Investigating the quantitative and qualitative status of effluent in the wastewater treatment plant in Iran Central Iron Ore

The aim of present study was to investigate the quality of the produced effluent from different units of the Iran Central Iron Ore in Bafq city and comparison of effluent with the standards. This study presents the physicochemical and biological parameters data of effluent of three Sequencing batch reactors (SBR) with a capacity of 160 m³?d^?1. Most common parameters include pH, total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), heavy metals, and total coliforms and fecal coliforms as biological indicators. Then, for each SBR system, the average of each parameter was determined, and results were compared with the standard recommended by the Iranian Environmental Protection Agency. Based on the results, some of the parameters, including BOD₅, COD, and TSS in the wastewater treatment plant (WWTP) effluent, are higher than the permitted amount for discharge to the surface water. Considering the BOD₅, COD, and TSS concentration in WWTPs, the treated wastewater is only suitable for agricultural and irrigation use. Therefore, wastewater produced by Iran Central Iron Ore Co. will need additional treatment to achieve standard quality of water before discharge in surface water and adsorbent well.     

Anaerobic-aerobic treatment of purified terephthalic acid (PTA) effluent; a techno-economic alternative to two-stage aerobic process

This paper addresses the treatment of purified terephthalic acid (PTA) effluent using anaerobic and aerobic processes. Laboratory studies were carried out on flow proportionate composite wastewater generated from the manufacturing of PTA. An activated sludge process (ASP-two stage and single stage) and an upflow anaerobic fixed film fixed bed reactor (AFFFBR) were used, individually and in combination. The performance of a full-scale ETP under existing operating conditions was also studied. Full scale ETP studies revealed that the treatment of PTA effluent using a two-stage ASP alone does not meet treated effluent quality within the prescribed Indian Standards. The biomass produced in the two stage ASP was very viscous and fluffy and the sludge volume index (SVI) was very high (200-450 ml/g). However, pretreatment of PTA effluent using an upflow AFFFBR ensured substantial reduction in BOD (63%) and COD (62%) with recovery of biogas at 1.8-1.96 l/l effluent treated at a volumetric loading rate (VLR) 4-5 kg COD/m(3) d. The methane content in the biogas varied between 55% and 60%. The pretreated effluent from the upflow AFFFBR was then treated through a single stage ASP. The biomass produced in the ASP after anaerobic treatment had very good settlability (SVI: 75-90 ml/g) as compared to the two stage ASP and the treated effluent quality with respect to BOD, COD and SS was within the prescribed Indian Standards. The alternative treatment process comprising an upflow AFFFBR and a single stage ASP ensured net power saving of 257 kW and in addition generated 442 kW of power through the AFFFBR.     

Aerobic treatment of palm oil mill effluent

In this study treatment of palm oil mill effluent (POME) was investigated using aerobic oxidation based on an activated sludge process. The effects of sludge volume index, scum index and mixed liquor suspended solids during the acclimatizing phase and biomass build-up phase were investigated in order to ascertain the reactor stability. The efficiency of the activated sludge process was evaluated by treating anaerobically digested and diluted raw POME obtained from Golden Hope Plantations, Malaysia. The treatment of POME was carried out at a fixed biomass concentration of 3900+/-200mg/L, whereas the corresponding sludge volume index was found to be around 105+/-5mL/g. The initial studies on the efficiency of the activated sludge reactor were carried out using diluted raw POME for varying the hydraulic retention time, viz: 18, 24, 30 and 36h and influent COD concentration, viz: 1000, 2000, 3000, 4000 and 5000mg/L, respectively. The results showed that at the end of 36h of hydraulic retention time for the above said influent COD, the COD removal efficiencies were found to be 83%, 72%, 64%, 54% and 42% whereas at 24h hydraulic retention time they were 57%, 45%, 38%, 30% and 27%, respectively. The effectiveness of aerobic oxidation was also compared between anaerobically digested and diluted raw POME having corresponding CODs of 3908 and 3925mg/L, for varying hydraulic retention time, viz: 18, 24, 30, 36, 42, 48, 54 and 60h. The dissolved oxygen concentration and pH in the activated sludge reactor were found to be 1.8-2.2mg/L and 7-8.5, respectively. The scum index was found to rise from 0.5% to 1.9% during the acclimatizing phase and biomass build-up phase.     

