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Showing 7 results for Municipal Wastewater
Investigation of PHA Polymer Production from Sludge of Municipal Wastewater Treatment Plant and Its Effect on Sludge Volume Reduction
M Meschi Nezami, H Ganjidoust, N Mokhtarani, B Ayati,
Volume 3, Issue 4 (1-2011)
Abstract

Backgrounds and Objectives:Owing to the fact that the major environmental problem is production of surplus sludge in wastewater treatment plant, reducing the volume of produced sludge was objective of this research.
Materials and Methods: An anaerobic-aerobic SBR with working volume of 10 L was used to make micro-organism adapted and a polymer production reactor (PPR) with working volume of 1.5 L was used for producing polymer munisipal wastewater which contained different concentration of volatile fatty acids was consodered as the feed source (acetate and propionate) and this system was evaluated with SRT of 5, 7 and 10 days.
Results: The maximum polymer production efficiency observed within 5 days (SRT=5 days) though this efficiency was not significant in comparison with the two others time courses study. In this research the maximum polymer production efficiency at optimum condition was 25% of the sludge dry weight.
Conclusion: Experiment revealed that producing polymer from activated sludge reduced the volume of sludge and the maximum reduced sludge volume was obtained 19%.


The Compare Improvement of Ultrasonic  Treatment to Dewatering and Digestion in Aerobic  and Anaerobic Stabilization
Mahdi Kargar, Amir Hossein Mahvi,
Volume 5, Issue 1 (4-2012)
Abstract
A MicrosoftInternetExplorer4 Backgrounds and Objectives: Large quantities of sludge are produced in biological wastewater treatment. Because this sludge is highly rotten, it should be stabilized before its disposal. Aerobic and anaerobic digestion is widely considered as stabilization techniques. Because of high retention time and sludge dewatering difficulties, reduction in retention time, operation and maintenance should be given into consideration. Ultrasonic process increases the enzymatic activity, so decreases the hydrolysis time, a limiting factor in digestion process, and contributes to the decrease of the detention time. The objective of this investigation is to determine the effect of ultrasound in improving dewatering and stabilization of aerobic and anaerobic digested sludge. In addition, the impact of ultrasonic treatment on improvement of sludge dewatering and aerobic and anaerobic digestion is compared.
Materials and Methods: In this survey, samples of aerobic and anaerobic digestion were collected from local full-scale Garb Town and Tehran South wastewater treatment plant, respectively. The grab samples were collected for 4 month from July to October 2010. Total numbers of 20 samples were collected biweekly for each type of digestion. Each sample was sonicated for 15, 30, 60, and 90 min under 35 and 131 kHz frequencies separately. Total solids, volatile solids , pH, temperature , total COD, dissolved COD and settle able solids were measured. Ultrasound bath of the solution in a 300 mL glass reactor was performed as a bath reactor with power of 500 W.
Result: The results showed that the application of ultrasonic wave increased dissolved COD and temperature and decreased volatile solid, pH and settle able solids. Application of ultrasonic wave with frequency of 131 kHz decreased the VS and increased the dewatering of sludge more effective than the 35 kHz frequency and the highest performance was at 15 min of time and 131 kHz of frequency. Also sonication method showed better efficiency for anaerobic sludge samples compared to the aerobic sludge samples.                 
Conclusion: The results obtained showed that digestion and dewatering properties of sludge improved by ultrasonic application. Therefore it can be used as an alternative method for the sludge treatment.

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Performance Evaluation of Fixed and Rotating Bed Anaerobic Baffled Reactors for Municipal Wastewater Treatment
M Aqanaghad, G Moussavi,
Volume 9, Issue 3 (12-2016)
Abstract

Background and Objective: Being low cost of building and operation, anaerobic baffled reactor is considered superior to aerobic methods of wastewater treatment, especially for small communities. However, it needs to be studded for upgrade and overcome of its limitations. The purpose of this study was to evaluate the performance of FABR and RABR reactors for the municipal wastewater treatment at laboratory scale and in field conditions to determine their optimum conditions in reaching effluent discharge standards.

