Some natural organic compounds (NOC) such as aromatic compounds can trigger the formation of disinfection by-products (DBPs). In chlorination (disinfectant) process resultant water quality depletes. Some safe alternative oxidants are needed for cleaning water pollutants. KMnO4 had shown better oxidation results, especially for reducing aromatic and non-aromatic organic compounds present in water. The aim of this study was to analyze the effect of KMnO4 and Ca(OCl)2 oxidants on the concentration of high and low molecular weight organic matter including aromatic compounds in the water sample. In this experiment, artificial organic compounds, namely sinapic acid (high molecular weight aromatic compound) and resorcinol (low molecular weight aromatic compound) were used to identify the characteristic of organic matter under different molecular weights. Sinapic acid and resorcinol were oxidized by using KMnO4 and Ca(OCl)2 with a minimum contact time of 60 minutes. Samples were analyzed for aromatic contents and total organic carbon (TOC) before and after completion of the experiment by using UV-Vis spectrophotometer at 254 nm wavelength (UV254). It has been observed that both oxidants increased TOC concentration. Ca(OCl)2 produces a higher percentage of organic matter degradation by-products (DBPs) such as chloroform (CHCl3) a highly toxic compound than KMnO4. Since Ca(OCl)2 has a higher oxidation potential than KMnO4. It has been observed that KMnO4 is a safer oxidant than Ca(OCl)2 as potassium permanganate produces less amount of DBPs.

This paper is aimed to investigate the oxidation ability of the bacteria (Thiobacillus thioparus, Z-2) and the biological oxidation mechanism and oxidation kinetics on the reduced inorganic sulphuric compounds in sodium-process desulphurization wastewater. Results showed that the Z-2 bacteria have high oxidation activity in the high-salt environment after acclimation, and the oxidation percentage of reduced inorganic sulphuric compounds reached 95% and the chemical oxygen demand (COD) reduced from 18000mg/L to 2000 mg/L in the high-salt environment. This showed that the Z-2 bacteria have strong salt resistance and high oxidation activity. In addition, ion chromatography analysis confirmed that Z-2 bacteria were beneficial for the oxidation of reduced sulphur. A biological oxidation model was constructed by measuring the enzyme activity of the oxidation process. The results indicated that direct and indirect oxidation processes were both involved in biological oxidation. The kinetic parameters of Vmax (21.38 µM/min) and Km (79.04 µM) were obtained through biological oxidation kinetic experiments.