亚硝化—厌氧氨氧化处理猪场废水研究

猪场废水COD浓度高、氨氮浓度高、悬浮物浓度高，已成为农村面源污染的主要来源，并严重威胁到农村饮用水安全。猪场废水氨氮浓度高、处理难度大，如何采用经济高效的方法，去除氨氮使其达到排放标准，一直是猪场废水处理中面临的重要难题。 厌氧氨氧化是近年受到国内外水处理研究者广泛关注的新型生物脱氮技术，具有不需要外加有机碳源、节省供氧量、降低能耗等优点。虽然国内外研究者对厌氧氨氧化过程的脱氮机理、厌氧氨氧化菌的生理生化特性等进行了多方面的研究，但已有的报道大多以模拟废水为研究对象，以猪场废水为研究对象的报道，在国内外文献中极少有报导。 本论文以猪场废水为主要研究对象，考察了猪场废水的亚硝化过程、厌氧氨氧化的启动过程，并对亚硝化和厌氧氨氧化联合用于猪场废水脱氮进行了探索。 1．论文首先研究了猪场废水的亚硝化过程，考察了废水水质和主要运行条件对亚硝化过程的影响。实验表明：（1）亚硝化阶段反应时间为8到10h时，出水中氨氮和亚硝酸盐浓度比可达到1：1～1：1.23，满足厌氧氨氧化反应对二者比例的要求；达到前述要求时，氨氮去除率达到58.3～65.6 %，亚硝化率在整个过程均保持在97 %以上，COD去除率在59.2～68.6 %；（2）曝气量（溶解氧）对亚硝化过程影响显著，随着曝气量增大，达到厌氧氨氧化要求的氨氮与亚硝酸盐氮浓度比例所需水力停留时间τ越短，pH出现明显下降的时间越短；（3）τ对应的pH在7.8～8.1之间，无需进行pH调节即可满足厌氧氨氧化反应对pH的要求；（4）氨氮和COD降解过程遵循一级反应动力学，氨氮和COD降解的速率常数分别为0.0656～0.0724 1/h和0.0491～0.0664 1/h。 2．在进行亚硝化过程研究的同时，以模拟废水为试验对象，进行厌氧氨氧化启动研究。以反硝化污泥和养殖厂储水池厌氧底泥的混合污泥作为接种污泥，历时大约100天，培育出具有厌氧氨氧化活性的污泥，氨氮和亚硝酸盐氮最高进水浓度分别为223.8 mg/L和171.4 mg/L，去除率最高分别达48%和41.5%，此时二者消耗比例为1.33：1。 3．在猪场废水的亚硝化研究完成和厌氧氨氧化过程初步启动成功后，在模拟废水中逐步加入猪场废水的亚硝化处理出水，逐步实现亚硝化和厌氧氨氧化的组合。亚硝化出水添加到厌氧反应器后，厌氧氨氧化反应仍可继续进行，且去除效率逐步提高。研究发现添加的亚硝化出水中携带的亚硝化细菌在厌氧氨氧化菌膜外层生长并累积，增加了厌氧氨氧化反应基质的传质阻力，妨碍了厌氧氨氧化效率的提高。 4．亚硝化－厌氧氨氧化实际工程应用探索中，生物接触氧化池可在有效去除废水中的有机物的同时实现亚硝化，出水中氨氮和亚硝酸盐比例平均为1.10，可满足后续厌氧氨氧化的要求；在适宜的进水浓度和温度下，ABR池出现了厌氧氨氧化启动的迹象；研究同时发现，水质的波动和气温的变化是工程中影响厌氧氨氧化菌活性的重要因素。 论文的主要创新点在于：（1）以猪场废水为研究对象，以实现厌氧氨氧化为目标，对亚硝化过程进行了比较详细的考察，获得了亚硝化出水满足厌氧氨氧化要求的工艺条件，通过对其COD和氨氮降解过程的考察，得出亚硝化阶段COD降解和氨氮去除的动力学模型；（2）对亚硝化－厌氧氨氧化处理猪场废水进行了探索，确立了影响其污染物去除率稳定的重要因素。 论文的上述研究成果，为厌氧氨氧化技术的实用性研究提供理论依据。 Piggery wastewater, which is characterized by high concentration of COD、ammonium and suspend substance, has become a most important source of non-point source pollution and also severely threats drinking water security in rural area. How to discharge piggery wastewater with the ammonium concentration meeting standard by economical and effective method? This is the most urgent problem in piggery wastewater treatment. As a new biological nitrogen removal technology, Anammox process has been paid more and more attention by researchers all over the world. Anammox has advantages of no need of organic carbon addition, low oxygen consumption and energy consumption. Plenty of investigations have been carried out to the mechanism, physiological and biochemical characteristic of bacteria about Anammox. Most of researches focused on synthetic wastewater, there is rare report about its application in piggery wastewater. In this paper，experimental studies were performed to investigate Sharon process in treatment of piggery wastewater，the start up process of Annammox using synthetic wastewater were studied, the feasibility of applying Sharon-Anammox process in the nitrogen removal of piggery wastewater was evaluated. 