Innovative combined technique for high concentration of azo dye AR18 wastewater treatment using modified SBR and enhanced Fenton process as post treatment

The purpose of this research was to evaluate the performance of combined biological/advanced oxidation process (AOP) system for treatment of wastewater containing high concentration (500 mg/L) of azo dye Acid Red 18 (AR18). Two alternating anaerobic–aerobic sequencing batch reactors (SBR1 and SBR2 without and with external feeding at the beginning of aeration cycle, respectively) were operated. The effluent of the SBRs was then post treated through enhanced Fenton process (using zero-valent iron combined with ultrasonic irradiation). More than 90% and 97% of COD was removed in the combined SBR/AOP system without external carbon source (CTS1) and with external feeding (CTS2), respectively. The analysis of dye and its metabolites using UV–vis and HPLC analysis also proved that 99% of the original dye was decolorized and more than 89% of its metabolites were degraded through CST2 which is significantly higher than the reported values in the literature. Besides, more than 87% of phosphorus removal efficiency was obtained in CST2 compared to only 54.5% removal efficiency in CST1. Regarding the findings of this study, the proposed combined treatment system (CTS2) can be suggested as an effective technique for treatment of high azo dye AR18 concentration wastewater.     

MSBR法处理焦化废水

焦化废水成分复杂,是一种较难处理的工业废水.试验采用MSBR法对其进行处理,考察了5组水力停留时问(66h,39h,28 h,20 h,17 h)下不同反应阶段(厌氧池、缺氧池、好氧池、SBR出水)对水样的处理效果.结果显示,HRT总为66h条件下.CODCr去除率为82%,效果相对最好,并且每组HRT下焦化废水中的CODCr均是在 MSBR系统前置的厌/缺氧池(A2)已得到大幅度去除.但硝化作用受到抑制,NH3-N的去除效果并不明显.     

Evaluation of membrane bioreactor for hypersaline oily wastewater treatment

Produced water is a significant waste stream generated in association with oil and gas production. It contains high concentrations of hydrocarbon constituents and different salts. In this study, a membrane sequencing batch reactor (MSBR) was used to treat synthetic and real produced water. The MSBR was evaluated in terms of biodegradation of hydrocarbons in the synthetic produced water with various organic loading rates (OLR) (0.281, 0.563, 1.124, 2.248, and 3.372 kg COD/(m³ day)), cycle time (12, 24, and 48 h), and membrane performance. The effects of salt concentrations at different total dissolved solids (TDS) (35,000, 50,000, 100,000, 150,000, 200,000, and 250,000 mg/L) on biological treatment of the pollutants in the synthetic and real wastewater were studied. At an OLR of 1.124 kg COD/(m³ day), an HRT of 48 h and TDS of 35,000 mg/L, removal efficiencies of 97.5%, 97.2%, and 98.9% of COD, total organic carbon (TOC), and oil and grease (O&G), respectively were achieved. For the real produced water, removal rates of 86.2%, 90.8%, and 90% were obtained for the same conditions. However, with increasing salt content, the COD-removal efficiencies of the synthetic and real produced water were reduced to 90.4% and 17.7%, respectively at the highest TDS.     

Investigation of affecting parameters on treating high-strength compost leachate in a hybrid EGSB and fixed-bed reactor followed by electrocoagulation–flotation process

In this research, treatability of high-load compost leachate in a hybrid expanded granular sludge bed (EGSB) and fixed-bed (FB) bioreactor followed by electrocoagulation–flotation (ECF) system was examined. The operational factors in EGSB–FB were influent chemical oxygen demand (COD), hydraulic retention time (HRT) and COD/nitrogen ratio (COD/N). And, their interactive effects on the efficiency of COD removal and biogas production rate (BPR) as responses were analyzed and correlated by response surface methodology (RSM). The optimum conditions of the hybrid EGSB–FB reactor were acquired at COD = 7800 mg/L, HRT = 35 h, COD/N = 70, in which COD removal efficiency was 83% and BPR 94 mL/h. The amount of confidence interval was 95%. COD (relevant coefficient = 9.8) and HRT (relevant coefficient = −24) were resulted respectively as the most effective parameters on COD removal and BPR. Yet, COD/N parameter imposed negative effect on COD removal and BPR in values less than about 100. The outcomes indicated that operated ECF as post-treatment in constant conditions (electrolysis time = 75 min, electrodes distance = 3 cm, voltage = 20 V) successfully satisfied discharge criteria in the most part of experimental domains.     

