Optimization of coagulation-flocculation process for dye and COD removal from real dyeing wastewater and evaluation of effluent biodegradability in a carpet factory

Background and Aim: Textile industry is one of the largest consumers of water in the world. The wastewater from the textile industry is known to have strong colour, chemical oxygen demand (COD), highly fluctuating pH and high temperature. The release of coloured wastewater represents a serious environmental and public health concern. Among the various physicochemical and biological methods of textile wastewater treatment, coagulationflocculation is considered as an attractive and favourable technique because of its low cost, easy operation and highefficiency.Materials and methods: The study was conducted in the laboratory scale using Jar test. Dye removal from real wastewater was investigated by the use of three mineral coagulants including poly aluminum chloride, ferric sulfate and ferric chloride. In order to optimize the process, parameters including pH, coagulant dose, time and speed of coagulation were considered. Treated samples were analysed to determine the residual color and COD.Results: According to the results of our experiments, under optimum conditions of process (pH 9, doses of 250 mg/lcoagulant and coagulation speed of 175 rpm with a duration of 5 minutes), the highest removal efficiencies (COD 44.4% and color 95%) were obtained by the use of poly aluminum chloride. The results showed that poly aluminum chloride enhanced the biodegradability of wastewater from 0.07 to 0.21 at optimized process conditions.Conclusion: Although the coagulation process reduced a large percentage of pollution load in the wastewater, another process has to be followed to meet the wastewater discharge standards in receiving sources.Keywords: Textile wastewater, Dye, Coagulation, Biodegradabilit

Performance of electrical stimulated anaerobic baffled reactor for removal of typical pollutants from low-strength municipal wastewater at low temperatures

Background: Although anaerobic system has been successfully used for treating the strong industrial wastewater, its efficiency for low-strength wastewater as municipal wastewater is not satisfying. This study aimed to enhance the capability of an anaerobic baffled reactor (ABR) for treating municipal wastewater. Methods: A 7-L ABR with 5 compartments was operated for a 287-day period fed with primary effluent from a wastewater treatment plant at 17 to 19°C. The study was conducted in 2 phases. In the first phase, the performance of ABR and in the second phase, the performance of ESABR (ABR integrated with an electrochemical system) were investigated. Results: The results of ABR operation indicated that at hydraulic retention time (HRT) =24 hours, the average removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorous (TP), and log reduction value (LRV) of coliforms were obtained to be 71%, 75%, 79%, 23%, 30.3%, and 5.8 Log, respectively. In this phase, when the HRT was decreased from 24 to 18 hours and from 18 to 14 hours, the removal efficiency of all parameters by the ABR was decreased. After the shift of ABR operation to ESABR, at HRT=24 hours and current density of 0.78 mA/cm2, the performance of the reactor was enhanced, so that the removal efficiency of BOD, COD, TSS, TKN, TP, and LRV of coliforms were achieved 16.8%, 15%, 4%, 10.7%, 49%, and 1 Log, which was greater than those obtained by ABR. Conclusion: According to the results, this technology (SEABR) is suitable for treating the low-strength municipal wastewater. Keywords: Wastewater, Anaerobic baffled reactor, Electrical stimulated, Treatmen

بهینه سازی فرآیند انعقاد جهت حذف COD و رنگ از فاضلاب واحد رنگرزی یک کارخانه فرش ماشینی و ارزیابی تجزیه پذیری بیولوژیکی پساب حاصل

Background and Aim: Textile industry is one of the largest consumers of water in the world. The wastewater from the textile industry is known to have strong colour, chemical oxygen demand (COD), highly fluctuating pH and high temperature. The release of coloured wastewater represents a serious environmental and public health concern. Among the various physicochemical and biological methods of textile wastewater treatment, coagulationflocculation is considered as an attractive and favourable technique because of its low cost, easy operation and highefficiency.Materials and methods: The study was conducted in the laboratory scale using Jar test. Dye removal from real wastewater was investigated by the use of three mineral coagulants including poly aluminum chloride, ferric sulfate and ferric chloride. In order to optimize the process, parameters including pH, coagulant dose, time and speed of coagulation were considered. Treated samples were analysed to determine the residual color and COD.Results: According to the results of our experiments, under optimum conditions of process (pH 9, doses of 250 mg/lcoagulant and coagulation speed of 175 rpm with a duration of 5 minutes), the highest removal efficiencies (COD 44.4% and color 95%) were obtained by the use of poly aluminum chloride. The results showed that poly aluminum chloride enhanced the biodegradability of wastewater from 0.07 to 0.21 at optimized process conditions.Conclusion: Although the coagulation process reduced a large percentage of pollution load in the wastewater, another process has to be followed to meet the wastewater discharge standards in receiving sources.زمينه و اهداف: صنعت نساجي يکي از بزرگترين مصرف کنندگان آب در جهان است که فاضلاب آن با مقادير زياد رنگ، اکسيژن مورد نياز شيميايي بالا، pH با نوسان زياد و درجه حرارت بالا شناخته شده است. در ميان روش‌هاي تصفيه فاضلاب صنايع نساجي، فرايند انعقاد به دليل راهبري ساده و اثربخش و همچنين هزينه سرمايه‌گذاري نسبتاً پايين به طور گسترده‌اي مورد استفاده قرار مي‌گيرد. مواد و روش‌ها: مطالعه در ﻣﻘﻴﺎس آزﻣﺎﻳﺸﮕﺎﻫﻲ بر روي نمونه واقعي و ﺑﺎ اﺳﺘﻔﺎده از سه ﻣﻨﻌﻘﺪ ﮐﻨﻨﺪه ﻣﻌﺪﻧﻲ ﭘﻠﻲ آﻟﻮﻣﻴﻨﻴﻢ ﮐﻠﺮاﻳﺪ، ﺳﻮﻟﻔﺎت ﻓﺮيک و ﮐﻠﺮورﻓﺮﻳﮏ با استفاده از دستگاه جارتست انجام شد. به منظور بهينه‌سازي فرآيند، متغيرهاي pH، غلظت ماده منعفد کننده، زمان و سرعت انعقاد در حذف رنگ و COD مورد بررسي قرار گرفت. تعيين  نسبت BOD5/ COD  به عنوان شاخص تجزيه پذيري استفاده شد. يافته‌ها: در شرايط بهينه فرآيند (pH برابر با 9، دوز 250 ميلي‌گرم بر ليتر و سرعت انعقاد 175 دور در دقيقه با زمان 5 دقيقه)، بيشترين مقادير راندمان حذف رنگ و اکسيژن مورد نياز شيميايي با کاربرد پلي آلومينيوم کلرايد به ترتيب 95 و 77/4 درصد حاصل شد. کاربرد منعقد کننده پلي آلومينيوم کلرايد در شرايط بهينه ميزان تجزيه پذيري فاضلاب را از 0/07 به 0/21 افزايش داد.  نتيجه‌گيري: اﮔﺮﭼﻪ ﻓﺮآﻳﻨﺪ اﻧﻌﻘﺎد، درﺻﺪ ﺑﺎﻻﻳﻰ از ﺑﺎر آﻟﻮدﮔﻰ ﻣﻮﺟﻮد در ﻓﺎﺿﻼب را ﻛﺎﻫﺶ ودرصد تجزيه پذيري را افزايش ﻣﻰ‌دﻫﺪ، اﻣﺎ تصفيه بيشتر پساب براي تخليه به محيط زيست ضروري  مي‌باشد