1. Sharon process of piggery wastewater was firstly investigated to analyze the effects of water quality and main running parameters, which meet the NH4+-N to NO2--N ratio requirement of successive Anammox. Results showed: (1)During Sharon Process，after 8～10 hours’ reaction the NH4+-N to NO2--N ratio in effluent reached 1:1.0～1:1.23, when the removal percentage of NH4+-N was 58.3～65.6 %, a semi-nitration rate of above 97 % was achieved during the process; meanwhile 59.2～68.6 % of the COD was also removed. (2)The aeration rate（oxygen） had obvious effect on the hydraulic retention time(τ) which met the NH4+-N to NO2--N ratio requirement of Anammox. As aeration rate increased, the hydraulic retention time(τ) was shortened. (3) The pH corresponding to τ was between 7.8 and 8.1, thus it needed no artificial adjustment. (4) The reduction of ammonia and COD followed the first-order reaction kinetics. The velocity constants of ammonia and COD were 0.0656～0.0724 1/h and 0.0491～0.0664 1/h, respectively. 2. The startup of Anammox process using the artificial wastewater was performed simultaneously with Sharon. The aim was to investigate the running parameters of Anammox and make foundation for the combination stage. By using the mixture of denitrifying sludge and anaerobic sludge in tank of the breeding factory, sludge of Anammox activity was cultivated in UASB after 100 days. The removal percentage of NH4+-N and NO2-N were up to 48% and 41.5%, respectively, when the NH4+-N and NO2-N influent concentration were 223.8 mg/L and 171.4 mg/L, respectively, the NH4+-N and NO2-N removal rate was 1.33:1. 3. After investigation of Sharon and startup of Anammox, effluent of Sharon process was added into the synthetic wastewater to combine Sharon and Anammox step by step. It took some time after the addition of Sharon effluent that Anammox reaction continued and the removal rate kept increasing. It indicated that nitrifying bacteria were carried by the Sharon effluent cumulated in the outer layer of Anammox. This enhanced transfer resistance of Anammox reaction and the increasing removal rate was restrained. 4. In the bio-contact oxidation pond of practical project, Sharon process were carried out successfully and organic compounds were removed effectively. An average NO2-N/ NH4+-N rate of 1:1.0 was achieved in the effluent, which met the requirement of successive Anammox. Under condition of suitable influent concentration and temperature, there was evidence that Anammox could start up in ABR. The variety of wastewater and temperature had great affects on Anammox activity in practical engineering. Innovation of this paper: (1) The Sharon process for treating piggery wastewater was discussed in details. Technological parameters that met requirement of Anammox were obtained. The dynamic models of COD and ammonium removal in the process were educed. (2) Sharon-Ananmmox for treatment of piggery wastewater was investigated, and the primary influencing factors was studied. This paper could be a theoretical consult for research of Anammox utility.

