and 210 gNO(3)-N/m(3). Methanol was added as a carbon source for denitrification. Inlet flow rate was progressively increased from 9 to 40 L/day (nitrogen input load from 45 to 250 gNO(3)-N/(m(3)h)). The highest observed denitrification rate was 135 gNO(3)-N/(m(3)h) at a nitrate load of 250 gNO(3)-N/(m(3)h), and removal efficiencies higher than 90% were obtained for loads up to 100 gNO(3)-N/(m(3)h). A mass relation between COD consumed and NO(3)-N removed around 3.31 was observed. Better results were achieved in a previous stage using tap water with nitrate added as a sole pollutant as a synthetic feed (critical load of 130 gNO(3)-N/(m(3)h) and denitrification rate of 200 gNO(3)-N/(m(3)h) at a nitrate load of 250 gNO(3)-N/(m(3)h)). This fact could indicate that the chemical composition of the industrial source hinders to some extent the performance of the biological process. Whatever case, results demonstrated the viability of the denitrification process for the global industrial wastewater. A simple model based on Monod kinetics for substrate consumption, and constant biomass concentration was applied to model the industrial wastewater treatment, and a reasonably good fitting was obtained.     

Landfill leachate treatment with a novel process: anaerobic ammonium oxidation (Anammox) combined with soil infiltration system

A novel combined process was proposed to treat municipal landfill leachate with high concentrations of ammonium and organics. This process consisted of a partial nitritation reactor (PNR), an anaerobic ammonium oxidation (Anammox) reactor (AR) and two underground soil infiltration systems (USIS-1 and USIS-2). Based on the optimum operating conditions obtained from batch tests of individual unit, the combined process was continuously operated on a bench scale for 166 days. Partial nitritation was performed in a fixed bio-film reactor (PNR, working volume=12 L). Ammonium nitrogen-loading rate (Nv) and DO were combined to monitor partial nitritation, and at T=30+/-1 degrees C, Nv=0.27-1.2 kg/(m3.d), DO=0.8-2.3 mg/L, the ratios of nitrite nitrogen (NO2--N) to ammonium nitrogen (NH4+-N) were successfully kept close to 1.0-1.3 in the effluent. Nitrate nitrogen (NO3--N) less than 43 mg/L was observed. The effluent of PNR was ideally suited as influent of AR. Sixty-nine percent CODcr from the raw leachate was degraded in the PNR. Anammox was carried out in a fixed bio-film reactor (AR, working volume=36 L). At T=30+/-1 degrees C, Nv=0.06-0.11 kg/(m3.d), about 60% NH4+-N and 64% NO2--N in the influent of AR were simultaneously removed. Inhibition of high-strength NO2--N (up to 1011 mg/L) should be responsible for the low removal rate of nitrogen. About 35% aquatic humic substance (AHS) was degraded in the AR. With the same working volume (200 L), USIS-1 and USIS-2 were alternately performed to treat the effluent from AR at one cycle of about 30 days. At hydraulic loading rate (HLR)=0.02-0.04 m3/m3.d, pollutant loading rates (PLR)=NH4+-N相似文献   

Nitritation and denitritation of ammonium-rich wastewater using fluidized-bed biofilm reactors

