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1.
Antibiotic contamination of aqueous environment due to pharmaceutical sewage may lead to development of antibiotic-resistant bacteria strain. In this research, elimination of antibiotics from synthetic wastewater was investigated. For this purpose, sulfamethoxazole and trimethoprim were treated by a pilot scale of net-like rotating biological contactor with three compartments, 48 plastic discs with total volume of 78.75 L. This system was continuously operated for about one year at various organic loading rates with different antibiotic dosages. The obtained results indicated that by increasing hydraulic retention time, the chemical oxygen demand (COD) removal was gradually increased. The optimal hydraulic retention time for desired rate of COD removal was 36 h. In addition, the effect of hydraulic retention time, organic load rate and sulfamethoxazole concentration in the removal of sulfamethoxazole and organic matter was assessed. Moreover, the results demonstrated that with increasing in organic load rate, sulfamethoxazole elimination was enhanced. In the next step, simultaneous removal of both antibiotics for constant inlet COD concentration of 8000 mg/L at optimum hydraulic retention time was analysed. The results showed that trimethoprim removal efficiency was approximately 100%, even at high concentration of trimethoprim (50 mg/L). For observation of dominant microorganism, samples of the developed biofilm on rotating biological contactor discs were scanned by scanning electron microscopy. In the first compartment where biomass was exposed to highest concentration of antibiotics, fungus strains were the dominant organism. In the second and third compartment antibiotic-resistant bacteria were the dominant attached living organisms.  相似文献   

2.
Denitrification of groundwater was studied using a laboratory-scale reactor packed with biodegradable snack ware served as both carbon source and biofilm support for microorganisms. The complete removal of 50 mg/L of nitrate-nitrogen was achieved in a 23-day-old reactor with 2.1 h of hydraulic retention time without inoculating with any external microorganisms, which indicates that indigenous microorganisms in groundwater proliferate readily and result in stable biofilm formation onto biodegradable snack ware. Accumulation of nitrite and nitrate residue was detected when hydraulic retention time was lower than 2.1 h. The breakthrough of nitrate-nitrogen up to over 10 mg/L in the effluent water was observed with nitrate removal efficiency reducing to about 75 % when hydraulic retention time was lowered to 1.4 h. The highest rate of denitrification was observed with 1.5 h of hydraulic retention time. Dissolved organic carbon concentration in the effluent water ranged between 10 and 20 mg/L during the stable operation of the reactor, and nitrite-nitrogen concentration was never higher than 0.09 mg/L. Considering its relatively low price and high denitrification rate, biodegradable snack ware can become a good alternative for denitrification process.  相似文献   

3.
吗啉废水的生化处理工艺   总被引：2，自引：0，他引：2  
以含有吗啉、甲基吗啉的高浓度有机废水为研究对象,提出了曝气吹脱-吸附-生物处理的联合工艺,并在室内进行了小试实验。结果表明：原废水经过2次曝气吹脱后,ρ(NH3-N)从62 500 mg/L降为431 mg/L,ρ(COD)从50 840 mg/L降为26 051 mg/L。通过吸附实验,ρ(COD)从26 051 mg/L降为2 769 mg/L,ρ(NH3-N)从412 mg/L降为134 mg/L。在生物处理室内小试实验中,采用了活性污泥反应器与曝气生物滤池相结合的处理工艺。在活性污泥反应系统中,当废水pH为7.5、ρ(DO)为4.3 mg/L、水力停留时间为30 h时,COD的去除率最高,可以达到83.1%。在曝气生物滤池中,当ρ(DO)为3.3 mg/L时,COD去除率最高,达到55.8%。在生物处理的最佳参数条件下进行连续监测,当进水ρ(COD)为2 769 mg/L、出水ρ(COD)平均值为387 mg/L时,COD去除率可达到85.9%。吗啉废水经过此联合工艺的处理,ρ(COD)从50 840 mg/L降为387 mg/L。  相似文献   

4.
A pilot scale study was set up to investigate the principle design parameters of up flow anaerobic sludge blanket (UASB) reactors for treating wastewater of small communities in the tropical regions of Iran. A steel pipe with a diameter of 600 mm and a height of 3.6 m was used as the reactor in which a digestion and a 3-phase separator element had a volume of 0.848 and 0.17 m3 respectively. During this study, which lasted for 203 days, two distinct phases were carried out according to the ambient temperature. The temperature of the wastewater entering the reactor was naturally ranged from 22 to 26 °C and no heat exchanger was used. The hydraulic retention times including 2, 4, 6, 8, and 10 hours with various loading rates of 0.95 to 5.70 kg COD/m3/day for colder period and from 1.35 to 6.40 kg COD/m3/day for warmer period were examined. On the basis of the results the optimal hydraulic retention time for warmer period with a 2.20 kg COD/m3/day organic loading rate was 6 hours which BOD5, COD and TSS removal efficiency were 71, 63 and 65 percent respectively. During the colder period the removal ratio of BOD5, COD and TSS with an optimal hydraulic retention time of 8 hours and organic loading rate of 1.22 kg COD/m3/day were 54, 46 and 53 percent respectively.  相似文献   