猪场废水短程硝化反硝化-厌氧氨氧化脱氮研究

畜禽废水是农村水环境污染的主要来源之一，其处理的难点在于脱氮。传统生物脱氮法具有能耗高、需大量外加碳源等缺点，开发低成本、高效率的新型生物脱氮技术具有重要意义。 本研究将短程硝化反硝化和厌氧氨氧化两种脱氮新技术结合，让前者为后者创造去除可降解COD、降低总氮负荷、调整pH、调整氨氮和亚硝酸盐氮浓度比例等进水条件，而后者可在无需外加碳源的条件下进一步脱氮，二者结合可成为高氨氮、低C/N废水脱氮的新途径。 试验以低碳氮比猪场废水为研究对象，首先进行了短程硝化反硝化预处理研究，同时启动并运行调控厌氧氨氧化反应器，最后以经过短程硝化反硝化预处理的猪场废水为进水，进行厌氧氨氧化脱氮考察。实验表明：（1）短程硝化反硝化作为厌氧氨氧化的预处理工序是可行的。猪场废水通过短程硝化反硝化，可以达到基本去除可生化COD、部分脱氮、控制出水氨氮和亚硝酸盐氮浓度之比在1︰1左右、pH在7.5～8.0的目的， COD和总氮平均去除率分别为64.3%、49.1%,出水可达到厌氧氨氧化反应的进水要求。（2）采用模拟废水启动厌氧氨氧化反应器，经过5个月左右的运行调控，反应器启动成功并稳定运行，最高总氮去除率为87.1%，总氮容积去除率最高达到0.14kg/m3.d；整个稳定阶段，氨氮、亚硝酸盐氮、硝酸盐氮的变化量之比为1︰1.21︰0.33。（3）经过短程硝化反硝化预处理的猪场废水厌氧氨氧化脱氮效果稳定，氨氮、亚硝酸盐氮、总氮、COD的平均去除率分别为93.0%、99.4%、84.6%、18.1%，处理效果与模拟废水处理系统相比无明显变化。（4）经过短程硝化反硝化预处理后，猪场废水中残留有机物成分在厌氧氨氧化反应过程中无显著变化，主要为酯类和烷烃类物质；残留有机物对厌氧氨氧化效果无明显影响。（5）采用PCR技术进行特殊功能菌种检测，结果表明模拟废水处理系统和猪场废水处理系统的菌群中均含有厌氧氨氧化菌和好氧硝化菌；通过blast比对，厌氧氨氧化菌扩增序列与未培养的Planctomycetales菌和Candidatus Brocadia fulgida菌16S rRNA部分序列相似性分别为95％、90%。（6）MPN法菌种计数结果显示，模拟废水处理系统和猪场废水处理系统的菌群中均含有硝化细菌、亚硝化细菌和少量反硝化菌，实验条件下的微生物系统是一个厌氧氨氧化菌与好氧硝化菌、反硝化菌共存的系统。 Poultry wastewater is one of the main source of water pollution in rural areas，and nitrogen removal is the most difficult part in treating poultry wastewater. There are some disadvantages in traditional nitrogen removal, such as high energy consumption and more additional organic carbon. It is important to develop ecolomical and efficient technologyies. Shortcut nitricfication/denitrification, as a pretreatment process, was combined with Anammox in this research, so that part of total nitrogen and most degradable COD could be removed by the former, and further nitrogen removal could be implemented by the latter. The combination of the two technologies was a new approach to treat wastewater with high ammonium and low C/N. Piggery wastewater with low C/N was treated in lab-scale experiment. Firstly, shortcut nitrification/denitrification was investigated, and Anammox reactor was started up successfully at the same time. Then piggery wastewater after pretreatment was treated by Anammox. The results showed :(1) It was feasible to take nitrification/denitrification as the pretreatment process of Anammox. By using this process, part of total nitrogen and COD were removed, the ratio of ammonium and nitrite reached around 1︰1 and the pH was about 7.8, which were favorable for Anammox. The average removal percentage of COD and total nitrogen were about 64.3% and 49.1%, respectively. (2) Simulated wastewater was used to start up Anammox reactor. The reactor was started up successfully within 5 months and stable performance was achieved. The highest nitrogen removal reached 87.1% and the biggest volumetric total nitrogen removal rate reached 0.14kg/m3.d. The average ratio of ammonium, nitrite and nitrate was 1:1.21:0.33. (3)Taking the effluent of shortcut nitrification/denitrification as the influent, the nitrogen removal efficiency of Anammox was stable, and the the average removal percentage of ammonium, nitrite, total nitrogen and COD were 93.0%, 99.4% , 84.6% and 18.1%, respectively, which had little difference with that by using simulated wastewater..(4) After pretreatment, the residual organic carbon in piggery wastewater showed no obvious change during the Anammox process, and the main organic compounds were saturated hydrocarbon and ester, which had no obvious negative effect on Anammox process.(5) By PCR technology, the existence of Anammox bacteria was confirmed and the aerobic nitrifying bacteria was found to coexist as well. The result of blast showed that the identities of Anammox bacterium to part of 16S rRNA sequence of uncultured Planctomycetales bacterium and Candidatus Brocadia fulgida bacterium were 95% and 90%, respectively.（6）By MPN method, nitrite oxidizer, ammonium oxidizer and denitrification bacteria were detected in both simulated and piggery wastewater treatment system of Anammox, and the microorganism system was composed of Anammox bacteria，aerobic bacteria and denitrification bacteria together.

