ABSTRACT
Introduction: The Powdered Activated Carbon Treatment [PACT] has been proposed as an alternative in wastewater treatment and wastewater biomass protection against toxic substances. This study aims to evaluate PACT performance in treating dyes, acid orange, and remazol brilliant reactive blue
Materials and Methods: This empirical- applied research was carried out in pilot scale in which different dye removal systems were tested: activated sludge, PAC, and the combined activated carbon-biomass system. The degradability of selected dyes was evaluated through Zahn-Wellens method. Also, tests continued by adding different concentrations of powdered activated carbon and it's effect on activated sludge in different operating conditions was investigated. American Dye Manufacture Institute [ADMI] method was utilized for determination of dye removal in samples
Results: Results revealed that dye removal in combined carbon-biomass system was faster and more efficient than activated sludge individually. So, in the wastewater with the dye concentration of 100 ppm, the dye removals through biological process alone were equal to 60 % and 12.5 % for acidic and reactive dyes, respectively. The best PAC efficiency in activated sludge process was obtained in 1500 mg/L PAC concentration. Hydraulic Retention Time [HRT] and the optimum temperature of dyes' removal were determined 28 hours and 30 [degree sign], orderly; in these conditions the dye removal efficiency of 98.18 % was obtained. Also the dye removal using activated carbon-biomass system was adequately described by combining the kinetic equations
Conclusion: PACT could be considered as an acceptable and highly efficient method for removal of different dyes in textile industry
ABSTRACT
Background: This study assessed the removal of organic material and nutrients from full-scale subsurface flow [SSF] constructed wetlands [CWs] followed by anaerobic stabilization ponds under environmental conditions
Methods: The effluents were distributed evenly in 12 reed beds. Samples were taken twice monthly for a total of 6 months from several points in the wetland. Biochemical oxygen demand [BOD], chemical oxygen demand [COD], total suspended solids [TSS], and nutrient removal from the system and the longitudinal effect of the reed beds for removal of pollutions were determined. A full-scale model of flow, BOD, and nutrients in SSF in the CWs is presented
Results: The flow rate and concentrations of parameters indicated that removal of organic matter and nutrients in the cold months decreased rather than in the hot months, as expected. The removal efficiency for BOD, COD, and TSS and the strongest biological interactions showed no uniform trends. The beds showed the highest removal rates in the first few meters of bed. The hybrid Monod-Plug flow regime and the Stover-Kincannon models showed the best fit for the kinetics of the processes. U[max] in the Stover-Kincannon model was 3.64 mg/l.d for nitrogen and 0.24 mg/l.d for phosphorus. These values are very low, which indicates lower consumption and inefficiency of the system for removing nitrogen and phosphorus
Conclusion: It can be concluded that the SSF in CWs are able to treat average wastewater as effectively as common mechanical systems at lower cost
ABSTRACT
Background: Disintegration and dewatering of produced sludge during wastewater treatment is one of the main challenges in wastewater treatment process. The aim of this study is to investigate the efficiency of ultrasonic method on dewatering of bio sludge in wastewater treatment plant under different conditions and select the best conditions.
Materials and Methods: In the present study, sludge disintegration and sludge dewatering after undergoing different conditions of frequency [35 and 130 KHz] and detention time [3, 5, 10 and 30 min] were investigated and finally the changes of SCOD, CST and SRF were determined.
Results: The results illustrated that the maximum ability of dewatering was obtained at a detention time of 5 min and frequency of 35 KHz for ultrasonic. Under this conditions SCOD%, CST and SRF were achieved to 4.3%, 151 S and 2.1×1013 m/kg respectively.
Conclusion: According to the results, ultrasonic method significantly increases the sludge disintegration and improves the sludge dewatering.