Modeling Bacterial Decay Coefficient during SSDML Process

Abstract

The simultaneous sludge digestion and metal leaching (SSDML) process can leach out heavy metals, achieve sludge solids reduction, and eliminate sludge pathogens. The potential for application in the wastewater treatment industry requires a sound knowledge of the system kinetics. The present work targets a better understanding of the qualitative as well as quantitative relationships between solids reduction rate and other parameters such as sludge pH, initial MLSS concentration, and availability of oxygen during the SSDML process. Experiments were carried out in laboratory batch reactors (20 L working volume) as well as in a 4,000 L capacity pilot facility. Based on the results of these experiments, it was concluded that degradation rate of sludge volatile matter is influenced by (1) sludge pH; (2) availability of oxygen; and (3) initial mixed liquor suspended solids (MLSS) concentration of the sludge. The degradation rate constant for biodegradable fraction of the mixed liquor volatile suspended solids [MLVSS(B)] was computed for various initial MLVSS concentration and sludge pH ranges. The value of