INTEGRATED SOLAR AND HYDRAULIC JUMP ENHANCED WASTE STABILIZATION POND

ABSTRACT

This study on the integrated solar and hydraulic jump enhanced waste stabilization pond (ISHJEWSP) is aimed at determining the effect of variations in solar radiation, hydraulic jump, hydro-kinematic factors and pond geometry, on the treatment efficiency of wastewater in the ISHJEWSP. An equation to account for these effects was derived, calibrated and verified. An empirical regression model for the prediction of the Biochemical Oxygen Demand (BOD5) in the ISHJEWSP for sewage treatment was also developed. Three sets of experimental ponds with varying locations of slopes were constructed using metallic tanks with each set consisting of eight numbers of ponds with varying width. Also, solar reflectors were constructed to increase the incident sunlight intensity. Wastewater samples collected from the inlet and outlet for varying inlet velocities of the ISHJEWSPs were examined for physicochemical and biological characteristics for a period of nine months. The parameters examined were temperature, pH, detention time, dissolved oxygen, total coliform count, total suspended solids, E-coli, algae concentration, BOD5 and tracers studies. The efficiencies of the ISHJEWSPs with respect to these parameters fluctuated with variations in solar radiation, width, inlet velocity and location of point of initiation of hydraulic jump with the smallest ISHJEWSP in width giving the highest treatment efficiency at higher intensities of solar radiation. It was generally observed that the treatment efficiencies of the ISHJEWSPs increased as the location of the point of initiation of the hydraulic jump decreased relative to the inlet and with increase in inlet velocity for all sets studied though with precedence to solar radiation and temperature. A comparison of the conventional WSP and the ISHJEWSP showed that the bacteria removal was significantly higher in the ISHJEWSP than the conventional pond at a significance level of 5%. The verification of the conventional model gave a good average coefficient of correlation of R = 0.800 (0.713 to 0.891) between the measured and calculated Ne/No with an average standard error of 0.173 (0.157 to 0.224) and average R = 0.924(0.858 to 0.965) and average standard error of 0.034 (0.010 to 0.060) for the ISHJEWSP, respectively. An empirical model was developed to predict the BOD5 in the ISHJEWSP based on the independent variables of pH, temperature, algae concentration, dissolved oxygen, inlet velocity, location of point of initiation of hydraulic jump, angle of inclination causing hydraulic jump and intensity of solar radiationr. The empirical regression model developed gave a good multiple regression coefficient of correlation of 0.938 with a standard error of 5.224 at a significance level of 10%.