Fluidized-bed biofilm nitritation and denitritation reactors (FBBNR and FBBDR) were operated to eliminate the high concentrations of nitrogen by nitritation and denitritation process. The dissolved oxygen (DO) concentration was varied from 1.5 to 2.5 g/m(3) at the top of the reactor throughout the experiment. NH(4)-N conversion and NO(2)-N accumulation in the nitritation reactor effluent was over 90 and 65%, respectively. The average NH(4)-N removal efficiency was 99.2 and 90.1% at the NLR of 0.9 and 1.2 kg NH(4)-N/m(3)day, respectively. Increasing the NLR from 1.1 to 1.2 kg NH(4)-N/m(3)day decreased the NH(4)-N elimination approximately two-fold while NH(4)-N conversion to NO(2)-N differences were negligible. The NO(2)-N/NO(x)-N ratios corresponded to 0.74, 0.73, 0.72, and 0.69, respectively, indicating the occurrence of partial nitrification. An average free ammonia concentration in the FBBNR was high enough to inhibit nitrite oxidizers selectively, and it seems to be a determining factor for NO(2)-N accumulation in the process. In the FBBDR, the NO(x)-N (NO(2)-N+NO(3)-N) concentrations supplied were between 227 and 330 mg N/l (NLR was between 0.08 and 0.4 kg/m(3)day) and the influent flow was increased as long as the total nitrogen removal was close to 90%. The NO(2)-N and NO(3)-N concentrations in the effluent were 3.0 and 0.9 mg/l at 0.08 kg/m(3)day loading rate. About 98% removal of NO(x)-N was achieved at the lowest NLR in the FBBDR. The FBBDR exhibited high nitrogen removal up to the NLR of 0.25 kg/m(3)day. The NO(x)-N effluent concentration never exceeded 15 mg/l. The total nitrogen removal efficiency in the FBBRs was higher than 93% at 21+/-1 degrees C.     

Tertiary treatment of textile wastewater with combined media biological aerated filter (CMBAF) at different hydraulic loadings and dissolved oxygen concentrations

An up-flow biological aerated filter packed with two layers media was employed for tertiary treatment of textile wastewater secondary effluent. Under steady state conditions, good performance of the reactor was achieved and the average COD, NH(4)(+)-N and total nitrogen (TN) in the effluent were 31, 2 and 8mg/L, respectively. For a fixed dissolved oxygen (DO) concentration, an increase of hydraulic loading resulted in a decrease in substrate removal. With the increase of hydraulic loadings from 0.13 to 0.78m(3)/(m(2)h), the removal efficiencies of COD, NH(4)(+)-N and TN all decreased, which dropped from 52 to 38%, from 90 to 68% and from 45 to 33%, respectively. In addition, the results also confirmed that the increase of COD and NH(4)(+)-N removal efficiencies resulted from the increase of DO concentrations, but this variation trend was not observed for TN removal. With the increase of DO concentrations from 2.4 to 6.1mg/L, the removal efficiencies of COD and NH(4)(+)-N were 39-53% and 64-88%, whenas TN removal efficiencies increased from 39 to 42% and then dropped to 35%.     

Magnetic gamma-Fe(2)O(3) nanoparticles coated with poly-l-cysteine for chelation of As(III), Cu(II), Cd(II), Ni(II), Pb(II) and Zn(II)

An anaerobic attached-growth bioreactor (AAGBR) of 3.52 L was operated for 510 days to treat sulfide-laden organic wastewater where nitrate and nitrite were introduced as electron acceptors. When the influent sulfide was kept at 200mg S(2-)-S/L and organic carbon was increased from 20 to 33.6 mg C/L, and the hydraulic retention time decreased from 41.4 to 2.67 h, the removal rates of sulfide and organic carbon reached 99.9% and 91.8% at the loading rates of 1800 mg S(2-)-S/(Ld) and 302.4 mg C/(Ld), respectively. Simultaneously, the introduced electron acceptors of nitrate and nitrite were, respectively, removed by 99.9% and 99.9% at the loading rates of 472.5 mg NO(3)(-)-N/(Ld) and 180 mg NO(2)(-)-N/(Ld). Inside the AAGBR, both autotrophic and heterotrophic denitrification processes were noted to take place. When the influent organic carbon was increased from 20 to 33.6 mg C/L, the nitrate and nitrite consumed for heterotrophic denitrification accounted for 27.3% and 48.5%, respectively. This simultaneous autotrophic and heterotrophic desulfurization-denitrification process has provided a demonstration of the possibility to eliminate sulfide and organic carbon with the presence of nitrate and nitrite.     