Evaluation of the effectiveness of electro-coagulation-flotation process for removal toxicity of olive oil mill wastewater

زمینه و اهداف: فاصلاب صنعت استخراج  روغن زیتون از آلوده کننده ترین فاصلاب های صنایع غذایی می باشند. فرایند استخراج روغن زیتون فاصلابی با بار آلودگی بالا از تکیبات شیمیایی فنلی به محیط وارد می کند که دارای خاصیت ضدباکتریایی بوده و برای گیاهان نیز سمی است. در این مطالعه سمیت فاضلاب خام صنعت روغن زیتون و فاضلاب تصفیه شده با فرایند انعقاد و شناورسازی الکتریکی با انجام تست جوانه زنی مورد ارزیابی قرار گرفته است. روش کار: آزمایشات جهت انجام فرایند انعقاد  شناورسازی در یک راکتور الکتروشیمیایی پلکسی گلاس به حجم  مفید 1750 میلی لیتر انجام گرفت. به منظور ارزیابی سمیت فاضلاب و پساب حاصل از فرایند نیز تست جوانه زنی مورد استفاده قرار گرفت. یافته ها: نتیاج نشان داد که بار آلودگی ترکیبات فنلی فاضلاب صنعت روغن کشی زیتون 1000 برابر بیشتر از فاضلاب شهری است. همچنین نتایج حاصل از ارزیابی سمیت پساب فرایند انعقاد و شناورسازی الکتریکی در شرایط پی اچ طبیعی فاضلاب دانسیته جریان 117 آمپر بر مترمربع و زمان فرایند 30دقیقع حاکی از آن است که پساب حاصل از این فرایند حتی بدون رقیق سازی رشد بذرهای گونه های گیاهی را به دنبال دارد. نتیجه گیری: نتایج حاصل از این تحقیق نشان دهنده میزان خطرات ناشی از رهاسازی بدون تصفیه این فاضلاب و اثرات سمیتی آن بر گون های مختلف گیاهی می باشد. با توجه به نتایج آزمایش های تعیین کیفیت پساب حاصل از فرایند انعقاد و شناورسازی الکتریکی، اگرچه این فرایند درصد بالایی از بار آلودگی موجود در فاضلاب را کاهش می دهد اما براساس استانداردهای تخلیه و همچنین استانداردهای آب کشاورزی تصفیه بیشتر حاصل از این فرایند ضروری است.Background: The olive oil mill wastewater is one of the contaminating food industrial wastewaters. Olive oil extraction process imports wastewater with high phenolic chemicals into the environment. In this study the toxicity of raw olive oil mill wastewater and the effluent of electro-coagulation have been investigated.Material & Methods: Germination test was used for evaluating the toxicity of wastewater and effluent process. Electro-coagulation-flotation examinations performed in a plexiglas electrochemical reactor with 1750 ml practical volume. 4 blades of aluminum and titanium as anode and cathode electrodes with a gap of 2 cm were connected to DC power supply in monopolar parallel mode.Results: Based on the information from this study, the pollution load of phenolic compounds in olive oil mill wastewater is 1000 times more than municipal wastewater. Also, the evaluation toxicity of effluent obtained from the process in natural pH of wastewater (pH=5.2), 117 mA/m2 current density and 30 minutes time process, suggests that the effluent causes plant species growth, even without dilution.Conclusion: The results obtained from this research can warn us to the risks of releasing these wastewaters without treatment and toxic effects on the different species of plants. Results demonstrated although using of electro-coagulation-flotation process removes high percent of pollutants of olive oil mill wastewater, but, it can’t attain the discharge limitations, then it should be more treated with some other methods