5.
A considerable increase in nitrate concentration in groundwater has been observed in many countries. This research focuses on nitrate removal using biodegradable snack ware (BSW) as both carbon source and biofilm support for denitrifiers. The denitrification efficiency of a laboratory-scale denitrification reactor packed with BSW was examined in a low-temperature condition. The nitrate removal efficiency supported by BSW decreased to approximately 40% at 12°C from nearly 100% at 25°C with 50?mg/L of nitrate-nitrogen in the influent and 2?h of hydraulic retention time (HRT). The complete nitrate removal was obtained when nitrate-nitrogen concentration was no more than 15?mg/L at 2?h of HRT and at 12°C. If the initial concentration of nitrate-nitrogen was 50?mg/L, 5?h of HRT was needed for the complete nitrate removal. Nitrite concentration in the treated water decreased evidently as HRT was increased from 2 to 5?h, or as nitrate-nitrogen concentration in the influent decreased to 15?mg/L from 50?mg/L. It was observed that varying HRT and nitrate concentration in the influent had no noticeable effect on dissolved organic carbon content in the effluent under the experimental conditions. This study indicated that the complete nitrate removal could be achieved readily even at 12°C using BSW as carbon source by changing HRT or the initial concentration of nitrate in the influent, which has some useful implications in environmental engineering practice.  相似文献   

6.
采用一套新型生物组合工艺(CSTR产酸发酵反应罐-UASBAF复合厌氧反应池-NMBR新型多级环流膜生物反应器)处理玉米深加工企业生产废水。研究结果表明:经过50d的启动期后系统进入稳定运行阶段,在稳定运行的155d内,组合工艺对COD和BOD的去除率高达99.4%和99.8%。基于厌氧消化数学模型(ADM1)和活性污泥数学模型(ASM1)对本组合工艺进行数学模拟研究,结果表明,该模型对每个工艺的出水COD预测平均误差均在15%以内,表明该模型对这套新型工艺具有很好的预测效果。  相似文献   

7.
Water supply for consumption is one of the crucial objectives of water supply systems. Using of excessive fertilizer is a main source of nitrate content in water. The high amounts of nitrate in water have a determinable effect on the environment which must be removed due to drinking and industrial water standards. The purpose of this study is nitrate removal from aqueous solution by Electrocoagulation process. The applied pilot was comprised of a reservoir, electrode and power supply. In this study pH, electrical potential difference, nitrate initial concentration, total dissolved solid, kind of electrode, electrode connection methods and number of electrode were studied. Moreover, obtained optimum conditions were tested on Kerman water. The results showed that the electrocoagulation process can reach nitrate to less than standard limit. pH, electrical potential difference, total dissolved solids and number of electrodes have direct effect and initial concentration of nitrate has reverse effect on nitrate removal. This study also showed that under optimum condition, nitrate removal from Kerman water distribution system was 89.7 %. According to the results, Electrocoagulation process is suggested as an effective technique in nitrate removal.  相似文献   

8.
In this research, a novel laboratory scale anaerobic/upflow sludge blanket filtration combined bioreactor was designed and operated to improve the efficiency of the upflow sludge blanket filtration process for the simultaneous removal of phosphorus and nitrogen from wastewater. The anaerobic/upflow sludge blanket filtration technique was developed by adding an anaerobic reactor to its influent and operated by varying the main process parameters in order to gain the optimum conditions. The results showed that biological removal efficiency of nitrogen and preservation of sludge blanket strongly depend on wastewater characteristics, hydraulic retention time, sludge age and process controlling parameters. The combined bioreactor performed a total nitrogen removal efficiency of 96.6 % with the sludge age of 25 days, total hydraulic retention time of 24 h and optimum “chemical oxygen demand/nitrogen/phosphorus” ratio of 100/ 5/1. This ratio also improved the compaction quality of sludge blanket in the upflow sludge blanket filtration clarifier. The average specific nitrification and denitrification rates occurred during the process can be expressed as 4.43 mg NOx-N produced/g VSS.d and 5.50 mg NOx-N removed/g VSS.d at the optimum ratio, respectively. To avoid sludge rising due to denitrification process, the optimum total hydraulic retention time of 16 to 24 h was achieved based on the effluent quality. This study suggested that the anaerobic/upflow sludge blanket filtration bioreactor at the optimum operational conditions can be an effective process for removal of nutrients from municipal wastewater.  相似文献   