Selective inhibition of nitrite oxidation by chlorate dosing in aerobic granules

Partial nitrification was successfully achieved with addition of 5mM KClO(3) in the aerobic granules system. Batch tests demonstrated that KClO(3) selectively inhibited nitrite-oxidizing bacteria (NOB) but not ammonia-oxidizing bacteria (AOB). During stable partial nitrification, the influent pH was kept at 7.8-8.2, while the DO and temperature were not controlled in the SBR. When the NH(4)-N and COD levels were kept at 100mg/l and 400mg/l in the influent, the NH(4)-N and COD removal efficiencies reached 98.93% and 78.65%, respectively. The NO(2)-N accounted for 92.95% of the NO(χ)-N (NO(2)-N+NO(3)-N) in the effluent. Furthermore, about 90% of the chlorate was reduced to nontoxic chloride, thus it would not cause environmental problem. SEM showed that the main composition of the aerobic granules was bacilli and coccus bacteria. FISH analysis revealed that AOB became the dominant nitrifying bacteria, whereas NOB were detected only in low abundance. Chlorate could be used to control the development and maintenance of aerobic granules sludge for partial nitrification.     

Physico-chemical treatments for removal of recalcitrant contaminants from landfill leachate

In this paper, the technical applicability and treatment performance of physico-chemical techniques (individual and/or combined) for landfill leachate are reviewed. A particular focus is given to coagulation-flocculation, chemical precipitation, ammonium stripping, membrane filtration and adsorption. The advantages and limitations of various techniques are evaluated. Their operating conditions such as pH, dose required, characteristics of leachate in terms of chemical oxygen demand (COD) and NH3-N concentration and treatment efficiency are compared. It is evident from the survey of 118 papers (1983-2005) that none of the individual physico-chemical techniques is universally applicable or highly effective for the removal of recalcitrant compounds from stabilized leachate. Among the treatments reviewed in this article, adsorption, membrane filtration and chemical precipitation are the most frequently applied and studied worldwide. Both activated carbon adsorption and nanofiltration are effective for over 95% COD removal with COD concentrations ranging from 5690 to 17,000 mg/L. About 98% removal of NH3-N with an initial concentration ranging from 3260 to 5618 mg/L has been achieved using struvite precipitation. A combination of physico-chemical and biological treatments has demonstrated its effectiveness for the treatment of stabilized leachate. Almost complete removal of COD and NH3-N has been accomplished by a combination of reverse osmosis (RO) and an upflow anaerobic sludge blanket (UASB) with an initial COD concentration of 35,000 mg/L and NH3-N concentration of 1600 mg/L and/or RO and activated sludge with an initial COD concentration of 6440 mg/L and NH3-N concentration of 1153 mg/L. It is important to note that the selection of the most suitable treatment method for landfill leachate depends on the characteristics of landfill leachate, technical applicability and constraints, effluent discharge alternatives, cost-effectiveness, regulatory requirements and environmental impact.     

超滤膜生物反应器处理生活污水的试验研究

用外压一体化中空纤维超滤膜生物反应器（ＵＭＢＲ）进行了处理生活污水的试验．结果表明,当水力停留时间（ＨＲＴ）为５ｈ、膜通量在４４２～１１０Ｌ／ｈ时,ＵＭＢＲ对生活污水中ＣＯＤ、浊度、ＳＳ的去除率分别可达９０％、９８％、１００％,出水ＣＯＤ＜６０ｍｇ／Ｌ、浊度＜３、ＳＳ为０,污泥质量浓度ρＭＬＳＳ、污泥负荷Ｆｒ、反应器容积负荷ＦＷ分别为６２ｋｇ／ｍ３、０４６ｋｇ／（ｋｇ·ｄ）、１８２ｋｇ／（ｍ３·ｄ）．初步探讨了超滤膜的堵塞机理,通过杀菌清洗可使超滤膜通透能力恢复到新膜的９７％以上．ＵＭＢＲ出水浊度低,水质稳定,宜于回用     

