Survey of parasitic contamination of sewage sludges in northern Iran

The use of sewage sludge as fertilizer in agriculture is a convenient and economic solution, but it is essential to monitor presence of parasitic contamination. This study investigated parasites in sewage sludge of wastewater treatment plant in Gorgan, Iran. This descriptive-analytical study was performed on 18 sewage sludge samples collected from wastewater treatment plant of Gorgan within 6 months with three repeatitions per month. The samples were analyzed in the laboratory of School of Public Health at Golestan University of Medical Sciences. Analysis of parasites was done using Bailenger method of counting parasites in chamber of McMaster slides with volume of 0.3 ml. The results showed that majority of parasite eggs in the sewage sludge was related to nematodes. The dominant nematode eggs detected were related to Ancylostoma duodenale, Necator americanus and Enterobious vermicolaris. However, no parasite was found in dried sewage sludge. Considering the amount of parasite eggs in the returned sludge, it is necessary to modify the treatment process. However, it is permissible to use dried sewage sludge as agricultural fertilizer.Keywords: Parasite eggs, Protozoa, Sewage sludge, Ira

Heavy metal contamination in the effluent and sludges of wastewater treatment plant in Gorgan, Iran

Background and purpose: Environmental pollution by heavy metals and their transfer to soil and crops are a growing global problem. This study aimed to measure the concentrations of heavy metals in wastewater and sludge wastewater treatment plant in Gorgan, Iran. Materials and methods: In this cross-sectional study, 176 samples of effluent, and returned and dried sludges were analyzed in wastewater treatment plant in Gorgan, during six months in 2016. The concentration of Pb, Cd, Ni, and Cr were determined using polarography (Metrohm797 AV) and furnace atomic adsorption spectroscopy (AA 240 Varian Co.) in the laboratory of Health Faculty in Golestan University of Medical Sciences. Results: The average concentrations of Pb, Cd, Ni, and Cr in the effluent were 0.105 ± 0.06, 0.0089 ± 0.008, 0.095 ± 0.108, and 0.102 ± 0.175 mg/L, respectively. The concentrations of Pb, Cd, Ni, and Cr in returned sludge were 323.48 ± 217.65, 2.44 ± 3.3, 354.14 ± 322.79, and 388.53 ± 252.59 mg1/kg of dry weight, respectively. Also, in dried sludge, the average concentrations of lead, cadmium, nickel, and chromium were 58.48±2.67, N.D, 30.31±1.98, and 506.25±813.81 mg/kg of dry weight, respectively. Conclusion: The concentrations of heavy metals in wastewater effluent and dried sludge, except in returned sludge, were below the standards. Due to long-term use of effluents, necessity of treatment of other parameters, and the effect of bioaccumulation of metals in sludge, caution should be taken for their agricultural application. Also, because of importance of this type of contaminants in soil and food products, continuous monitoring by water companies is highly necessary. © 2017, Mazandaran University of Medical Sciences. All rights reserved

Heavy metal contamination in the effluent and sludges of wastewater treatment plant in Gorgan, Iran

Background and purpose: Environmental pollution by heavy metals and their transfer to soil and crops are a growing global problem. This study aimed to measure the concentrations of heavy metals in wastewater and sludge wastewater treatment plant in Gorgan, Iran. Materials and methods: In this cross-sectional study, 176 samples of effluent, and returned and dried sludges were analyzed in wastewater treatment plant in Gorgan, during six months in 2016. The concentration of Pb, Cd, Ni, and Cr were determined using polarography (Metrohm797 AV) and furnace atomic adsorption spectroscopy (AA 240 Varian Co.) in the laboratory of Health Faculty in Golestan University of Medical Sciences. Results: The average concentrations of Pb, Cd, Ni, and Cr in the effluent were 0.105 ± 0.06, 0.0089 ± 0.008, 0.095 ± 0.108, and 0.102 ± 0.175 mg/L, respectively. The concentrations of Pb, Cd, Ni, and Cr in returned sludge were 323.48 ± 217.65, 2.44 ± 3.3, 354.14 ± 322.79, and 388.53 ± 252.59 mg1/kg of dry weight, respectively. Also, in dried sludge, the average concentrations of lead, cadmium, nickel, and chromium were 58.48±2.67, N.D, 30.31±1.98, and 506.25±813.81 mg/kg of dry weight, respectively. Conclusion: The concentrations of heavy metals in wastewater effluent and dried sludge, except in returned sludge, were below the standards. Due to long-term use of effluents, necessity of treatment of other parameters, and the effect of bioaccumulation of metals in sludge, caution should be taken for their agricultural application. Also, because of importance of this type of contaminants in soil and food products, continuous monitoring by water companies is highly necessary. © 2017, Mazandaran University of Medical Sciences. All rights reserved