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The aim of this research is to achieve an efficient and cheap methods to remove H2S from the factories emissions. Four serial cylinders are designed, 40 cm in height and 15 cm in diameter each. They are filled with bivalve seashells with 63% porosity which contains Thiobacillus thioparus bacteria to the maximum height of 27.5 cm. By mixing phosphoric acid and sodium sulfide, H2S gas is released and its concentration is measured as mg m(-3) before injecting into the cylinders. A permanent measuring instrument is equipped to control the gas coming out of the cylinders. In order to prevent the outdoor environment from pollution, first the gas is sent through two activated carbon columns and then sent through a ferrous chloride scrubber. Finally it is burnt directly by flames. There were 550 sample readings in 15 weeks. The changes in the discharge of the air which carries the gas are considered between 1-12 L min(-1) and the concentration of the influent pollutant is considered between 1-140 mg m(-3). Also the humidity in the atmosphere is fixed between 77-93% and the optimum temperature required for growing of the microorganisms is retained between 20.5-30 degrees C. After feeding the system for three weeks the efficiency started to increase so that by the end of the final week of this research the efficiency reached to 90% with the discharge of 6 L min(-1) of the carrier gas. The results achieved from this research show that because of not using Filamentous bacteria, clogging did not occur in the biological system in biofilters. The amount of head loss in cylinder was only 2 mm water and during this research, head loss was the same due to unclogging of filter. On the other hand the traditional methods are expensive in terms of using chemicals, carbon recycling and using fuel and etc. Therefore researchers have started new studies in this field. The above mentioned method, according to high efficiency, inexpensiveness and easiness of control and maintenance is considered one of the best methods.

The quality of water resources used for drinking and their health effects is vitally important. The present study investigated the concentrations of F¯, NO3¯, and metal elements like Hg, Mn, As, and Pb in the groundwater resources and their health risk assessment. The study area was part of West Azerbaijan, west of Urmia Lake, located northwest of Iran. Sampling points were selected and were taken from 121 groundwater resources. Heavy metals (Pb, As, Mn, and Hg) and ions (Na+, NO3¯, F¯, and Cl¯) were measured, respectively. The probabilistic method and Monte-Carlo simulation are used to estimate carcinogenic and Noncarcinogenic risks. The Concentration of study elements was obtained in the range of the World Health Organization (WHO) recommended. The order of Heavy metals (HMs) concentrations is based on the overall mean: Mn > As > Hg > Pb. The hazard index (HI) level was found to be more than 1 for noncarcinogenic risk for As and NO3¯, also permissible risks for the other elements. ELCR levels of As were acceptable, except for some sampling points, the central region in the study area, near the seashore of Urmia Lake. Finally, it can be stated that the groundwater resources in the studied area are acceptable for drinking in most places. Still, due to the effects of As and NO3¯ contaminated water, the quality is unacceptable for drinking in some places. So, in the study area, monitoring water quality is recommended by finding contamination sources to decrease the health risks of drinking consumption.