Sustainability of wastewater treatment technologies

A set of indicators that incorporate environmental, societal, and economic sustainability were developed and used to investigate the sustainability of different wastewater treatment technologies, for plant capacities of <5 million gallons per day (MGD) or 18.9 x 10(3) cubic meters (m(3)/day). The technologies evaluated were mechanical (i.e., activated sludge with secondary treatment), lagoon (facultative, anaerobic, and aerobic), and land treatment systems (e.g., slow rate irrigation, rapid infiltration, and overland flow). The economic indicators selected were capital, operation and management, and user costs because they determine the economic affordability of a particular technology to a community. Environmental indicators include energy use, because it indirectly measures resource utilization, and performance of the technology in removing conventional wastewater constituents such as biochemical oxygen demand, ammonia nitrogen, phosphorus, and pathogens. These indicators also determine the reuse potential of the treated wastewater. Societal indicators capture cultural acceptance of the technology through public participation and also measure whether there is improvement in the community from the specific technology through increased job opportunities, better education, or an improved local environment. While selection of a set of indicators is dependent on the geographic and demographic context of a particular community, the overall results of this study show that there are varying degrees of sustainability with each treatment technology.     

Performance assessment of a wastewater treatment plant producing effluent for irrigation in Egypt

A conventional activated sludge treatment facility was the subject of this study. The assessment was directed at determining the characteristics of the raw wastewater, the quality of the treated effluent and the efficiency of the various treatment units. Furthermore, the water quality along the effluent irrigation canal was monitored. The assessment of the quality of the treated effluent for irrigation is based on the guidelines established by the World Health Organization and the Egyptian decree 9/89 for the use of wastewater in agriculture. The results of the study indicated that the concentration of the raw wastewater was considered moderate. The mean values of the COD (Chemical Oxygen Demand), BOD (Biological Oxygen Demand) and total suspended solids (TSS) were around 250, 102 and 142 mg l–1, respectively. This was attributed to the high quantities of wastewater from industrial sources. The overall efficiency of the treatment facility was good. The mean residual COD, BOD and TSS were 25, 8 and 21 mg l–1 and the corresponding percentage removal values were 90, 92 and 85%, respectively. The maximum percentage removal of oil and grease was 84% with a mean residual concentration of 24 mg l–1. The total viable count (22°C and 37°C), faecal coliform and aecal streptococci were reduced by 99.9% compared to only 99.5% for Salmonella. Bacteriological examination of the dried sludge indicated a reduction of nine logs of faecal coliform and faecal streptococci, as compared to thickened sludge. Analysis of the Ni, Cu, Pb and Cr in the dried sludge indicated that their concentrations are within the permissible limits. Zinc exceeded the consent standards by 50%. The results of the analyses of samples collected at the beginning of the irrigation canal indicated insignificant changes from the characteristics of the final effluent. Samples collected at a distance of 2km along the irrigation canal showed mean reductions in the COD and BOD of 28.6 and 47%, respectively, which could be attributed to sedimentation and/or a self-purification effect. An increase in the total nitrogen, total phosphorus and total viable count was also recorded, which could be due to seepage from the agricultural land. From the data available it is evident that the treated wastewater could be used for restricted irrigation. The design and implementation of a monitoring programme is recommended.     

综合治理电镀废水,实现达标排放

我们对原来因废水超标排放而被关闭的电镀车间,提出了废水达标排放的优化设计改造方案,经过电解,物理法对原来的处理工艺进行综合改造以后,废水达标循环使用,实现了设计予定目标,恢复了生产,做到经济效益、环境效益共同提高,行进合理,有推广应用价值。     

高级催化氧化法处理高含盐废水研究

针对风城油田生产废水高盐、高温、高矿化度、可生化性差等水质特性,现场采用“混凝沉降+高级催化氧化”工艺,处理后出水达到《污水综合排放标准》GB8978中二级排放标准。混凝沉降阶段COD去除率为36~49%,挥发酚去除率为11~21%,石油类去除率为42~69%;催化氧化阶段COD去除率为20%~40%,挥发酚去除率为69%~73%,石油类去除率为16%~20%。     