太湖草型区与藻型区沉积物中聚磷菌富集试验研究

采用序批式反应器(SBR)小型反应装置,以葡萄糖和丙酸为碳源,在厌氧/好氧条件下,对太湖草型区和藻型区的沉积物进行聚磷菌富集培养。探讨了太湖草型区和藻型区沉积物中聚磷菌的存在性和差异性。试验结果表明,通过实验室模拟条件培养,发现太湖沉积物存在聚磷细菌。两种碳源培养的草型区沉积物厌氧释磷量高于藻型区。以葡萄糖为碳源培养的草型区和藻型区沉积物厌氧释磷现象微弱,好氧磷的超量吸收现象比活性污泥弱,对PO34--P的平均去除率分别为34.95%、38.17%。而在以丙酸为碳源的系统中,有着明显的厌氧释磷和好氧摄磷现象,对PO34--P的平均去除率分别为41.27%、51.35%。     

Two-stage biodegradation coupled with ultrafiltration for treatment of municipal landfill leachate

The municipal landfill leachate was treated in a hydrolysis–acidification reactor (HAR)/aerobic bio-contact oxidation reactor (ABOR) following a pretreatment with ultrafiltration (UF) membrane. Experiments were conducted continuously for 44 days at a constant flow rate of 20 l d⁻¹ and organic loading rates (OLRs) from 0.75 to 1.5 kgCOD m⁻³ per day. The results showed that COD of the leachate steadily decreased from 20,015 mg l⁻¹ to less than 3000 mg l⁻¹, and NH₄-N decreased from 368.6 mg l⁻¹ to 259.3 mg l⁻¹ in the UF process. The COD and NH₄-N removal efficiency of HAR was 56.7% and 27.7%, and that of ABOR was 94.6% and 86.7%, respectively. The total COD and NH₄-N removal efficiency reached 99.6% and 93.2%, respectively. UF and HAR played a critical role in raising the biodegradability of the landfill leachate, while ABOR had an important function on removing the dissolved NH₄-N in leachate.     

高浓度有机牧场养牛废水处理工程的设计与运行

针对南昌某有机牧场的养牛废水悬浮物、有机物、氨氮浓度高等特点,采用厌氧消化-UASB-SBR组合处理工艺,进水COD为18～20 g/L、NH3-N为410～510 mg/L、SS为4～6 g/L,通过工程调试和运行后,出水COD、NH3-N和SS去除率分别为98.1%、76.1%、97.5%,各指标均达到了《畜禽养殖业污染物排放标准》(GB 18596—2001)的要求。对南方地区的养殖场废水处理工程具有一定的参考价值。     

Performance of a pilot scale up-flow septic tank for on-site decentralized treatment of residential wastewater

The aim of this research was to study the on-site anaerobic treatment of a medium-strength residential wastewater in a pilot-scale up-flow septic tank (UST). The effects of three different hydraulic retention times (HRTs) of 24, 12 and 6 h on the UST performance were investigated. The UST removed 85, 77, and 86% of biochemical oxygen demand (BOD₅), chemical oxygen demand (COD) and total suspended solids (TSS), respectively, at steady state operation and with a 24 h HRT. Decreasing the HRT to 12 and then 6 h resulted in deteriorated effluent quality and significantly reduced reactor performance. The sludge showed a high specific methanogenic activity (SMA) of 15.2 mL CH₄ g^?1 VSS d^?1 with raw wastewater substrate. The solids accumulated in the tank by the end of the experiment had a VSS/TSS of 0.57, demonstrating significant stabilization. Overall, the UST is concluded to be a technically and economically promising alternative to conventional septic tanks for the on-site decentralized treatment of residential wastewater, particularly in the rural communities of developing countries.     

