Articles

Efficiency of Rhodopseudomonas faecalis in Increasing Digestion of Substrate in an Anaerobic Digester

/in /by

An anaerobic Purple Non Sulphur Bacteria (PNSB), Rhodopseudomonas faecalis was utilized as an inoculum to study the efficiency of a biogas digester. A 5 litre capacity anaerobic digester was prepared with 10% feed, 30 days of Hydraulic Retention Time (HRT) was studied using canteen waste as a substrate.  Parameters like pH, Temperature, Chemical Oxygen Demand (COD), Total Solids (TS), Volatile Solids (VS) and gas production were analyzed and recorded on every day. It was found that pH was decreased and temperature was varying. Increase in the digestion of the substrates was due to the addition of the bacterium eventually causing decrease in COD, TS & VS, was observed. This has increased the production of biogas in the digester.

Kinetic Study on the Effect of Substrate and Micronutrient Inhibition during Anaerobic Fermentation of Biohydrogen

/in /by

There are several factors that influence the production of biohydrogen by dark fermentation including inoculum seeds, type and concentration of substrate, pH, temperature, presence of micronutrient and reactor configuration. Previous research has proven that the concentration of substrate and the presence of micronutrient will influence the yield and productivity of biohydrogen production. However, improvement of yield and productivity of the process can only be achieved once the system is under the optimum amount of substrate and micronutrient. Therefore, the best way to determine the effect of substrate concentration and presence of micronutrient is through kinetic study that was done using Monod model along with Andrews model. Besides that, the substrate inhibition effect also will be evaluated to determine the maximum substrate that needs to be supplied for maximum hydrogen production, and thus supplied the information for economic feasibility for fermentation process. In the meantime, the inhibition effect of adding the iron nanoparticles also had been evaluated in order to understand the interaction effect between iron nanoparticles and bacteria in term of catabolism reaction. It was found that increasing the substrate concentration more than 10 g/l will cause the inhibition to the system, in which it will slow down the reaction process and reduced the production of hydrogen. While the presence of iron NPs more than its optimum value (200 mg/l) will inhibit the bacterial growth and hence, affect the hydrogen production. For both cases, when the inhibition occurred at the respective concentration, it was found that the metabolic pathway was shifted to produce more hydrogen-consuming metabolite such as propionate acid, and thus, dropped the hydrogen production.