Chemical denitrification of water by zero-valent magnesium powder

A laboratory-scale study was conducted in batch mode to investigate the feasibility of using zero-valent magnesium (Mg(0)), for removal of nitrate from aqueous solution. Reaction pH, dose of Mg(0), initial nitrate concentration and temperature were considered variable parameters during the study. Strong acidic condition enhanced nitrate reduction and in absence of external proton addition, reaction pH increased rapidly above ten and insignificant nitrate removal (7-16%) was achieved. At Mg(0):NO(3)(-)-N molar ratio of 5.8 and controlled reaction pH of 2, 84% denitrification efficiency was achieved (initial NO(3)(-)-N 50 mg/L) under ambient temperature and pressure and total nitrogen removal was 70% with 3.2% and 10% conversion of initial NO(3)(-)-N to NO(2)(-)-N and NH(4)(+)-N, respectively. The reaction was first order with respect to nitrate concentration. Nitrate removal rate decreased with solution pH and increased linearly with Mg(0) dose. Nitrate removal was coupled with 96-100% removal of dissolved oxygen and 85-90% generation of soluble Mg(2+) ion. An activation energy (E(a)) of nitrate reduction over the temperature range of 10-50 degrees C was observed as 17.7 kJ mol(-1).     

Inoculation of a submerged filter for biological denitrification of nitrate polluted groundwater: a comparative study

Activated sludge from a wastewater treatment plant and pure culture of Hydrogenophaga pseudoflava were utilized for the development of a denitrifying biofilm in a submerged filter in order to remove nitrate from polluted groundwater. Nitrate removal efficiency, nitrite accumulation, turbidity, COD and faecal indicators persistence in the treated water were determined at different superficial hydraulic loading (10, 20 and 30 m(3)/m(2) d) and superficial nitrate loading rates (1, 2, 3, 6 and 9 Kg NO(3)(-)/m(2) d) in the submerged filter. The application of H. pseudoflava as inocula allowed better results in terms of system stability, higher superficial hydraulic loading and superficial nitrate loading rates (30 m(3)/m(2)d and 9 kg NO(3)(-) /m(2) d, respectively). These values improve those obtained when the system was inoculated with activated sludge. In addition, the pure microbial inocula improved design parameters and running of the process due to its biofilm homogeneity, obtaining treated water with better characteristics to its final use as drinking water than that obtained with an activated sludge inocula.     

A/O MBR处理城市污水回用的中试研究

采用中试规模(36 m3/d)的缺氧-好氧膜生物反应器(A/O MBR)对城市污水处理回用进行了试验研究.试验结果表明,该工艺处理效果优良,系统对COD、氨氮、浊度、细菌的平均去除率分别为94%,98.3%,99.6%,lg6,出水浓度分别为18 mg/L,0.65 mg/L,0.06 NTU,4个/mL.出水水质优于城市杂用水水质标准(GB/T 18920-2002).该系统具有较强的抗冲击负荷能力.     

Development of empirical models for performance evaluation of UASB reactors treating poultry manure wastewater under different operational conditions

A nonlinear modeling study was carried out to evaluate the performance of UASB reactors treating poultry manure wastewater under different organic and hydraulic loading conditions. Two identical pilot scale up-flow anaerobic sludge blanket (UASB) reactors (15.7 L) were run at mesophilic conditions (30-35 degrees C) in a temperature-controlled environment with three hydraulic retention times (theta) of 15.7, 12 and 8.0 days. Imposed volumetric organic loading rates (L(V)) ranged from 0.65 to 4.257 kg COD/(m(3) day). The pH of the feed varied between 6.68 and 7.82. The hydraulic loading rates (L(H)) were controlled between 0.105 and 0.21 m(3)/(m(2)day). The daily biogas production rates ranged between 4.2 and 29.4 L/day. High volumetric COD removal rates (R(V)) ranging from 0.546 to 3.779 kg COD(removed)/(m(3)day) were achieved. On the basis of experimental results, two empirical models having a satisfactory correlation coefficient of about 0.9954 and 0.9416 were developed to predict daily biogas production (Q(g)) and effluent COD concentration (S(e)), respectively. Findings of this modeling study showed that optimal COD removals ranging from 86.3% to 90.6% were predicted with HRTs of 7.9, 9.5, 11.2, 12.6, 13.7 and 14.3 days, and L(V) of 1.27, 1.58, 1.78, 1.99, 2.20 and 2.45 kg COD/(m(3)day) for the corresponding influent substrate concentrations (S(i)) of 10,000, 15,000, 20,000, 25,000, 30,000 and 35,000 mg/L, respectively.     