Assessment of AWT systems in the metro Atlanta area

A study was conducted to evaluate the performance of six advanced wastewater treatment facilities using biological nutrient removal processes as the primary mechanism for removing carbon, nitrogen, and phosphorus from domestic wastewater. One year of operating data was obtained from monthly operating reports provided by the Georgia Environmental Protection Division (EPD) in Atlanta. Additional information about facility operations and the types of chemicals used was gathered through review of EPD files and interviews with plant personnel. Data evaluated were: influent and effluent five-day Biochemical Oxygen Demand (BOD(5)); influent and effluent total suspended solids (TSS); influent Total Kjeldahl Nitrogen and effluent Total Nitrogen; and influent and effluent Total Phosphorus (TP). Although varying from plant to plant, effluent requirements for BOD(5), TSS, ammonia, and TP were met. Chemicals utilized, design capacity, and monthly effluent concentrations are presented in this study.     

芦苇生态湿地系统处理造纸废水的探讨

根据造纸污水的特点,在科学详细地分析、评价、论证了现有造纸污水处理技术的基础上,从滨州市的实际情况出发,充分分析了应用湿地生态技术处理造纸污水的可行性,对造纸企业实现环保与经济双赢具有很好的指导作用.     

活性污泥法的发展及其工程选择

本文阐述了城市污水处理活性污泥法的发展沿革,着重介绍了近三十年出现的几个重要工艺的特点;文中还提出在建设中、小城市污水处理厂时对工艺行根据。建设在目前应更多关注SBR,UNITANK及OD工艺。     

O2-Fenton试剂处理对氨基苯磺酸废水的探讨

利用由O2和Fenton试剂组成的类Fenton系统处理对氨基苯磺酸废水,取得了很好的降解效果.当FeSO4(10g/L)投加量为1.2mL、H2O2(3%)投加量为3mL时,COD去除率可达到70%.     

ASM模型中四个基质组分测定研究

随着ASM系列数学模型的发展，废水特性的鉴定成为一个重要的研究课题。与传统的废水特性鉴定不同，按照ASM模型要求，传统的COD被划分为四个部分。在对广州市污水和污泥特性的研究中，针对这四个部分，结合物理方法和生物方法。采用了一种简单与便于实施的测定方法。     

Nitrogen recovery in an integrated system for wastewater treatment and tilapia production

An integrated system, consisting of Up-flow Anaerobic Sludge Blanket (UASB)-duckweed-tilapia ponds was used for recovery of sewage nutrients and water recycling. A UASB reactor with 40 liter working volume was used as pre-treatment unit followed by a series of three duckweed ponds for nitrogen recovery. The treated effluent and duckweed biomass was used to feed fishponds stocked with Nile tilapia (Oreochromis niloticus). The UASB reactor was fed with raw, domestic sewage at 6 h hydraulic retention time. The three duckweed ponds were stocked with Lemna gibba and fed with UASB effluent at 15 days hydraulic retention time. Nitrogen recovery from UASB effluent via duckweed biomass represented 81% of total nitrogen removal and 46.5% from the total nitrogen input to the system. In subsequent fishponds the nitrogen recovery from duckweed as fish feed was in the range of 13.4–20%. This nitrogen in fish biomass represented 10.6–11.5 g N from the total nitrogen in the raw sewage fed to the UASB reactor. The growth performance of tilapia (Oreochromis niloticus) showed specific growth rates (SGR) in the range of 0.53–0.97. The range of feed conversion ratio (FCR) and protein efficiency ratio (PER) were 1.2–2.2 and 2.1–2.28, respectively. The results of the experiments showed total fish yield and net fish yield in the range of 17–22.8 ton/ha/y and 11.8–15.7 ton/ha/y respectively. In conclusion UASB-duckweed-tilapia ponds provide marketable by-products in the form of duckweed and fish protein, which represent a cost recovery for sewage treatment.     

