| This research is conducted in two parts: Part I deals with simulation of the microsand ballasted flocculation process, and Part II deals with development of a surrogate test to measure the 5-day BOD in raw and microsand ballast treated wastewater samples. The microsand ballasted flocculation process simulation was carried out using wastewater samples from the Village Creek wastewater treatment plant, Fort Worth, Texas. The quality of untreated and treated wastewater samples are evaluated by measuring BOD5 and key parameters of four selected surrogate tests. The microsand ballasted flocculation process consistently achieved excellent BOD removal. The principal BOD5 removal was due to adsorption onto ferric hydroxide floc. The peak average total BOD 5 removal was 67 percent at an Fe dose of 13.7 mg/L. PAC was also tried in conjunction with the microsand ballasted process to enhance the BOD removal, but the increase in BOD removal was insignificant. The four surrogate tests used in this study were: (1) specific oxygen uptake rate (SOUR), (2) 2-hour chemical oxygen demand (COD), (3) 15-minute chemical oxygen demand (COD), and (4) alkaline potassium permanganate test. Through these tests, a relationship was established between the 5-day BOD and the key parameter of each surrogate test. The relationship developed between the 5-day BOD and 15-minute COD test was good and reliable for both treated and untreated samples. The relationship developed in this study between BOD5 and the 15-minute COD test is recommended for use, as a surrogate test for the field trials. |