The performance of BAF using natural zeolite as filter media under conditions of low temperature and ammonium shock load

Natural zeolite and expanded clay were used as filter media for biological aerated filter (BAF) to treat municipal wastewater in parallel in whole three test stages. The stage one test results revealed that zeolite BAF and expanded clay BAF have COD and NH(3)-N removals in the range of 84.63-93.11%, 85.74-96.26%, 82.34-93.71%, and 85.06-93.2%, respectively, under the conditions of water temperature of 20-25 degrees C and hydraulic load of 2-3m(3)/(m(2)h). At the following stage two, the influent NH(3)-N concentration was increased to about double value of the stage one, and it was investigated that the effluent NH(3)-N of expanded clay BAF increased significantly and then gradually restored to normal condition in 2 weeks, while the effluent NH(3)-N of zeolite BAF kept stable. At stage three, the low reactor temperature has also different effects on these two BAFs, under conditions of water temperature of 7-10 degrees C, hydraulic load of 2-3m(3)/(m(2)h), zeolite BAF and expanded clay BAF have COD and NH(3)-N removals in the range of 74.5-88.47% (average of 81.57%), 71.73-88.49% (average of 81.06%), 71.91-87.76% (average of 80.49%), and 38.41-77.17% (average of 65.42%), respectively. Three stages test results indicated that the zeolite BAF has a stronger adaptability to NH(3)-N shock load and low temperature compared to expanded clay BAF. In addition, the detection of the amounts of heterobacteria and nitrobacteria of two biological aerated filters in three stages also showed the zeolite filter media was more suitable to the attached growth of nitrobacteria, which is helpful to the improvement of nitrification performance in zeolite BAF.     

Trimethylamine (TMA) biofiltration and transformation in biofilters

Bioremoval of trimethylamine (TMA) in two three-stage biofilters packed with compost (A) and sludge (B), respectively, was investigated. Both biofilters were operated with an influent TMA concentration of 19.2-57.2mgm(-3) for 67 days. Results showed that all of the inlet TMA could be removed by both biofilters. However, removal efficiency and transformation of TMA in each section of both biofilters was different. In the Introduction section, TMA removal efficiency and maximum elimination capacity of the compost medium were greater than those of sludge medium under higher inlet TMA concentration. In comparison with biofilter A, considerably higher NH(3) concentrations in effluent of all three sections in biofilter B were observed after day 19. Although, NO(2)(-)-N concentration in each section of biofilter A was relatively lower, NO(3)(-)-N content in each section of biofilter A increased after day 26, especially in the Materials and method section which increased remarkably due to a lesser amount of TMA and higher ammonia oxidation and nitrification in compost medium. In contrast, neither NO(2)(-)-N nor NO(3)(-)-N were detected in either section of biofilter B at any time throughout the course of the experiment. The cumulative results indicated that compost is more favorable for the growth of TMA-degrading and nitrifying bacteria as compared to the sludge and could be a highly suitable packing material for biodegradation and transformation of TMA.     

水热法制备氧化铬及其常温低浓度一氧化氮催化性能

以十六烷基三甲基溴化铵(CTAB)为模板剂, 氨水为沉淀剂, 通过水热法并焙烧处理合成氧化铬催化剂。采用X射线衍射分析(XRD)、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)和透射电镜(TEM)等技术对催化剂的物化性质进行了表征, 并考察常温不同NO初始浓度下氧化铬催化剂的NO氧化性能。结果表明: 在空速为60000 mL/(g·h)和NO浓度为1×10^-6的条件下, 100℃水热温度制备的Cr-100催化剂表现出最优的性能, 常温下NO消除率高达90%以上并保持120 h, 其优异的常温催化性能与催化剂表面较高的Cr⁶⁺/Cr³⁺摩尔比有关。研究结果表明: 催化剂的失活主要是由于硝酸根在催化剂表面的累积而导致催化剂活性中心被覆盖, 低浓度下能减缓硝酸根的积累。     

Degradation of formaldehyde in anaerobic sequencing batch biofilm reactor (ASBBR)