Para-chlorophenol containing synthetic wastewater treatment in an activated sludge unit: effects of hydraulic residence time

Due to the toxic nature of chlorophenol compounds present in some chemical industry effluents, biological treatment of such wastewaters is usually realized with low treatment efficiencies. Para-chlorophenol (4-chlorophenol, 4-CP) containing synthetic wastewater was treated in an activated sludge unit at different hydraulic residence times (HRT) varying between 5 and 30 h while the feed COD (2500 mg l(-1)), 4-CP (500 mg l(-1)) and sludge age (SRT, 10 days) were constant. Effects of HRT variations on COD, 4-CP, toxicity removals and on settling characteristics of the sludge were investigated. Percent COD removals increased and the effluent COD concentrations decreased when HRT increased from 5 to 15 h and remained almost constant for larger HRT levels. Nearly, 91% COD and 99% 4-CP removals were obtained at HRT levels above 15 h. Because of the highly concentrated microbial population at HRT levels of above 15 h, low effluent (reactor) 4-CP concentrations and almost complete toxicity removals were obtained. High biomass concentrations obtained at HRT levels above 15 h were due to low 4-CP contents in the aeration tank yielding negligible inhibition effects and low maintenance requirements. The sludge volume index (SVI) decreased with increasing HRT up to 15 h due to high biomass concentrations at high HRT levels resulting in well settling sludge with low SVI values. Hydraulic residence times above 15 h resulted in more than 90% COD and complete 4-CP and toxicity removals along with well settling sludge.     

Emergy evaluation of an integrated livestock wastewater treatment system

Wastewater treatment practices should pay more attention to their environmental performances due to their resources consumption and emissions’ impact. While reclaimed water reuse seems to have become a promising practice, is it always feasible in any condition? To address this issue, this study carried out an extended emergy evaluation of a holistic wastewater treatment system. On one hand, this method was extended to include the emissions’ impact. On the other hand, this study integrated a wastewater treatment plant, its excess sludge disposal system and treated water disposal system into an integrated wastewater treatment system (IWTS), so as to evaluate its performances more completely. And then several indicators, including cost per unit pollutant eliminated (CUPE), ratio of positive output (RPO), environmental load ratio (ELR), and sustainability index (SI), were proposed for evaluating the performances of an IWTS. Two scenarios (scenario A: wastewater treatment + sludge landfilling + treated water discharges; scenario B: wastewater treatment + sludge landfilling + reclaimed water reuse) for a livestock wastewater treatment plant in Sichuan Agricultural University located in Ya’an City in Southwest China, as cases, were researched. The results show that scenario B has lower positive output efficiency and greater environmental load than scenario A. Meanwhile, the reclaimed water reuse raises cost per unit pollutant eliminated compared with the treated water being discharged directly; emissions’ impact enhances the environmental load of the two scenarios to different degree; emissions’ impact has decisive effect on the sustainability of the two scenarios. These results mean that the reclaimed water reuse should not be advocated in this case. This study provides some policy implications: (1) wastewater treatment process should be comprehensively evaluated from its resources consumption and impact of emissions; (2) reclaimed water reuse should be carefully evaluated from its pros and cons simultaneously; (3) the local conditions should be considered when implementing reclaimed water reuse, such as local water body conditions, market demands, the related laws and regulations, corporations’ economic conditions, etc.     

Preliminary study of physico-chemical treatment options for hospital wastewater

Hospital effluents are loaded with pathogenic microorganisms, partially metabolized pharmaceutical substances, radioactive elements, and other toxic substances. Such effluents if not treated properly can damage the natural environment and create a biological imbalance. This paper points out the areas of concern for hospital wastewater disposal and reports the findings of a limited physico-chemical study of treatment options for hospital effluents conducted at Christian Medical College and Hospital, Vellore, Tamil Nadu. The effluent collected was checked for conventional parameters and subjected to coagulation experiments. The raw and settled effluents were coagulated with FeCl(3), filtered and disinfected. Physico-chemical treatment seems to be an attractive option for the cost-effective disposal of hospital effluents. The results of this study call for further detailed study in this area.     

超滤技术在废水处理中的应用

文章对超滤原理、超滤膜种类、国内外超滤技术发展现状等做了较详尽的阐述,同时着重介绍了超滤技术在油田含油废水、石化含油废水、金属加工用乳化废液、纤维加工油剂废水及羊毛精制废水中回收羊毛脂的应用实例。     

Biological treatment of 2,4,6-trichlorophenol (TCP) containing wastewater in a hybrid bioreactor system with effluent recycle

