Biosorption and recovery of copper and zinc from aqueous solutions by nonliving biomass of marine brown algae of Sargassum sp.

In this study, the biosorption properties of a pre-treated nonliving biomass of marine brown algae of Sargassum species in the removal of Cu 2+ and Zn2+ ions were investigated. Kinetics, equilibrium isotherms, recovery of metals and regeneration of the Sargassum biomass were carried out under different laboratory conditions using batch reactor. Biosorption of Cu2+ and Zn2+ was rapidly occurred onto Sargassum biomass and most of the sorbed metal was bound in less than 60 min. The removal performance for Zn2+ by the biomass was found more than Cu2+, with maximum uptake values of 1.914 and 1.314 mg g-1 dry weight biomass for Zn2+ and Cu2+, respectively. Optimum biosorption pH value of Cu2+ and Zn2+ was determined as 5 at lab temperature. At the optimal condition, metal ion uptake increased with initial Cu2+ and Zn2+ concentration upto 200 and 500 mg L-1, respectively. The Cu2+ and Zn 2+ uptake by Sargassum biomass was best described by pseudo-second order rate equation. The results showed that the Freundlich isotherm model was suitable for describing the passive biosorption of Cu2+ and Zn 2+ by the dead biomass of Sargassum. Removal of the biosorbed Cu 2+ and Zn2+ from Sargassum biomass was successfully achieved by eluting with 0.1 M HNO3 for 15 min and a high degree of metal recovery was observed. For optimum operation in the subsequent metal uptake cycle, regeneration of the Sargassum biomass was efficiently performed by 0.1 M CaCl2 for 15 min. In repeated use of biomass experiment, the Cu2+ and Zn2+ uptake capacity of Sargassum biomass was approximately retained and no significant biomass change took place after three biosorption-desorption cycles. © 2006 Asian Network for Scientific Information

Biosorption and recovery of copper and zinc from aqueous solutions by nonliving biomass of marine brown algae of Sargassum sp.

In this study, the biosorption properties of a pre-treated nonliving biomass of marine brown algae of Sargassum species in the removal of Cu 2+ and Zn2+ ions were investigated. Kinetics, equilibrium isotherms, recovery of metals and regeneration of the Sargassum biomass were carried out under different laboratory conditions using batch reactor. Biosorption of Cu2+ and Zn2+ was rapidly occurred onto Sargassum biomass and most of the sorbed metal was bound in less than 60 min. The removal performance for Zn2+ by the biomass was found more than Cu2+, with maximum uptake values of 1.914 and 1.314 mg g-1 dry weight biomass for Zn2+ and Cu2+, respectively. Optimum biosorption pH value of Cu2+ and Zn2+ was determined as 5 at lab temperature. At the optimal condition, metal ion uptake increased with initial Cu2+ and Zn2+ concentration upto 200 and 500 mg L-1, respectively. The Cu2+ and Zn 2+ uptake by Sargassum biomass was best described by pseudo-second order rate equation. The results showed that the Freundlich isotherm model was suitable for describing the passive biosorption of Cu2+ and Zn 2+ by the dead biomass of Sargassum. Removal of the biosorbed Cu 2+ and Zn2+ from Sargassum biomass was successfully achieved by eluting with 0.1 M HNO3 for 15 min and a high degree of metal recovery was observed. For optimum operation in the subsequent metal uptake cycle, regeneration of the Sargassum biomass was efficiently performed by 0.1 M CaCl2 for 15 min. In repeated use of biomass experiment, the Cu2+ and Zn2+ uptake capacity of Sargassum biomass was approximately retained and no significant biomass change took place after three biosorption-desorption cycles. © 2006 Asian Network for Scientific Information

Toxicity Evaluation of Wastewater Treatment Plant Effluents Using Daphnia magna

Toxicity evaluation is an important parameter in wastewater quality monitoring as it provides the complete response of test organisms to all compounds in wastewater. The water flea Daphnia magna   straus is the most commonly used zooplankton in toxicological tests. The objective of this study was to evaluate the acute toxicity of effluents from different units of Isfahan Wastewater Treatment Plant (IWTP). The samples were taken from four different physical and biological units. The acute toxicity tests were determined using Daphnia magna. The immobility of Daphnia was determined after 48h. Toxicity results showed that 48h-LC50 and ATU values for raw wastewater were 30% (v/v) and 3.33, respectively. It was also found that LC50 values after 48 h for preliminary, primary, and secondary effluents were 32%, 52% and 85% (v/v), respectively. The ATU values for these effluents were 3.1, 1.9, and 1.8, correspondingly. The efficiency levels of preliminary, primary, and secondary units for removal of toxicity were found as 6%, 38.9% and 8%, in that order. Overall, the present investigation indicated that toxicity removal by up to 50% might be achieved in IWPT. Based on the obtained results and regarding the improvement of water quality standards, coupled with public expectations in Iran, it is necessary to consider more stringent water quality policies for regular monitoring and toxicity assessment

Effects of aeration rate and detention time on thermophilic aerobic digestion of mixed sludge and its dewaterability