The present study evaluated the degradation of formaldehyde in a bench-scale anaerobic sequencing batch reactor, which contained biomass immobilized in polyurethane foam matrices. The reactor was operated for 212 days at 35 degrees C with 8h sequential cycles, under different affluent formaldehyde concentrations ranging from 31.6 to 1104.4 mg/L (formaldehyde loading rates from 0.08 to 2.78 kg/m(3)day). The results indicate excellent reactor stability and over 99% efficiency in formaldehyde removal, with average effluent formaldehyde concentration of 3.6+/-1.7 mg/L. Formaldehyde degradation rates increased from 204.9 to 698.3mg/Lh as the initial concentration of formaldehyde was increased from around 100 to around 1100 mg/L. However, accumulation of organic matter was observed in the effluent (chemical oxygen demand (COD) values above 500 mg/L) due to the presence of non-degraded organic acids, especially acetic and propionic acids. This observation poses an important question regarding the anaerobic route of formaldehyde degradation, which might differ substantially from that reported in the literature. The anaerobic degradation pathway can be associated with the formation of long-chain oligomers from formaldehyde. Such long- or short-chain polymers are probably the precursors of organic acid formation by means of acidogenic anaerobic microorganisms.     

膜生物反应器脱氮除磷工艺处理城市污水的工程应用

为强化城市污水脱氮除磷,研发了厌氧/缺氧/好氧/缺氧-膜生物反应器(A2/O/A-MBR)新工艺,并建设了设计处理规模为2万m3/d实际工程.对该工程的长期监测表明,出水C()D、TN、NH4+-N和TP的平均浓度分别为20.6、6.67、1.05、0.19 mg/L,优于《城镇污水处理厂污染物排放标准》中的一级A标准...     

PRELIMINARY PERFORMANCE TESTS OF A PULSED JET PLEATED PAPER CARTRIDGE FILTER SYSTEM

A pulsed jet pleated paper cartridge filter system was tested for particle removal efficiency and operating stability using agricultural limestone as the test dust. The test system consisted of 6 pleated paper filter units arranged in parallel, each unit having an effective filtration area of 18.1 square meters. The system was operated at constant pressure drops of 6.25, 7.50 and 8.75 kPa (2.5, 3.0 and 3.5 inches of water), with face velocities of 0.78 to 1.04 m/ min (2.5 to 3.4 feet per minute) and dust loadings ranging from 0.5 g/ m to 2.5 g/ m³. Penetration through the media appeared to be relatively independent of dust loading, and efficiencies were in the 99.95 + % range. Slightly lower efficiencies were found for particles having diameters of 0.3 to 1.0 micrometers. A measure of the redeposition of dust pulsed from the filter was required to describe the effects on the pulse rate caused by changes in system flow and pulsing set point. Increased redeposition was found to occur with increasing flow rate, causing an increase in the pulse rate required to maintain operation of the system at a pulsing set point. Overall, the reverse pulse jet pleated paper cartridge filter system displayed extremely high particle removal efficiency in a compact unit that operated with low differential pressure.     

Degradation of recalcitrant compounds from stabilized landfill leachate using a combination of ozone-GAC adsorption treatment

Laboratory experiments were undertaken to investigate the treatment performances of ozonation alone and/or its combination with granular activated carbon (GAC) adsorption for raw leachate from the NENT landfill (in Hong Kong). To improve its removal of recalcitrant contaminants from the leachate, the surface of GAC was oxidized with ozone prior to treatment. With respect to ozone dose and pH, the removal of COD and/or NH(3)-N from ozonation alone and combined ozone-GAC adsorption were evaluated and compared to those of other physico-chemical treatments in some reported studies. The removal mechanism of recalcitrant compounds by ozone-GAC adsorption treatment was presented. Among the various treatments studied, the combination of ozone-GAC adsorption using ozone-modified GAC had the highest removal for COD (86%) and/or NH(3)-N (92%) compared to ozonation alone (COD: 35%; NH(3)-N: 50%) at the same initial COD and/or NH(3)-N concentrations of 8000 and 2620 mg/L, respectively. Although the integrated treatment was more effective than ozonation alone for treating stabilized leachate, the results suggested that it could not generate treated effluent that complied with the COD limit of lower than 200 mg/L and the NH(3)-N discharge standard of less than 5 mg/L. Therefore, further biological treatments to complement the degradation of the leachate are still required to meet the environmental legislation.