Coagulation removal of melanoidins from biologically treated molasses wastewater using ferric chloride

The pigments (melanoidins) in molasses wastewater are refractory to conventional biological treatment. Ferric chloride was used as coagulant to remove color and chemical oxygen demand (COD) from molasses effluent. Using jar test procedure, main operating conditions such as pH and coagulant dosage were investigated. Under the optimum conditions, up to 86% and 96% of COD and color removal efficiencies were achieved. Residual turbidity in supernatant was less than 5 NTU and Fe3+ concentration was negligible because of effective destabilization and subsequent sedimentation. The results of high performance size exclusion chromatography (HPSEC) show that low molecular weight (MW) fraction of melanoidins is more reactive than high MW fraction and increase in the concentration of the lowest MW organic group is related to the capacity of charge neutralization. Aggregate size measurement reveals the size effect on the settleability of flocs formed, with larger flocs settling more rapidly. Charge neutralization and co-precipitation are proposed as predominant coagulation mechanism under the optimum conditions. (C) 2009 Elsevier B.V. All rights reserved.

Polishing Treatment of Molasses Wastewater with Iron Salts: the Role of Counter-ions

The effect of counter-ions on the coagulation of biologically treated molasses wastewater using iron-based coagulants was investigated. Parameters such as removals of chemical oxygen demand (COD) and color, and residual turbidity, were measured to evaluate coagulation performance. Experimental results showed that ferric chloride and ferric nitrate were more effective than ferric sulfate at optimal dosages, achieving 89 to 90% and 98 to 99% of COD and color removals, respectively, with residual turbidity of less than 5 NTU. High-performance size exclusion chromatography (HPSEC) results revealed differences in the removal of the molecular weight fraction of organic compounds using iron salts. Scanning electron microscopy (SEM) showed randomly formed coagulated flocs characterized with irregular, sheet-like shapes. Nitrate and chloride counter-ions had similar effects on coagulation performance compared to sulfate. Both FeCl3 and Fe(NO3)(3) yielded better results than Fe(SO4)(2) under underdosed and optimum dosage conditions. Coagulation efficiency was less adversely affected in the overdosed regions, however, if sulfate rather than chloride or nitrate was present. Water Environ. Res., 81, 2293 (2009).

Variables affecting melanoidins removal from molasses wastewater by coagulation/flocculation

Coagulation/flocculation process was applied in the polishing treatment of molasses wastewater on a bench-scale. Important operating variables, including coagulant type and dosage, solution pH, rapid mixing conditions as well as the type and dosage of polyeletrolytes were investigated based on the maximum removal efficiencies of chemical oxygen demand (COD) and color, residual turbidity and settling characteristics of flocs. HPSEC was utilized to evaluate the removal of molecular weight fractions of melanoidins-dominated organic compounds. Experimental results indicate that ferric chloride was the most effective among the conventional coagulants, achieving 89% COD and 98% color eliminations; while aluminum sulfate was the least effective, giving COD and color reductions of 66% and 86%, respectively. In addition to metal cations, counter-ions exert significant influence on the coagulation performance since Cl--based metal salts attained better removal efficiency than SO42--based ones at the optimal coagulant dosages. Coagulation of molasses effluent is a highly pH-dependent process, with better removal efficiency achieved at lower pH levels. Rapid mixing intensity, rather than rapid mixing time, has relatively strong influence on the settling characteristics of flocs formed. Lowering mixing intensity resulted in increasing settling rate but the accumulation of floating flocs. When used as coagulant aids, synthetic polyelectrolytes showed little effects on the improvement in organic removal. On the other hand, cationic polyacrylamide was observed to substantially enhance the settleability of flocs as compared to anionic polyacrylamide. The effects of rapid mixing conditions and polymer flocculants on the coagulation performance were discussed. (C) 2009 Elsevier B.V. All rights reserved.