以硝酸盐为主要氮源的反硝化除磷细菌驯化

以活性污泥为种泥,通过序批式反应器(Sequencing Batch Reactor,SBR),在厌氧-缺氧-好氧交替的条件下驯化培养以硝酸盐为主要氮源的反硝化除磷细菌(Denitrifying Phosphorus-Accumulating Organisms,DPAO)。在330 d的培养时间内监测磷酸盐、硝酸盐和亚硝酸盐等常规指标,并研究驯化不同阶段的一个周期内各指标的变化及进行相应的动力学分析。结果表明,随着驯化的进行,厌氧阶段释磷速率逐渐增加,释磷量也相应增大,出水磷质量浓度最终维持在0.8mg/L,去除率达到91.8%,硝氮全部去除。通过对16S r RNA测序结果的比对,得到聚磷菌占总菌的76.93%,反硝化除磷菌占聚磷菌的一半以上。而聚糖菌仅占5.13%,聚磷菌成为优势菌种。此外,在整个驯化过程中,水质和环境条件的变化使出水中磷质量浓度出现波动,而出水硝氮的变化不大。研究表明,以硝酸盐作为主要氮源培养反硝化除磷细菌的方式是可行的,并有利于聚磷菌对聚糖菌的竞争,使聚磷菌成为优势菌种。     

A cost effective method for decentralized sewage treatment

The aim of this research was to upgrade the performance of a conventional septic tank (CST) for on-site treatment of sewage with negligible costs. Although CST is known as an inexpensive pre-treatment system, a complementary treatment is required to reuse its output effluent. In this work, the quality of treated wastewater reached to the standard level for irrigation by the innovational changes made in the structure of CST for converting it into an advanced septic reactor (ASR). The modification consists adding some pipe and trays without using any mechanical or electrical equipment.ASR was operated at ambient temperatures in laboratory and pilot-scale. The effects of up-flow velocities (V_up) of 0.4, 0.5, 0.7, 1 and 1.5 m/h and hydraulic retention times (HRT) of 36, 24 and 12 h on the ASR treatment performance were studied.For optimum V_up of 1 m/h and HRT of 24 h and biomass specific methanogenic activity (SMA) of 0.31 mg COD/g VSS d the maximum removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD5) and total suspended solids (TSS) were 86.2%, 79.4% and 95%, respectively.The results showed that ASR is an appropriate alternative for CST for sewage on-site treatment by a low cost modification.     

UASB+SBR工艺处理皂素生产废水的快速启动研究

皂素生产废水为难处理高浓度酸性含硫有机废水.其中高含量的硫酸盐在厌氧条件下产生大量的H2S,造成了对厌氧微生物的抑制作用,严重影响厌氧生物处理的效果,甚至使厌氧消化完全失败,使该类废水的处理较为困难.为了有效解除硫酸盐对生物处理设施中微生物的抑制,找出皂素生产废水的快速启动运行的方法,本文选用了UASB SBR组合工艺进行了2个月左右的动态连续流实验,对硫酸盐抑制的解除方法进行了研究,提出了相应的解除硫酸抑制厌氧消化的方法,找到了UASB快速启动的有效方法.小试连续运行实验结果表明,在UASB中加入适量铁屑和活性炭颗粒,以生活污水处理厂剩余污泥为种泥可以成功实现UASB SBR处理系统的快速启动,消除DO2-4对生物处理系统的影响,并在较短的时间内(21 d左右)培养出了厌氧颗粒污泥.UASB启动后,在进水COD质量浓度34 000mg/L左右时,COD的去除率一直保持在95%以上,出水COD质量浓度维持在1 300 mg/L左右.厌氧出水经过SBR处理后,出水水质达到了<综合污水排放标准>中的二级排放标准要求.该快速启动方法可供类似酸性高浓度有机废水处理和调试参考.     

Modeling of a sequencing batch reactor treating municipal wastewater using multi-layer perceptron and radial basis function artificial neural networks

A sequencing batch reactor was modeled using multi-layer perceptron and radial basis function artificial neural networks (MLPANN and RBFANN). Then, the effects of influent concentration (IC), filling time (FT), reaction time (RT), aeration intensity (AI), SRT and MLVSS concentration were examined on the effluent concentrations of TSS, TP, COD and NH₄⁺-N. The results showed that the optimal removal efficiencies would be obtained at FT of 1 h, RT of 6 h, aeration intensity of 0.88 m³/min and SRT of 30 days. In addition, COD and TSS removal efficiencies decreased and TP and NH₄⁺-N removal efficiencies did not change significantly with increases of influent concentration. The TSS, TP, COD and NH₄⁺-N removal efficiencies were 86%, 79%, 94% and 93%, respectively. The training procedures of all contaminants were highly collaborated for both RBFANN and MLPANN models. The results of training and testing data sets showed an almost perfect match between the experimental and the simulated effluent of TSS, TP, COD and NH₄⁺-N. The results indicated that with low experimental values of input data to train ANNs the MLPANN models compared to RBFANN models are more precise due to their higher coefficient of determination (R²) and lower root mean squared errors (RMSE) values.     