Materials and Methods: This study was conducted in Khoy wastewater treatment plant. FABR was operated for 267 days with hydraulic retention time of 18-48 h and RABR was operated for 90 days with media bad rotation of 10-50 rpm. The reactors were fed in line from the wastewater canal. Using composite sampling, 224 samples were taken from the inflow and outflow of the reactors and each sample was analyzed for parameters of COD, BOD, TSS, VSS, TKN, and TP.

Results: The reactor startup took about 107 days. FABR removal efficiency was 93-80, 21-10, and 30-21% for COD, TKN, and PO4 respectively at HRT of 48-18 h. FABR reached effluent disposal standard of TSS, COD, and BOD in all conditions and optimum HRT of 36 h. RABR reached to these standards at HRT 24 h and 50 rpm. However, none of them could meet the nutrient effluent standards.

Conclusion: FABR is an appropriate system for municipal wastewater treatment but for reaching N and P effluent standard, it should be combined with aerobic post-treatment. Moreover, in order to reuse the reactor's nutrient-rich effluent for irrigation; it can be reused as subsurface irrigation.


Pretreatment of municipal biological sludge by ultrasonic process: efficiency in hydrolysis, stabilization, and dewatering
R Barati Rashvanlou, M Farzadkia,
Volume 11, Issue 1 (6-2018)
Abstract
Background and Objective: Ultrasonic disintegration is a pretreatment process before stabilization and dewatering that degrades sludge and changes its physical and chemical characteristics. The aim of this study was to investigate the effectiveness of ultrasonic in enhancing hydrolyses, stabilization and dewatering of municipal raw activated sludge.
Materials and Methods:  The samples were taken from returned activated sludge and then they were exposed to ultrasonic (Frequency: 20 and 40 kHz) in different times (0.5, 1, 3, 5, 10, 15, 30, and 60 min). The effectiveness of ultrasonic for hydrolysis, stabilization and dewatering processes were determined with measuring TS, TSS, CST, SRF, VS, nVS, VSss, and VSsol.
Results: VSsol was increased by 73% in 15 min and at frequency of 20 kHz, whereas VSsol increas was100% at 10 min and 40 kHz. The reduction of VS was observed at 15 min and 20 kHz. Then after, it was reached 18% after 60 min. For 40 kHz, VS reduction started at 10 min and reached 24% after 60 min. Specific resistance of sludge at two frequencies of 20 and 40 kHz and contact time of 1 min were decreased by 25 and 20% respectively. The capillary suction time at the frequencies of 20 and 40 kHz and contact time of 1 min was decreased 28 and 21%, respectively.
Conclusion: The optimum effectiveness of ultrasonic in hydrolysis of organic matter of raw biological sludge was at the contact time of 10 min and frequency of 40 kHz. The highest stabilization at the frequency of 40 kHz was observed at 60 min contact time. The best condition for sludge dewatering was at frequency of 20 kHz and contact time of 1 min.
 

