Tanning Wastewater Pre-Treatment Using Electrocoagulation Process

Background: The leather industry is one of the most polluting industries in the country (Iran), which annually produces several hundred tons of industrial sewage. Electrocoagulation is one of the purification methods for this wastewater. This research aimed to remove COD and turbidity from real wastewater originating from one of the leather tanning units in Charmshahr industrial park with use of electrocoagulation process. Method: The research was conducted in laboratory scale in a 480-millimeter EC reactor. The wastewater was collected from a leather tanning unit. The main variables considered were current intensity (1.5, 2.5, 3.5 and 5 A), retention time (5, 10, 15 and 30min), initial pH (5, 6 and 8.6) and electrode material (i.e., iron, aluminum, and steel). Results: The optimum conditions in the electrocoagulation process to achieve the maximum removal efficiency for COD equal to 63.57% were obtained in an experiment with time of 5 minutes, the current density of 23.5% mA/cm2, pH=8.62 and 2 steel electrodes. Also, in an experiment with time of 30 minutes, the current density of 23.5 mA/cm2, pH=8.62 and 4 electrodes, the removal rate of 62.88% was obtained. Conclusions: The results of the present study showed that the electrocoagulation can be an effective method for tannery wastewater pre-treatment and the optimum conditions can be obtained using aluminum electrodes, time of 5 minutes, the current density of 7 mA/cm2 and pH of 8.62. &nbsp

Removal of High Concentrations of Sulfate from Wastewater: Evaluating Different Methods and Proposing the Best Option

Background: Industrial wastewaters containing high amounts of compounds such as sulfate can cause serious risks to human health and environment. Therefore, proposing practical solutions with the lowest cost and the highest efficiency for pollutants removal is of special importance. The purpose of this study is to find a suitable method for treatment wastewater containing very high amounts of sulfate. Materials and Methods: This research is an experimental-research study in which four different practical methods have been investigated for treatment of sulfate containing wastewater including chemical precipitation with lime, electrocoagulation, biological degradation and thermal distillation. Results: After examining the performance of different methods and considering the special characteristics of wastewater, the results showed that the methods of chemical precipitation (removal efficiency of 5%) and electrocoagulation (removal efficiency of 7%) were less efficient. The distillation process also showed an acceptable performance in removing TDS and sulfate from this wastewater (removal efficiency of 98.7%) and the biological method could function well after wastewater dilution (the removal percentage of sulfate in the first 24 hours for wastewater with dilutions of 10, 25 and 50%, are about 55, 40 and 17%, respectively). Conclusions: According to the results obtained from this study, methods of chemical precipitation and electrocoagulation are proposed only as a pre-treatment method and biological treatment can be used as a supplementary treatment after pre-treatment. Distillation is also not recommended as a practical method due to high cost and energy consumption

Investigation of Coagulation and Flocculation Process in Chemical Pre-Treatment of Livestock Wastewater

Background: Development of communities, population growth, and enhancement of the health indicators has led to a significant increase in dairy and meat consumption, and consequential growth in the livestock industry. As the result, the environmental problems which cause by such industrial wastewater has increased. Livestock wastewater considered as a very non-biodegradable and polluted wastewater. In this study, the performance of livestock wastewater pre-treatment, by using coagulation and flocculation method, in order to reduce the pollutants concentration and improve wastewater properties were investigated. Methods: In the experimental methods, the Jar test unit was used as a batch reactor; FeCl3, PAC, and Alum as coagulants; and two polyelectrolytes: Zetafloc and Megafloc as cationic and anionic flocculants. The effects of coagulant dosage and type, flocculant type, and pH on the removal of COD and turbidity from wastewater were investigated in three stages. The wastewater with initial COD and turbidity of 12250 mg/L and 7125 NTU, respectively, was collected from a livestock unit. Results: The optimum conditions in the coagulation and flocculation process to achieve the maximum removal efficiency for COD (29.6%) and turbidity (52.8%) were obtained in an experiment with FeCl3 at a concentration of 400 mg/L, pH=8, and using an anionic flocculant. Conclusion: The results of the present study showed that the coagulation and flocculation process can be an effective method for livestock wastewater pre-treatment

Micrometastasis in non-small-cell lung cancer: Detection and staging

Background: The clinical relevance of bone marrow micrometastasis (BMM) in non-small-cell lung cancer is undetermined, and the value of such analyses in advanced stage patients has not been clearly assessed previously. This study was conducted to estimate the accuracy of both polymerase chain reaction (PCR) and immunohistochemistry (IHC) in micrometastases detection and determine the best site for bone marrow biopsy in order to find micrometastasis. Methods: This prospective cross-sectional study was performed in the Department of Thoracic Surgery, Alzahra University Hospital from September 2008 to June 2009. To evaluate the bone marrow, a 3-cm rib segment and an aspirated specimen from the iliac bone prior to tumor resection were taken. PCR and IHC were performed for each specimen to find micrometastasis. Results: Of 41 patients, 14 (34%) were positive for BMM by PCR compared with two positive IHC (4.8%). All BMMs were diagnosed in rib segments, and iliac specimens were all free from metastatic lesion. Our data showed no significant association between variables such as age, sex, histology, tumor location, side of tumor, involved lobe, smoking, or weight loss and presence of BMM. Conclusion: PCR could use as a promising method for BMM detection. BMM in a sanctuary site (rib) is not associated with advanced stages of lung cancer. In addition, when predictor variables such as age, sex, histology, tumor location, smoking, or weight loss are analyzed, no correlation can be found between micrometastasis prevalence and any of those variables