Electro-Fenton degradation of cationic red X-GRL using an activated carbon fiber cathode

We reported the study of the degradation of the azo dye cationic red X-GRL by the electro-Fenton process using an activated carbon fiber cathode. The electrogeneration of hydrogen peroxide in solution using different material cathodes fed with air was investigated, and the results revealed that the activated carbon fiber cathode was more effective compared to the graphite cathode. The decolorization and mineralization of cationic red X-GRL were also determined. The effect of the operating parameters, such as the initial Fe²⁺ concentration, temperature and initial dye concentration, was investigated. The optimum Fe²⁺ catalyst concentration values for the degradation of cationic red X-GRL was found to be 5 mM. The rate of decolorization and mineralization of dye could be accelerated by increasing the temperature. In addition, the decolorization and total organic carbon (TOC) removal efficiency decreased with the increasing initial dye concentration, while the TOC removal increased. Two different transition metal ions (Cu²⁺ and Mn²⁺) were applied as substitutes for ferrous sulfate for evaluating catalytic effect. The results indicated that Cu²⁺ and Mn²⁺ were more effective than Fe²⁺ in catalyzing the degradation of the dye.     

去除制革废水氨氮的工程实例

成都某制革厂设计水量1 600 m3/d,采用"物化处理 生化处理"的工艺.ABR折板式厌氧池使废水中大量有机氮分解为氨氮,厌氧出水氨氮高达100 mg/L左右.针对这种情况,把SBR曝气池活性污泥的培养分为2个阶段,第1阶段使污泥适应此制革废水,并使其对COD有较高的去除率;第2阶段为培养硝化菌阶段,使自养型的硝化菌逐渐增多,活性加强.在第2阶段注意控制碱度和溶解氧,最终使曝气池中硝化菌在无外加碱度的条件下对氨氮有高的去除率.     

Removal of humic substances from landfill leachate by Fenton oxidation and coagulation

In this study, chemical oxygen demand (COD) was characterized as total organic constituents and the isolated humic substances (HS) were characterized as an individual organic contaminant in landfill leachate. It was found that the HS content of landfill leachate was 83.3%. The results of laboratory tests to determine the roles of HS in reducing the organic content of landfill leachate during Fenton process are presented. Furthermore, the performances of oxidation and coagulation of Fenton reaction on the removal of HS and COD from leachate were investigated. The change curves of HS removal were similar to those of COD. The HS removal was 30% higher than COD removal, which indicated that HS were mostly degraded into various intermediate organic compounds but not mineralized by Fenton reagent. The oxidation removal was greatly influenced by initial pH relative to the coagulation removal. The oxidation and coagulation removals were linear dependent with hydrogen peroxide and ferrous dosages, respectively. Ferrous dosage greatly influenced the coagulation removal of COD at low ratio ([H₂O₂]/[Fe²⁺] < 3.0), but not at extremely high ratio ([H₂O₂]/[Fe²⁺] > 6.0). The coagulation removal of HS was not affected obviously by oxidation due to both Fenton oxidation and coagulation remove high molecular weight organics preferentially. Higher temperature gave a positive effect on oxidation removal at low Fe²⁺ dosage, but this effect was not obvious at high Fe²⁺ dosage.     

碳源和硝酸盐对SBBR反硝化除磷影响的试验研究

研究碳源和硝酸盐对填加聚氨酯载体的SBBR反硝化除磷的影响。在SBR中填加聚氨酯载体,将生物膜法和活性污泥法相结合,形成序批式生物膜反应器(SBBR),在厌氧/缺氧交替运行条件下利用NO3-作为电子受体,研究NaAc浓度、NaAc与丙酸钠的比例、NO3-浓度及NO3-投加方式等因素对除磷效果的影响。PO43-质量浓度在9~11 mg/L之间,COD质量浓度为200 mg/L时,SBBR有较佳的除磷效果;当进水NaAc与丙酸钠配比为2时,进水COD自身降解速率较慢,且不影响除磷效果;分批次(这里分2次)投加硝酸盐有利于硝酸盐向亚硝酸盐的转化;NO3-质量浓度为65 mg/L左右时,能获得较好的除磷、除氮效果。填加聚氨酯载体的SBR装置除磷效果较理想;碳源和硝酸盐对SBBR反硝化除磷影响显著。     