Performance evaluation of modified up flow septic tanks reactor for treatment of synthetic wastewater
Mohsen Ansari, Mahdi Farzadkia,
Volume 13, Issue 1 (4-2020)
Abstract
Background and Objective: Considering 829000 annual diarrhoeal deaths due to water pollution worldwide, the World Health Organization has emphasized that countries should reduce this rate by upgrading their wastewater treatment systems. The purpose of this study was to evaluate the performance of a modified up flow septic tanks reactor for treatment of synthetic wastewater.
Materials and Methods: In this experimental study, a modified septic tank system based on the upstream hydraulic regime, and also a conventional septic tank system was designed, manufactured, and operated. The municipal wastewater was used to operate, and synthetic wastewater was used to maintain. The major performance indicators of septic tanks include: volatile solids (VS), volatile suspended solids (VSS), total suspended solids (TSS) and chemical oxygen demand (COD) were sampled and measured in triplicates. The experiments were done in three hydraulic retention times of 24, 48, and 72 hr. Finally, the results of the study were analyzed by statistical tests in the SPSS software.
Results: The average removal of TSS, VS, VSS, and COD in HRT 24 h for the conventional reactor were 55.07, 27.36, 30.82, and 55.52%, respectively, and for the upstream-modified reactor at HRT 24 h were 66.57%, 34.05%, 38.47%, and 65.57%, respectively.
Conclusion: Changing septic tanks to up flow regimes and creating a cylindrical shape in conventional septic tanks, the removal efficiency of conventional septic tanks was improved, and the effluent contamination load was reduced.
Evaluation of pre-treatment efficiency of fats, oils and greases using low frequency ultrasonic waves to accelerate the process of anaerobic digestion
Reza Barati Rashvanlou, Mahdi Farzadkia, Abbas Ali Moserzadeh,
Volume 14, Issue 1 (5-2021)
Abstract
Background and Objective: Hydrolysis of fat, oil and grease by ultrasonic waves is a pre-treatment method before anaerobic digestion which can change their physical, chemical and biological properties. The main purpose of this study was to investigate the efficiency of ultrasonic waves to improve the hydrolysis process and its use as an auxiliary substrate to increase the efficiency of anaerobic digestion process along with municipal sewage sludge.
Materials and Methods: Sampling of fat and oil of the degreasing unit and physical preparation by conducting ultrasonic waves with frequencies of 20 kHz and current density of 0.012-0.14 W/mL within 0-12 min were performed. The efficiency of pretreatment process were performed through tests such as soluble chemical oxygen demand (SCOD), and lipase enzyme activity. In addition, the anaerobic digestion process were evaluated by measuring the TS, VS, VA (volatile acidity), alkalinity, biogas production and biogas methane content.
Results: The results showed that the highest increase in the activity of lipase enzyme under ultrasonic effect with a power of 0.1 w/mL was obtained after 8 minutes. Organic loading with 10%, 20% and 40% FOG/MSS ratios: resulted in 55%, 66% and 64% increase in methane production compared to the control samples, respectively. Organic loading over the 40% FOG/MSS caused a limitation in the simultaneous digestion process.
Conclusion: The results show that ultrasonic wave pretreatment with optimal power and time can improve the hydrolysis of TFOG while increasing the activity of lipase enzyme and also its use as an auxiliary substrate can enhance digestion performance and make digestion more stable.

Feasibility of treating the produced sludge in municipal wastewater treatment plant using ozonation method
Mohsen Ansari, Mahdi Farzadkia,
Volume 14, Issue 2 (9-2021)
Abstract
Background and Objective: Wastewater treatment and stabilization always imposes costs and consequently a lot of energy on wastewater treatment plants. To achieve the purification and stabilization of as much sludge as possible, breaking complex components into simpler components is considered a critical step. Therefore, this study aimed to evaluate the feasibility of treating the produced sludge in the municipal wastewater treatment plant using ozonation method.
Materials and Methods: In this study, sludge was obtained from the return line of activated sludge from the wastewater treatment plant in the south of Tehran. An ozonation generator with a discharge rate of 3 L/min and an ozone concentration of 40-35 mg/L was discharged to the reactor and the residual ozone concentration was measured by iodometric method. Finally, the total suspended solids and volatile, soluble chemical oxygen demand, total organic carbon, and biochemical oxygen demand during ozonation processes were measured using the Standard Method.
Results: The results of this study showed that the amount of TSS and VSS in the activated return sludge decreased from 4060 to 2100 mg/L and from 3300 to 1850 mg/L during the ozonation process, respectively. However, SCOD, TOC, and SBOD had an upward trend of about 18, 11.7, and 14 times in the same reaction time, respectively.
Conclusion: According to the results of this study, it can be concluded that the ozonation system can be proposed as a suitable process for the decomposition of sludge produced in wastewater treatment plants and increasing the biodegradability of these sludges.

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