Development of biochemical sulfide potential (BSP) test for sulfidogenic biotechnology application

The determination of organics biodegradability and corresponding biodegradation kinetics provides valuable information on the optimal design and operation of anaerobic biotechnology especially for sulfidogenesis. This study proposes a deterministic method, i.e. a biochemical sulfide potential (BSP) test, and compares it to the conventional biochemical methane potential (BMP) test in terms of their ability to characterize sulfate-laden organic waste biodegradability. It demonstrated 1.48 times higher degradation of volatile suspended solids (VSS) and 2.60 times more chemical oxygen demand (COD) conversion in its major metabolites than the BMP test. Moreover, it required only four days to complete, compared to the 35 days required by the BMP test. Through the two-substrate first-order hydrolysis model, it was revealed that the shortened time was attributed to the enhanced degradation rates from both readily (eight times) and slowly (nearly 10 times) biodegradable organic substrates in the BSP test compared with the BMP test for the same sulfate-laden organic waste. The findings highlight the inappropriateness of the BMP test to sulfidogenic applications due to the underestimated predictions of organic waste biodegradability and excessive time requirements. Furthermore, the ability of the BSP test to identify the average elemental composition (C_xH_yO_zN_aP_bS_c) of substrate biodegradable particulate organics (BPO) is explored and verified using a casein-based validation test. Using BPO elemental composition as the input variable, a BSP biochemical kinetic model is thereby developed to predict BSR performance and possible dynamic process control. Overall, this study demonstrates the applicability and advantages of the BSP test in sulfidogenic applications for characterization of organics biodegradability and identification of BPO average elemental composition, furthermore develops a process model utilizing the derived BPO average elemental composition to provide optimized reactor retention time and substrates feed mixture for optimum performance.