Pretreatment of municipal landfill leachate by a combined process

Biodegradability enhancement of landfill leachate using air stripping followed by coagulation/ultrafiltration (UF) processes was introduced. The air stripping process obtained a removal efficiency of 88.6% for ammonia nitrogen (NH₄–N) at air-to-liquid ratio of 3500 (pH 11) for stripping 18 h. The single coagulation process increased BOD/COD ratio by 0.089 with the FeCl₃ dosage of 570 mg l^?1 at pH 7.0, and the single UF process increased the BOD/COD ratio to 0.311 from 0.049. However, the combined process of coagulation/UF increased the BOD/COD ratio from 0.049 to 0.43, and the final biological oxygen demand (BOD), chemical oxygen demand (COD), NH₄–N and colour of leachate were 1223.6 mg l^?1, 2845.5 mg l^?1, 145.1 mg l^?1 and 2056.8, respectively, when 3 kDa molecular weight cut-off (MWCO) membrane was used at the operating pressure 0.7 MPa. In ultrafiltration process, the average solution flux (J_V), concentration multiple (M_C) and retention rate (R) for COD was 107.3 l m^?2 h^?1, 6.3% and 84.2%, respectively.     

序批式厌氧反应器厌氧氨氧化渗滤液脱氮试验研究

通过接种具有厌氧氨氧化性能的污泥,采用序批式厌氧反应器(ASBR)处理垃圾渗滤液,研究水力停留时间(HRT)、pH、温度等对厌氧氨氧化反应过程的影响并确定各因素的最佳控制范围。结果表明,在本试验条件下,HRT、pH和温度的适宜范围分别为24 h、7.5~8.5和35℃。在此条件下,进水NH~+_4-N浓度为150 mg/L,NO~-_2-N浓度为160 mg/L,COD浓度为300 mg/L时,出水NH~+_4-N、NO~-_2-N、TN、COD平均浓度分别为15.5 mg/L、0.01mg/L、43.2 mg/L和152.1 mg/L,相对应的平均去除率分别为89.7%、99.9%、86.1%和47.6%。     

餐厨垃圾厌氧干发酵处理产甲烷潜力及动力学研究

研究采用中温厌氧干发酵反应器,针对餐厨垃圾厌氧干发酵过程中p H,VFA,COD和产气量的变化,结合修正Gompertz方程分析厌氧干发酵产甲烷的动力学过程。在中温厌氧干发酵系统负荷和初始条件下,分析厌氧干发酵产甲烷过程变化,建立厌氧干发酵产甲烷模型,对其预测和试验验证及误差进行分析。结果表明,在中温厌氧干发酵过程中p H先下降后上升,VFA浓度先增加后减少,COD去除率保持在76.02%~90.28%之间;修正Gompertz动力学模型,可以较好地分析餐厨垃圾厌氧干发酵产甲烷过程(决定系数R~20.99),经拟合,具有较高的产甲烷能力,且与试验结果显著相关;在检验水平a=0.05条件下,其方差分析的P值为0.938,大于0.05的显著性,表明模型能较好地预测厌氧干发酵累积产甲烷量。     

Modeling and optimization of a sono-assisted photocatalytic water treatment process via central composite design methodology

This work focuses on modeling and optimization of a sono-assisted photocatalytic decolorization process of a model pollutant, azo dye C.I. direct red 16 (DR16). In the process, a high temperature thermal decomposition nano synthesized titanium dioxide (TD-TiO₂) was applied as photocatalyst. Central composite design (CCD) methodology was used for designing the experiments, modeling and optimization of the process. A quadratic model was established to describe dependency of the decolorization efficiency (DE), as the model response, to some effective operational parameters, i.e. the catalyst dosage, pH and the dye initial concentration. The ANOVA analysis confirmed that all of the variables have significant influence on the model response. Under the established optimum conditions, 92.4% DE was achieved after 45 min; however, to access desirable mineralization efficiency, the process should be continued up to 120 min. All withdrawn samples from the reaction media during the process showed no antibacterial activity, which indicates safety of the treated effluent for disposal into the environment. Also studies showed that the process proceeds via two parallel branches of photolysis and photocatalysis, where propagation of the ultrasonic waves into the reaction media plays a vital promoting role on the latter branch.