9.
The study focused on the feasibility of high NH4 +–N (400–600 mg/L) and COD load at two different hydraulic retention times (HRTs = 36 and 24 h) in two identical aerobic–anoxic sequencing bioreactors which were constructed in series in a single system using a specifically designed single biomass containing autotrophic nitrifying and heterotrophic denitrifying bacteria. Internal recirculation of synthetic wastewater from one tank to other was not carried out like the conventional aerobic–anoxic processes. Cycles of 15 days under sequences of aerated and non-aerated periods of three hour each were repeated during each continuous flow experiment conducted. Sodium bicarbonate and sodium acetate were selected as the appropriate inorganic and organic carbon sources. The results showed that the HRT may not affect the simultaneous nitrification and denitrification processes. Average nitrification ratio was obtained to be above 20 mg/L NH4 +–N/h daily. Results of 90 days’ operation also showed high removal efficiencies of ammoniacal nitrogen of about 83% daily. The main advantage of this process includes efficient ammoniacal nitrogen removal without separated aerobic and anoxic tanks, decrease operating costs due to the lesser oxygen concentration requirement in the bioreactors.  相似文献   

10.
Wastewater treatment using moving bed membrane bioreactor technology was tested with real urban wastewater at a pilot plant, combining moving bed treatment as a biological process with hybrid biomass (suspended and fixed) and the advantages of a membrane separation system. The evolution of the kinetic constants of the hybrid biomass and organic matter removal were studied in a pilot plant under different operational conditions, by varying hydraulic retention time (HRT), mixed liquor suspended solids (MLSS) and temperature, and considering the attached biomass of the carrier and the dispersed biomass of the flocs to reproduce real treatment conditions. The rates of organic matter removal were 97.73 ± 0.81 % of biochemical oxygen demand (BOD5), 93.44 ± 2.13 % of chemical oxygen demand (COD), 94.41 ± 2.26 % of BOD5 and 87.62 ± 2.47 % of COD using 24.00 ± 0.39 and 10.00 ± 0.07 h of HRT, respectively. The influence of the environmental variables and operational conditions on kinetic constants was studied; it was determined that the most influential variable for the decay coefficient for heterotrophic biomass was HRT (0.34 ± 0.14 and 0.31 ± 0.10 days?1 with 10.00 ± 0.07 and 24.00 ± 0.39 h of HRT, respectively), while for heterotrophic biomass yield, this was temperature (0.61 ± 0.04 and 0.52 ± 0.06 with 10.00 ± 0.07 and 24.00 ± 0.39 h of HRT, respectively). The results show that introducing carriers in an MBR system provides similar results for organic matter removal, but with a lower concentration of MLSS.  相似文献   

11.
Acid Mine Drainage (AMD) needs to be treated before it can be re-used or discharged in receiving water bodies due to the low pH, high salinity and high sulphate concentrations of the water. Several treatment methods are currently applied including chemical treatment (e.g. neutralisation of the low pH waters), physical treatment (e.g. reverse osmosis) and biological treatment to reduce the high sulphate concentration. When treating AMD biologically, sulphate reducing bacteria (SRB) reduce sulphate to sulphide, provided that a suitable and cost effective carbon and energy source is present. In the present study mine water was remediated biologically, using the degradation products of grass-cellulose, as carbon and energy sources for the sulphate reducing bacteria. A laboratory scale one stage anaerobic bioreactor (20 L volume) containing grass cuttings and biomass consisting of rumen fluid microorganisms and immobilized SRB, was initially fed with synthetic sulphate rich water and later with diluted AMD. The results indicated an average of 86% sulphate removal efficiency when feeding synthetic sulphate rich feed water to the reactor. When feeding diluted AMD, the highest sulphate removal efficiency was 78%. The sulphate removal was dependant on Chemical Oxygen Demand (COD) concentrations in the reactor. Increased COD concentrations were obtained when fresh grass was added to the reactor on a regular basis. Metal removal, especially iron, was observed due to the metal sulphide precipitates formed during biological sulphate removal.  相似文献   