Thermophilic aerobic digestion (TAD) is a possible alternative for rapid sludge degradation and producing Class A biosolids. Aeration rate and detention time are two of the important parameters in TAD processes due to rapidly growing thermophilic bacteria population, limited solubility of oxygen at high temperatures and the need to prevent cooling of TAD process. Also the current knowledge and understanding of dewatering TAD biosolids are limited and incompelet.The objectives of this study were to investigate the effects of various aeration rates and detention time on some characteristics of mixed sewage sludge. Four glass-cylindrical digesters with 7 liters of sludge in each, placed in a water bath and were operated at 55 °C with the aeration rates of 2.14, 3.00, 3.86 and 4.71 volume of air per volume of sludge per hours. It was found the increase in aeration rate decreased the required detention time in order to meet the Class A sludge regulations to reduce vector attraction. The values of Oxidation-Reduction Potential (ORP) were changed from negative values to positiv ones and the values of pH were increased from around neutral to slightly basic, but this increases were occured at different detention times. TAD affected dewaterability of mixed sewage sludge and produced biosolids with higher specific resistance to filtration (lower dewaterability) than undigested sludge. Thermophically digested sludge has a good setteling behavior and air drying on sand bed

STABILIZATION OF DEWATERED SEWAGE SLUDGE BY AEROBIC COMPOSTING METHOD: USING SAWDUST AS BULKING AGENTS

Introduction. Sludge production from municipal wastewater treatment plants should have quality standards before disposal in to the environment. Environmental specialists classified sewage sludge as a hazardous waste because of high organic compounds and pathogenic microorganisms. They belive that sewage should be stabilized before disposal and so composting of sewage sludge is an effective and economical method to stabilize. Sewage sludge compost could be used to improve soil structure and enrich the soil with nutrients.
 Methods. To evaluate the optimum conditions of aerobic compost, the mixture of dewatered sewage sludge from Isfahan municipal waste water treatment plant and sawdust as bulking agent were used. Pilot scale study were performed in Isfahan municipal waste water treatment plant. To perform this research project, the dewatered sewage sludge with humidity between 78 to 82 percent were mixed with sawdust. Turning over method of the piles with one week interval were applied to aerate the mixture. Temperature of the piles were monitored at different depths daily. Other parameters such as N, G, organic matters and pH were determined weekly. Total and fecal coli form, and salmonella were determined at the beginning and end of the composting process, also heavy metals were measured at the same time.
 Results. The results of this study showed that after days, temperature of the mixture reached up to 55 G, and were stabled for 15 days. Humidity, organic matter, organic carbon and GIN ratio of the mixture decreased over the period of the study, due to increasing the temperature. Also organic matter and humidity mainly decreased in thermofilic phase. The number of total and fecal coliform and also salmonella decreased to A class standards of US.EPA at the end of the operation.
 Discussion. The results of the study also showed that, this type of composting method is reliable, and simple to schedule, with high flexibility and low odor production. Organic compounds and pathogenic microorganisms reduced and EPA standards were reached during this project

Survey of Efficiency of Electrochemical Treatment in Cyanid Removal from Industrial Wastewatersrs

Background and Objectives: Cyanide is a highly toxic compound which is Normally found in numerous industries, such as electroplating wastewater. Release of this compounds in to the Enviroment has a lot health hazards.The Purpose of this study is to Determine the efficiency of electrochemical oxidation method for Cyanide removal from industrial wastewaters Materials and Methods: This study conducted in a pilot system experimentally .In this study the effect of pH, voltage and operation time on total cyanide removal from industrial wastewaters by Electrochemical Oxidation was investigated by applying a Stainless Steel as a Anode and copper as a cathode .Results: The average percentage removal of cyanide was about 88 with SD=2.43. The optimal condition obtained at voltage of 9V and pH=13 and The operation time of 90 minutes.The volume of sludge which formed in this condition was about 20 percent of a one liter pilot reactor.Conclusion: the results statistically confirmed the significant relationship between input and cyanide concentration removal efficiency (p< 0.05), and confirmed The this confirmed The relation between cyanide & cyanat oxidation and hydroxyl ions consumption 1:2.( L.Szpyruowicz). therefore the best pH is 12.5-13.5 by Considering the need of alkaline environment to remove cyanide.Background and Objectives: Cyanide is a highly toxic compound which is Normally found in numerous industries, such as electroplating wastewater. Release of this compounds in to the Enviroment has a lot health hazards.The Purpose of this study is to Determine the efficiency of electrochemical oxidation method for Cyanide removal from industrial wastewaters Materials and Methods: This study conducted in a pilot system experimentally .In this study the effect of pH, voltage and operation time on total cyanide removal from industrial wastewaters by Electrochemical Oxidation was investigated by applying a Stainless Steel as a Anode and copper as a cathode .Results: The average percentage removal of cyanide was about 88 with SD=2.43. The optimal condition obtained at voltage of 9V and pH=13 and The operation time of 90 minutes.The volume of sludge which formed in this condition was about 20 percent of a one liter pilot reactor.Conclusion: the results statistically confirmed the significant relationship between input and cyanide concentration removal efficiency (p< 0.05), and confirmed The this confirmed The relation between cyanide & cyanat oxidation and hydroxyl ions consumption 1:2.( L.Szpyruowicz). therefore the best pH is 12.5-13.5 by Considering the need of alkaline environment to remove cyanide