Iranian Journal of

Background and Objectives: In this experimental study, we used Analytical Hierarchy Process method to determine the best wastewater treatment process for dairy products factories. That is a multi-criteria decision making techniques and is based on expert knowledge. Materials and Methods: First, we formed the hierarchical structure and defined the main criteria and indicators. Then, we investigated the current situation of the treatment process through field observations and conducting influent-effluent analysis. Later, we converted the results obtained into quantitative indices. Then we weighted the main criteria, and their related sub criteria, depending on existing conditions we performed the experiments required and considered the experts ideas. Finally, Evaluation and prioritization of the options was conducted using Expert choice software. Then the sensitivity analysis was performed for main criteria and we evaluated the influence of the parameters weight change on the options. Results: In comparison with the main criteria, environmental criteria were more important followed by engineering criteria, economic and management criteria. Conclusions: Due to the influence of various parameters in choosing optimal wastewater treatment, Multi-criteria decision-making methods are necessary. Finally, “UASB + Aeration” was found to be the first priority followed by “Anaerobic filter + Aeration”, “Anaerobic lagoon + Aeration (2) + Sedimentation (2)”,” Anaerobic filter + Aeration (2) + Sedimentation (2)”. “Septic tank + Trickling filter + Aeration” system was found to be less preferable than other options.

Background and Objective: Petroleum hydrocarbons are a bunch of pollutants hazardous to the environment. Nowadays, biodegradation of petroleum contaminants is considered as one of the most efficient and most cost effective methods of removing oil contamination from the environment. The main objective of this study is to investigate the potential of cyanobacterium Schizothrix vaginata ISC108 in the biodegradation of crude oil and to evaluate oil effects on growth rates, dry weight, and chlorophyll content. Material and Methods: In this experimental study, the cyanobacterium Schizothrix vaginata ISC108 was obtained from the algal culture collection of Research Institute of Applied Science, ACECR, Tehran, Iran. First, purification of the cyanobacterium was performed using agar plate method on solid medium of BG11. Growth rate, chlorophyll content and dry weight of cyanobacteriaum was measured using spectrophotometry method. The biodegradation rate of crude oil was calculated using gas chromatography (GC) analysis. Results: Measuring the growth rate of cyanobacterium Schizothrix vaginata at 1% treatment of crude oil and control samples showed that the growth of cyanobacterium in the presence of crude oil as the sole carbon source increases at the same rate as the control sample. Moreover, it was found that increasing the concentration of crude oil will result in increasing dry weight of Schizothrix vaginata however, and the chlorophyll content reduced in various crude oil treatments. The average biodegradation of petroleum hydrocarbon after 14 and 28 days of treatment was 54.78 and 93.98% respectively. Conclusions: It was found that cyanobacterium Schizothrix vaginata ISC108 has great potential in biodegradation of crude oil. Therefore, since oil is a product toxic to biological systems and is one of the main pollutants of bioecosystem, it has a great potential to be used as an indicator to eliminate pollution in contaminated areas.