In situ nutrient removal from aquaculture wastewater by aquatic vegetable Ipomoea aquatica on floating beds

Nutrient-rich effluents caused rising concern due to eutrophication of aquatic environment by utilization of a large amount of formula feed. Nutrient removal and water quality were investigated by planting aquatic vegetable on artificial beds in 36-m(2) concrete fishponds. After treatment of 120 days, 30.6% of total nitrogen (TN) and 18.2% of total phosphorus (TP) were removed from the total input nutrients by 6-m(2) aquatic vegetable Ipomoea aquatica. The concentrations of TN, TP, chemical oxygen demand (COD) and chlorophyll a in planted ponds were significantly lower than those in non-planted ponds (P<0.05). Transparency of water in planted ponds was much higher than that of control ponds. No significant differences in the concentration of total ammonia nitrogen (TAN), nitrate nitrogen (NO3-N) and nitrite nitrogen (NO2--N) were found between planted and non-planted ponds. These results suggested that planting aquatic vegetable with one-sixth covered area of the fishponds could efficiently remove nutrient and improve water quality.

Effects of thiamine on treatment performance of textile wastewater

Textile wastewater is commonly treated with activated sludge process technology. However, its treatment performance has not been demonstrated to be very effective. In this study, the effects of micronutrient thiamine on removal efficiencies of dissolved organic carbon (DOC) and chemical oxygen demand (COD) of textile wastewater in a batch test, together with its effect on the oxygen uptake rate (OUR) of activated sludge, were evaluated. Significant improvements were observed in the removal rates of DOC, COD and OUR with 121%, 156% and 121% of those of the control, respectively, when 0.5-2.0 mg/L thiamine was added to the wastewater treatment system. Thiamine could be probably used to improve the treatment performance of textile wastewater.

Bacterial diversity in activated sludge from a consecutively aerated submerged membrane bioreactor treating domestic wastewater

The bacterial diversity of activated sludge from submerged membrane bioreactor (SMBR) was investigated. A 16S rDNA clone library was generated, and 150 clones were screened using restriction fragment length polymorphism (RFLP). Of the screened clones, almost full-length 16S rDNA sequences of 64 clones were sequenced. Phylogenetic tree was constructed with a database containing clone sequences from this study and bacterial rDNA sequences from NCB1 for identification purposes. The 90.6% of the clones were affiliated with the two phyla Bacteroidetes (50%) and Proteobacteria (40%), and beta-, -gamma-, and delta-Proteobacteria accounted for 7.8%, 28.1%, and 4.7%, respectively. Minor portions were affiliated with the Actinobacteria and Firmicutes (both 3.1%). Only 6 out of 64 16S rDNA sequences exhibited similarities of more than 97% to classified bacterial species, which indicated that a substantial fraction of the clone sequences were derived from unknown taxa. Rarefaction analysis of operational taxonomic units (orrUs) clusters demonstrated that 150 clones screened were still insufficient to describe the whole bacterial diversity. Measurement of water quality parameter demonstrated that performance of the SMBR maintained high level, and the SMBR system remained stable during this study.

Effects of micronutrients on biological treatment efficiency of textile wastewater

Micronutrients play a very important role in biological processes for wastewater treatment. Many industrial wastewaters lack in nutrients (macronutrients and micronutrients) required for microbial growth, and this is one of the main problems at many activated sludge plants treating industrial wastewater. The microbial community structure is one of the important factors controlling the pollutant-degrading capacity of biological wastewater treatment system. In this study, the concentrations of micronutrients of the textile wastewater discharged from a textile plant were determined, and the effects of micronutrients on treatment efficiency and microorganism community structure of the biological treatment system were studied. The results showed that the optimal concentrations of magnesium, molybdenum, zinc, thiamine and niacin in the textile wastewater were 5.0, 2.0, 1.0, 1.0 and 1.0mg/L, respectively. The COD removal rates when magnesium, molybdenum, zinc, thiamine and niacin were added individually to the wastewater in their optimal concentrations were 1.8, 1.4, 1.3, 1.6 and 2.2 times of that of the control, respectively. The improving effects of combinations of zinc and thiamine, zinc and niacin, thiamine and niacin were better than single micronutrient. The diversity of quinones (DQ) changed significantly after the micronutrient was added into the wastewater treatment system. This indicated that there was probably a feasibility of optimizing the biological treatment performances and microorganism community structure of textile wastewater treatment system through micronutrient supplement.

