Natural coagulants have been the focus of research of many investigators through the last decade owing to the problems caused by the chemical coagulants. Optimization of process parameters is vital for the effectiveness of coagulation process. In the present study optimization of parameters like pH, dose of coagulant and mixing speed were studied using natural coagulants sago and chitin in comparison with alum. Jar test apparatus was used to perform the coagulation. The results showed that the removal of turbidity was up to 99 % by both alum and chitin at lower doses of coagulant, i.e., 0.1-0.3 g/L, whereas sago has shown a reduction of 70-100 % at doses of 0.1 and 0.2 g/L. The optimum conditions observed for sago were 6 and 7 whereas chitin was stable at all pH ranges, lower coagulant doses, i.e., 0.1-0.3 g/L and mixing speed-rapid mixing at 100 rpm for 10 min and slow mixing 20 rpm for 20 min. Hence, it can be concluded that sago and chitin can be used for treating water even with large seasonal variation in turbidity.

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Quality of water, along Mandal headquarters of a coastal district of Andhra Pradesh, India, was assessed prior to and past rainfall season to determine water's acceptability for consumption using water quality index (WQI). The present work involved collecting groundwater samples from Mandal headquarters' locations present in the entire district. All the samples were analysed in a comprehensive way for ten physicochemical parameters, including pH, magnesium, calcium, chloride, sulphate, nitrates, total dissolved solids, fluoride, potassium, and sodium. The geographical information system was used for mapping sampling sites. The coordinates of sample collection areas were recorded employing GPS. Correlation matrices for cation–anion were illustrated and from the qualitative results of the samples. Results indicate that WQI prior and past-rainfall seasons ranged from 37.53 to 312.46; 42.04 to 211.89 in 2016, while for 2017, these were in the range of 25.01 to 137.06; 30.06 to 228.83. The present study's WQI values indicate that the water samples possess poor quality, and no fluoride contaminations were observed. The analysis suggests appropriate treatment of sub-surface water from the study site before consumption.

Installation layout of wind turbines plays a prominent role in the design of every wind farm. Thus, the wind farm layout optimization problem is proposed to maximize the total power output with the minimum cost. In this research, Kahrizak region in Tehran province of Iran is selected as a windy region and its real wind speed data are gleaned. Three different scenarios are also considered, with various number of generations and populations for GA parameters, effective distances, and longitude and latitude distances of turbines from each other. Among these scenarios, the best result is obtained for the one in which the longitudinal distance between turbines is greater than the latitudinal distance. By observing the wind rose of Kahrizak region, it is observed that the dominant wind direction of the region is toward the east and south-east. Therefore, by increasing the longitudinal distance of the turbines from each other, the efficiency can be improved and the turbine layout becomes more realistic. In this case, the efficiency rate and normalized cost of turbines are 89.5% and 37.4, respectively, and also 56 turbines are needed. The amounts of efficiency and power output are very convenient for real wind speed data of a region.