Bench scale study of moving bed biofilm reactor application as pre-treatment of raw water for water treatment plant (Case study: Pesanggrahan River)

Abstract

The quality of surface water in Jakarta is on a serious polluted status. In order to reduce the Water Treatment processing load, a pre-treatment process is needed to eliminate parameters such as organic matter, ammonia, color, taste, and odor. This treatment generally uses chemical and physical processes, such as chlorination and activated carbon that produce harmful byproducts. Moving Bed Biofilm Reactor (MBBR) is one of the solutions developed to reduce the nutrient and organic levels in raw water. This study aims to improve the quality of raw water, by reducing the concentration of COD, NH3-N, Phosphate, and TSS before entering the conventional process. Reactor performance is assessed based on contaminant removal efficiency with variation of residence time (1 hour, 1.5 hours, 2 hours). The reactor is operated by using Kaldness K1 as the medium and oxygen supply of 7 L/min. The optimum residence time is 1,5 hours with the ability to remove COD, NH3-N, Phosphate, TSS 51.8% ± 0.2; 54.3% ± 0.28; 52.6% ± 0.19; and 77.7% ± 0.14 respectively. Based on the optimum residence time, the kinetics of the ammonia removal rate in MBBR takes place at zero order, with a rate constant removal of 0.0056 g/m2.day. The results showed that the higher concentration of ammonia, and organic contaminants treated, the higher the efficiency of MBBR. Apart from water quality improvement, pre-treatment process using MBBR can reduce coagulant dose from 50 mg/L to 9 mg/L, to decrease raw water turbidity from 135 NTU to 0.68 NTU before entering the coagulation-flocculation unit.