Micronutrient niacin addition to enhance biological treatment of textile wastewater

Micronutrients play an important role in biological processes for wastewater treatment. Many industrial wastewaters lack in nutrients required for microbial growth, and this is one of the problems at many activated sludge plants treating them. In this study, the effects of the micronutrient niacin on the COD removal rates of textile wastewater, together with the effect of Mixed Liquor Suspended Solids (MLSS) on niacin, were studied. Certain improvement effects were found on the removal rates of COD, when 0.5 similar to 2.0 mg/L niacin was added to the textile wastewater. The optimal concentration of niacin was 1.0 mg/L, which was continuously added during textile wastewater treatment, and removal rates were 1.31 times compared to those of the control system. The concentration of MLSS was probably one of the factors influencing treatment efficiency, and the biological performance of treatment system could be optimized through micronutrient niacin supplements.

Roles of substrate microorganisms and urease activities in wastewater purification in a constructed wetland system

A vertical/reverse-vertical flow constructed wetland system was set up in Wuhan, China, to study its treatment efficiency of polluted lake water. The numbers of substrate microorganisms and urease activities in the substrate of the constructed wetland were determined by plate counts and colorimetric analysis, respectively. The removal efficiencies of biochemical oxygen demands (BOD5). chemical oxygen demands (COD), total phosphorus (TP), total Kjeldahl nitrogen (TKN), and total suspended solids (TSS) were measured by EPA approved methodology. The results showed there were significant positive correlations (P < 0.05) between numbers of microorganism in the substrate and removal rates of TKN and CODCr. Meanwhile, there was significant positive correlation (P < 0.05) between urease activities and removal efficiencies of TKN and negative correlation between urease activities and removal efficiencies of BOD5. Substrate microorganisms and urease activities played key factors during purification processes and they could be utilized as indicator of wastewater treatment performances in the constructed wetland system. (C) 2004 Elsevier B.V. All rights reserved.

The role of plants in channel-dyke and field irrigation systems for domestic wastewater treatment in an integrated eco-engineering system

Eight kinds of plants were tested in channel-dyke and field irrigation systems. The removal rates of TP, phosphate, TN, ammonia, CODcr and BOD, in the channel-dyke system with napiergrass (Pennisetum purpurem Schumach, x Pennisetum alopecuroides (L.) Spreng American) were 83.2, 82.3, 76.3, 96.2, 73.5 and 85.8%, respectively. The field irrigation systems with rice I-yuanyou No.1(88-132) (Oryza sativa L.) and rice II- suakoko8 (Oryza glaberrima) had high efficiency for N removal; the removal rate were 84.7 and 84.3%, respectively. The mass balance data revealed that napiergrass, rice I and II were the most important nutrient sinks, assimilating more than 50% of TP and TN. Plant uptake of N and P as percentage of total removal from wastewater correlated with biomass yield of and planting mode. (C) 2000 Elsevier Science B.V. All rights reserved.

Activated carbons chemically modified by concentrated H2SO4 for the adsorption of the pollutants from wastewater and the dibenzothiophene from fuel oils

The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150-270 degreesC. The modified AC was characterized by N-2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 degreesC greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m(2)/g to 745 m(2)/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon-oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 degreesC. The mesoporous properties of the AC modified by concentrated H2SO4 were further tested by the adsorption of methylene blue and dibenzothiophene. The AC modified by concentrated H2SO4 at 250 degreesC has much higher adsorption capacities for large molecules (e.g., methylene blue and dibenzothiophene) than the unmodified AC but less adsorption capacities for small molecules (e.g., iodine). The adsorption results from aqueous solutions have been interpreted using Freundlich adsorption models.