The wasted activated sludge (WAS) was sintered with laterite and iron oxide to form porous pellets which were added into a sequencing batch biofilm reactor (SBBR) in two different filling ratios (20 and 40%) as a cell immobilizing carrier for nitrogen removal. Hydroxylamine (NH2OH) production was used for identifying and modelling the simultaneous nitrification and denitrification (SND) process in SBBR. The results showed that the more NH2OH was released, the more ammonium was converted into nitrite, and the SND nitrogen removal efficiency (ESND) also increased due to higher nitrification rate constant in the system. In the first part of the SND process, the specific NH2OH and NO2- release rates of 9.5 × 10-7 mg NH2OH g-1 MLSS min-1 and 6.1 × 10-5 mg NO2- g-1 MLSS min-1 were measured. When the COD/N ratio was 8.1, the removal efficiencies of COD and ammonium were 95 and 98%, respectively. The hydroxylamine and nitrite production rates during the nitrification reaction were 5.8 × 10-7 mg NH2OH g-1 MLSS min-1 and 9.5 × 10-7 mg NO2- g-1 MLSS min-1, respectively. Furthermore, the SND reaction rate coefficient (kSND) for the SBBR-40% filling ratio system (kSND = 8.6) was better than that of the 20% SBBR filling system (kSND = 8.3). The ESND of the SBBR with pellet filling ratio of 20 and 40% were 94 and 98%. The overall results suggest that the higher the carrier filling ratio, the more biomass could be retained in the reactors, and this could increase biomass concentration in reactors with corresponding higher specific removal efficiencies.
Raw coal of Khoot deposit and pyrolyzed coal samples were analyzed for ash content and composition, surface area and porosity, as well as thermal conversion characteristics in air atmospheres. The results confirm that the Khoot coal is a middle-rank sub-bituminous B-D mark coal. The porosity of raw coal, char of pyrolyzed coal or after thermolysis (thermal dissolution) was determined by scanning electron microscopes. The liquid tar product of thermolysis of Khoot coal was investigated by Fourier transform infrared spectroscopy, 13C and 1H nuclear magnetic resonance spectrometric analysis. The results of thermal dissolution of Khoot coal in tetralin with constant mass ratio between coal and tetralin (1:1.8) at 450°C show that 61% of liquid product can be obtained after thermal decomposition of the coal organic mass. The char after pyrolysis was activated by heated water steam (called char made activated carbon). The inherent physiochemical characteristics of sub-bituminous coal largely influence the development of micro-and meso-structure within the activated carbon. Activated carbon from sub-bituminous coal was the most effective in removing Methylene Blue from an aqueous solution.