A full-cyclic automatic control strategy for sequencing batch reactors (SBR) was proposed using only common sensors such as ORP, DO and pH. The main objective was to develop a generally applicable and robust control strategy. To accomplish this, various control schemes found in the literature or suggested by authors were examined at diverse ammonia loads and SCOD/NH4+-N ratios. Advantages and constraints of each scheme were discussed and compared. Ammonia load was estimated with DO lag time during the aerobic stage, and then the influent pump was manipulated to meet the desired load at the next anoxic stage. A partial denitrification scheme was chosen for the anoxic stage period control, to save anoxic time and external carbon. For external carbon dosage control, intermittent feeding at each anoxic stage was concluded to be a suitable scheme. The anoxic stage period could be successfully controlled by the combination of pH increase and DO increase. Every suggested control scheme was incorporated into a full-cyclic control strategy and tested at 0.02, 0.035, 0.08 kg NH4+-N/m3/sub-cycle. From the results, it is expected to perform unmanned automatic SBR operation with this strategy.
Bioelectrochemical systems (BES) use electrochemically active biofilm on the electrode as biocatalyst for electrical energy recovery and useful products. BES has been extensively investigated for application to recover bioenergy in the from of electricity and biohydrogen from biodegradable organic matter, biosensor, bioremediation and microbial desalination. The biofilm of BES can exchange electron with the electrode which makes different biological application and metabolic capability of attached microorganisms from the conventional biofilm process. The microbial oxidation and reduction can be combined with ion exchange capability by membrane and separator in the processes, therefore it might be able to facilitate production and separation in the same process. Recently, BES has also been designed to Microbial electrosynthesis (MES) which can reduce proton in cathode chamber into hydrogen and higher organic compounds such as volatile fatty acids and alcohol with power boost-up using external power supply. It was reported that the dual energy source in MEC using both electrical energy from bio- oxidation of organics and power supply can increase energy and coulombic efficiency to 80% and 92%, respectively. Furthermore, the BES concept recently has been introduced into biorefinery which synthesize chemicals by using microbial electron transport between electrode and live bacterial cell. In this process, the cathodic reduction is more focused than the anodic oxidation of organic matters. Alkaline and commodity chemicals such as methane, acetate, ethanol and buthanol can be produced by biotic cathodic reduction reaction using controlled poised potential. This report will investigate the recent findings of BES and its future application for useful product and biorefinery.
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