12.
采用PAC(聚合氯化铝)与PFS(聚合硫酸铁)混凝剂处理污水，并进行了对比实验。结果表明。在污水COD浓度为920mg／L，PFS折算为Fe2O3的投加量为300mg／L，pH为9．0时，出水COD为406mg／L，COD去除率为55．8％，而PAC折算为Al2O3的投加量为120mg／L时，出水COD为369．8mg／L，COD去除率为59．8％。PAC较PFS对COD的去除率高约4％。  相似文献   

13.
In this study, kinetics of biological carbon, nitrogen, and phosphorous removal from a synthetic wastewater in an integrated rotating biological contactor-activated sludge system was investigated. The experimental data obtained from varying four significant independent factors viz., hydraulic retention time, chemical oxygen demand for nitrogen to phosphorus ratio, internal recirculation from aerobic to anoxic zone and disks rotating speed were used for the process kinetic modeling. In order to obtain the bioprocess kinetic coefficients, Monod, first-order and Stover?CKincannon models were employed. As a result, Monod and Stover?CKincannon models were found to be the appropriate models to describe the bioprocess in the rotating biological contactor-activated sludge system as the determination coefficient for the first-order model obtained less than 0.79. According to the Monod model, growth yield, microbial decay rate, maximum specific biomass growth rate, and half-velocity constant coefficients were found to be 0.712?g VSS/g COD, 0.008/d, 5.54/d and 55?mg COD/L, respectively. From Stover?CKincannon model, the maximum total substrate removal rate constant and half-velocity constant were determined as 15.2, 10.98, 12.05?g/L?d and 14.78, 7.11, 6.97?mg/L for chemical oxygen demand, nitrogen and phosphorus removal, respectively. The kinetic parameters determined in this study can be used to improve the design and operation of the biological contactor-activated sludge system in full scale.  相似文献   

14.
Sewage treatment station in oilfield needs a new process to meet the desired requirements. A new process was proposed to meet the discharge standards, which consisted of the following sub-processes: electrochemical treatment → coagulation treatment → integrated biochemical treatment of moving bed biofilm reactor and membrane bio-reactor → combined treatment process of macroporous adsorption resin. Electrochemical treatment included 5 electrolytic cells, total volume of which was 10 L. The PFS was chosen as the coagulants in the coagulation treatment, and the removal rate of COD could reach 66% when the dosage of PFS was 500 mg/L. The biochemical treatment consisted of anoxic tank, aerobic tank and membrane zone, and the removal rate of COD was about 55–70% when HRT was 12 h. SD300 resin was chosen as the best adsorbent in the treatment using macroporous adsorption resin. In addition, the effluent COD after coagulation treatment process becomes about 180 mg/L, the effluent COD after biological treatment becomes about 50 mg/L, and the last effluent COD with the macroporous adsorption resin becomes about 20 mg/L. The three-dimensional fluorescence spectrum was used to analyze the differences in types of organic matters in water samples between the raw water and the treated one. The results demonstrated that the new process meets the needs of wastewater treatment.  相似文献   

15.
水泥系隔离墙被广泛应用于工业污染场地修复工程,但其防渗性能有待改善,且在高浓度、毒理性重金属污染作用下的化学相容性有待研究。通过室内试验研究了不同粒化高炉矿渣（GGBS）掺量、膨润土掺量和固化剂总掺量对水泥系隔离墙的强度和渗透特性的影响;综合考虑成墙效果和成本,选出固化剂掺量为20%（水泥、粒化高炉矿渣和膨润土掺量分别为8%、8%和4%）作为改性水泥系竖向隔离墙的最优配比。通过柔性壁渗透试验研究了重金属锌、铅污染作用下改性水泥系隔离墙试样的化学相容性。结果表明,重金属溶液作用下试样防渗性能的下降由重金属种类、重金属浓度以及试样孔隙液pH值三者共同决定。重金属种类对防渗性能的不利影响为：硝酸锌-硝酸铅>硝酸锌>硝酸铅。锌、铅溶液作用下试样的渗透系数为自来水作用下渗透系数的1.49～10.10倍,且重金属溶液的浓度越高渗透系数越大。在满足防渗要求前提下,该配比墙体材料能阻挡50 mmol/L的硝酸锌污染液、100 mmol/L的硝酸铅污染液和10 mmol/L硝酸锌-硝酸铅污染液。  相似文献   