Due to the toxic effects of trichlorophenol (TCP) on microorganisms, biological treatment efficiencies of TCP containing wastewaters are usually low. Synthetic wastewater containing 2,4,6-TCP was biologically treated in a hybrid-loop bioreactor system consisting of a packed column biofilm and an aerated tank bioreactor with effluent recycle in order to improve COD and TCP removals. Effects of the feed TCP concentration on COD, TCP and toxicity removal performance of the system were investigated for the feed TCP between 50 and 450 mg L(-1) while the sludge age (solids retention time, SRT) and hydraulic residence time (HRT) were kept constant at 20 d and 25 h, respectively. Biomass concentrations in the packed column and in the aeration tank decreased with increasing feed TCP concentrations due to toxic effects of TCP on the organisms. Low biomass concentrations in the system at high feed TCP contents resulted in low COD, TCP and toxicity removals. Therefore, percent TCP, COD and toxicity removals decreased with increasing feed TCP concentrations especially above 400 mg L(-1). The effluent TCP concentrations were lower than 20 mg L(-1) for the feed TCP concentrations below 390 mg L(-1) resulting in TCP and COD removals above 90%. Specific rates of TCP and COD removals increased with the feed TCP due to low biomass concentrations at high TCP contents. The system should be operated at a feed TCP lower than 400 mg L(-1) in order to obtain more than 90% TCP, COD and toxicity removals under the specified experimental conditions.     

Performance of a combined anaerobic reactor for municipal wastewater treatment at ambient temperature

A bench-scale experimental study was carried out to investigate the overall performance of a combined anaerobic reactor for treating pre-settled municipal wastewater at ambient temperature (18–28°C) in terms of substrate removal efficiencies, biogas, methane production, volatile fatty acid (VFA) profiles and effluent suspended solids (SS) concentration, etc. The tested reactor was a modified anaerobic baffled reactor (ABR). The second and third compartments were partly packed with supporting media. The experimental results were similar to, or compared favourably with, other anaerobic reactor systems for municipal wastewater treatment at ambient temperature and proved the technical feasibility of this compartmentalised reactor. Considering its simple structure and operation, it could be considered a potential reactor system for treating municipal and domestic wastewaters in tropical and sub-tropical areas of developing countries.     

Dairy washwater treatment using a horizontal flow biofilm system

In Ireland, dairy farmyard washwater commonly comprises farmyard run-off and dairy parlour washings. Land-spreading is the most widely used method for treating this wastewater. However, this method can be labour intensive and can cause, in some cases, the degradation of surface and ground waters, mainly due to nitrogen contamination. In this study, a horizontal flow biofilm reactor (HFBR) with step-feed was constructed and tested in the laboratory, to remove organic carbon and nitrogen from a agricultural strength synthetic washwater (SWW). The HFBR had an average top plan surface area (TPSA) of 0.1002 m(2) and consisted of a stack of 45 polystyrene horizontal sheets--15 sheets embedded with 25 mm deep frustums above 30 sheets with 10 mm deep frustums. The frustums acted as miniature reservoirs. The sheets were alternately offset to allow the wastewater to flow horizontally along each sheet and vertically from sheet to sheet down through the reactor. Biofilms developed on the sheets and treated the wastewater. During the 212-d study, the total hydraulic loading rate based on the TPSA of the sheets was 35 l m(-2) d(-1). SWW was pumped for 10 min each hour, in a step feed arrangement at a rate of 23.33 l m(-2) d(-1) on to the top sheet during Phases 1 and 2, and 11.67 l m(-2) d(-1) onto Sheet 16 during Phase 1 (days 1-92) and onto Sheet 30 during Phase 2 (days 93-212). The substrate loading rate during Phases 1 and 2 was 94.8 g total chemical oxygen demand (COD) m(-2) d(-1) and 10.5 g total nitrogen (TN) m(-2) d(-1), based on the TPSA. At steady state in Phase 2, the unit achieved excellent carbon removal of 99.7% 5-day biochemical oxygen demand (BOD(5)) and 96.7% total COD, equivalent to TPSA removal rates of 67.5 g BOD(5)m(-2)d(-1) and 91.7 g COD m(-2) d(-1). The nitrogen removal percentages were 98.3% total ammonium-nitrogen (NH(4)-N(t)) and 72.8% TN, which equated to TPSA removal rates of 4.8 g NH(4)-N(t) m(-2) d(-1) and 7.6g TN m(-2) d(-1). No sloughing of solids or clogging of media occurred during the study. The unit was simple to construct and operate, with little maintenance.