Performance evaluation of a bipolar electrolysis/electrocoagulation (EL/EC) reactor to enhance the sludge dewaterability

The present study aimed to evaluate the performance of a bipolar electrolysis/electrocoagulation reactor designed to enhance the sludge dewaterability. The reactor was 15 L in volume, with two series of plates used in it; Ti/RuO₂ plates for the electrolysis of the sludge, and also aluminum and iron plates for electrocoagulation process. The dewaterability of the sludge was determined in terms of its capillary suction time (CST) and specific resistance to filtration (SRF), while the degree of sludge disintegration was determined based on the value of degree of sludge disintegration (DD_SCOD). The maximum reduction in CST and SRF was observed at a detention time of 20 min and a voltage of 30 V. However, increasing of both detention time and voltage significantly increased the values of CST and SRF even to an extent that they both exceeded those of the untreated sludge. The optimal degree of sludge disintegration achieved by the present study was 2.5%, which was also achieved at a detention time of 20 min and a voltage of 30 V. As reported previously, increased DD_SCOD values led to increasing CST and SRF values, due primarily to the disruption of the sludge flocs. According to the results from the present study, it can be concluded that simultaneous application of electrocoagulation and electrolysis is effective in enhancing the sludge dewaterability, because electrocoagulation helps to achieve a higher degree of sludge disintegration while maintaining the desired sludge dewaterability.     

Spatial and temporal variability of fluoride concentrations in groundwater resources of Larestan and Gerash regions in Iran from 2003 to 2010

Environmental Geochemistry and Health - There is discrepancy about intervals of fluoride monitoring in groundwater resources by Iranian authorities. Spatial and temporal variability of fluoride in...     

Application of electrochemical reactor divided by cellulosic membrane for optimized simultaneous removal of phenols,chromium, and ammonia from tannery effluents

The post treatment of simulated tannery wastewater was evaluated in an electrochemical oxidation process under galvanostatic conditions. A continuous flow reactor divided by a cellulosic membrane consisted of Ti/SnO₂–Sb anodes and iron cathodes was used. Central composite design and response surface methodology (RSM) were applied to investigate the effects of six operational parameters, namely initial concentration of total phenols (TPh), total chromium (TCr), total ammonia nitrogen (TAN), flow rate (Q), current intensity (I), and electrode surface area (A). Effectiveness of the innovative cellulosic membrane was proven by considerable pH variations in the anolyte and catholyte chambers. A faster removal rate was observed for TPh and TAN, followed by TCr. The treatment level was very sensitive to Q and I in the studied ranges. RSM showed the removal efficiencies of 78.14%, 63.42%, and 86.09% for TPh, TCr, and TAN, respectively, are achieved under optimal conditions with consumption of only 9.03 kWh m^?3 electrical energy. Chlorinated compounds such as chloroform, 2,4-dichlorophenol, and chlorobenzene were detected as the degradation intermediates. According to the obtained results, electrolysis in the divided cell with cellulosic membrane is a practical, cost-effective method for advanced treatment of tannery effluents.     

Study of trace elements in wet atmospheric precipitation in Tehran,Iran

In this study, measurements of the trace metals Zn, Cd, Cr, Ni, Pb, Cu, Fe and Al were performed on 53 wet atmospheric precipitation samples (snow and rainwater) collected at a central site of Tehran. Samples were collected using a bulk sampler equipped with a high-density polyethylene funnel from November to May in 2011 and 2012 on the roof of a building in the city centre. Trace metals in the filtered samples were measured with ICP-MS. Statistical analysis of the results revealed that Al, which is principally a crustal-derived element, was the highest mean measured concentration. The pH ranged from 4.2 to 7.1 with a mean value of 5.1. Crustal enrichment factors (EF_c) related to the relative abundance of elements in crustal material was calculated using Al as reference crustal. EF_c calculations indicated that samples were not enriched with Fe and Cr but were, fairly to extremely, enriched with Zn, Cd, Ni, Pb and Cu. Factor component analysis with varimax-normalized rotation was conducted to find the probable sources of the measured species. This resulted in two factors with eigenvalues greater than unity. Factor 1 showed an anthropogenic source, mostly industrial combustion and local traffic emissions, for Zn, Cd, Ni, Pb, and Cu while factor 2 showed a crustal contribution for Al, Fe and Cr.     

A comprehensive systematic review of photocatalytic degradation of pesticides using nano TiO2

Environmental Science and Pollution Research - This study has systematically reviewed all of the research articles about the photocatalytic degradation of pesticides using titanium dioxide (TiO2)...     

Fish and shrimp waste management at household and market in Bushehr,Iran

Journal of Material Cycles and Waste Management - The aim of this study was to investigate the estimation and management of fish and shrimp wastes in Bushehr province. Two-part questionnaire...     

Effect of fertilizer application on soil heavy metal concentration

A large amount of chemicals is annually applied at the agricultural soils as fertilizers and pesticides. Such applications may result in the increase of heavy metals particularly Cd, Pb, and As. The objective of this study was to investigate the variability of chemical applications on Cd, Pb, and As concentrations of wheat-cultivated soils. Consequently, a study area was designed and was divided into four subareas (A, B, C, and D). The soil sampling was carried out in 40 points of cultivated durum wheat during the 2006–2007 periods. The samples were taken to the laboratory to measure their heavy metal concentration, soil texture, pH, electrical conductivity, cationic exchange capacity, organic matter, and carbonate contents. The result indicated that Cd, Pb, and As concentrations were increased in the cultivated soils due to fertilizer application. Although the statistical analysis indicates that these heavy metals increased significantly (P value < 0.05), the lead and arsenic concentrations were increased dramatically compared to Cd concentration. This can be related to overapplication of fertilizers as well as the pesticides that are used to replant plant pests, herbs, and rats.     

Determination of aluminum and zinc in Iranian consumed tea

To determine aluminum and zinc in Iranian consumed tea, 31 tea samples were analysed for Al and Zn concentration of tea leaves and tea infusion. The results show that average concentration of Al and Zn in tea leaves was 326 and 50.7 mg. Kg(-1) respectively in this regard Nemoneh and Shahrzad show the highest and lowest concentration respectively in term of Al, also Debsh and Alkozi follow same situation in Zn concentration. Also the solubility of metals in the first infusion was significantly (Al, Zn: P < 0.01) higher than the second infusion and the solubility in the second infusion was also significantly higher than the third infusion (Al: P < 0.01; Zn: P < 0.05). Al leachate in the first infusion (2 min) for Mosama and Seilan tea was highest and lowest respectively. Also in the second and third infusion (5 and 10 min) Golkis and Nemoneh tea show the highest and lowest figures respectively. On the other hand, data from Zn transfer in tea infusion in the first infusion show that Mosama and Ahmad Atry tea have the highest and lowest leachate percentage respectively, while in the second and third infusion Mosama and Golkis tea follow the same situation. Calculation of percentage 'available' Al and Zn to the human system showed that 1 l of tea can provide 37.2% of the daily dietary intake of Al, the percentage 'available' for absorption in the intestine is only 1.78% for overall mean Al concentration. Also daily dietary intake of Zn was 2.13% while percentage available for absorption in the intestine was 0.72%.     

Photocatalytic removal of diazinon from aqueous solutions: a quantitative systematic review

Environmental Science and Pollution Research - Diazinon is a widely used pesticide that can be effectively degraded in aqueous solutions via photocatalytic oxidation. This quantitative systematic...