16.
Laboratory scale studies were conducted in an up-flow anoxic bioreactor using synthetic fertilizer wastewater for ascertaining the denitrification efficiency. The performance of the reactor was compared using ethanol and topioca starch as the carbon source. The initial No3-N concentrations (50–250 mg/L) and hydraulic retention time (FTRT, 12–24 h) were varied to evaluate the COD and No3-N removal. The results from this study shows that ethanol gave very good denitrification efficiency (78–98%) compared to topioca starch (68–96%).  相似文献   

17.
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18.
Considering the importance of groundwater resources in water-supply demands in arid and semiarid areas such as Iran, it is essential to investigate the risk of groundwater pollution. Nitrate is one of the main pollutants that penetrate into the groundwater from various sources such as chemical fertilizers, pesticides, and domestic and industrial sewage. Unfortunately currently, nitrate contamination of the aquifers is a serious problem in Iran. The Karaj aquifer is not exempted, and the nitrate pollution zone, with concentrations far beyond the permitted limit (50 mg/L), expands fast. In this paper, the long-term groundwater-quality data (from 2000 to 2013) collected from Alborz Province Water and Wastewater Company were analyzed using ArcGIS10 and statistical software, and the spatial and temporal patterns of nitrate pollution in drinking-water wells in the Karaj plain and effective parameters (such as depth to groundwater level, hydraulic gradient, land use, precipitation, and urban, agricultural and industrial wastewater) were investigated. The authors also investigated the status of nitrate concentration variation using the concepts of geostatistics, based on determinations from 62 to 194 surveyed wells with a suitable distribution across the plain. With respect to the relationship between quality parameters, hydrogeological status of the aquifer and land usage, causes of the increase in the concentration of nitrate in the water and its trend were investigated as well. Results revealed that the nitrate levels in the northern portion of the study area were the highest with maximum concentrations of 181.7 mg/L from 2000 to 2013. Based on nitrate concentration distribution maps, the levels of nitrate increased from 2006 onwards to 26–100 mg/L. Unfortunately from 2008 to 2012, a pollution zone with a nitrate water concentration of 101–150 mg/L has been observed and even a concentration of 180 mg/L has been determined. In 2000, the entire aquifer area has been drinkable but with the increase in nitrate concentration, the area with undrinkable water has expanded to 21% in 2003, 24% in 2005, 33% in 2007, 39% in 2009, 43% in 2011 and 44% in 2013. The results of this study could provide valuable information with on the status of nitrate water concentrations in the Karaj plain which demands proper strategies and qualitative approaches in the future.  相似文献   

19.
Exposure to high concentration of nitrate through drinking water poses a threat to human health and environment. Electrocoagulation (EC) is an alternative water treatment process that involves electrogeneration of coagulant agents. In the present study, EC was exerted for the nitrate removal in a batch reactor using aluminum and iron anodes simultaneously. The effects of the main parameters including electrical current, initial pH, NaCl dosage, initial nitrate concentration and presence of turbidity on NO3 ? removal were investigated. NO2 ? as a by-product was monitored during electrolysis, and nitrate–nitrite index was calculated. The results indicated that optimum condition was pH of 5, 300 mA electrical current, 100 mg/L NaCl and electrolysis time of 40 min, under which removal efficiency was 81.5 %. Nitrite anion was generated during electrolysis of nitrate solution which increases nitrate–nitrite index at the first reaction time, and it was eliminated after 20-min electrolysis time. Reaction kinetic of nitrate removal in the absence and presence of turbidity was first-order and zero-order, respectively.  相似文献   

20.
As a common pollutant in groundwater, nitrate poses a significant threat to drinking water safety, especially in rural areas. A feasible solution to this problem must be established. In this study, a simple sand bucket was designed to investigate the capability of denitrification with liquor as the carbon source to remove nitrate from pumped groundwater, and the feasibility of the pump-and-treat method. Results showed that addition of a proper amount of liquor enhanced the growth and metabolism of denitrifying bacteria, efficiently reduced the nitrate content in pumped groundwater, and restricted the accumulation of intermediate products. The removal rate of nitrate exceeded 99% and reached about 16.0 mg/L/day when the carbon-to-nitrogen (C/N) ratio was higher than 0.8. The accumulated concentration of nitrite as an intermediate was less than 1.0 mg/L when the C/N ratio was higher than 1.5. However, acetate accumulation was significant. Considering the accumulation of intermediates, the appropriate range of the C/N ratio should be 1.5–1.8. In addition, onset and maintenance of denitrification were not significantly influenced by dissolved oxygen and pH. The pump-and-treat method can provide a convenient and practical channel for household or collective removal of nitrate from pumped groundwater in rural areas because liquor as a household drink is frequently accessible and inexpensive in many areas.  相似文献   

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