Utilisation of raw palm oil mill effluent (POME) as a renewable substrate for fermentative H2 production: optimisation using statistical approach

ermentative H2 production was studied using raw POME as the substrate with heat-shock pre-treated POME anaerobic sludge acted as the inoculum. The effect of crucial operating variables (initial pH of medium, incubation temperature, and inoculum size) on H2 production was studied using Box−Behnken Design. A second-order polynomial regression model was generated to evaluate H2 production trend under conditions tested. The model analysis revealed the high significance of linear effects of initial pH, incubation temperature, and inoculum size (P < 0.01) towards H2 production. Similar results indicated that the interaction effect between initial pH and inoculum size, and interaction effect between incubation temperature and inoculum size were highly significant (P < 0.01). The regression model suggested that the optimum conditions were set to a pH value, incubation temperature and inoculum size of 6.4, 58.0°C and 8.0% v/v, respectively. In order to validate the optimum conditions determined by the model, heat-shock pre-treated POME anaerobic sludge was incubated with raw POME under optimum conditions. Validation experiment showed that a cumulative H2 volume of 239.0 mL was produced. Microbial community analysis of inoculum showed that mixed consortia between Clostridium sp. and other obligate anaerobic non-spore forming bacteria, mostly belonging to the Firmicutes and Bacteroidetes phyla were identified as the major H2-producers and were hugely responsible towards fermentative H2 production

Bioelectricity generation in microbial fuel cell using natural microflora and isolated pure culture bacteria from anaerobic palm oil mill effluent sludge

A double-chambered membrane microbial fuel cell (MFC) was constructed to investigate the potential use of natural microflora anaerobic palm oil mill effluent (POME) sludge and pure culture bacteria isolated from anaerobic POME sludge as inoculum for electricity generation. Sterilized final discharge POME was used as the substrate with no addition of nutrients. MFC operation using natural microflora anaerobic POME sludge showed a maximum power density and current density of 85.11 mW/m2 and 91.12 mA/m2 respectively. Bacterial identification using 16S rRNA analysis of the pure culture isolated from the biofilm on the anode MFC was identified as Pseudomonas aeruginosa strain ZH1. The electricity generated in MFC using P. aeruginosa strain ZH1 showed maximum power density and current density of 451.26 mW/m2 and 654.90 mA/m2 respectively which were five times higher in power density and seven times higher in current density compared to that of MFC using anaerobic POME sludge

Development and performance of BAC-ZS bacterial consortium as biofilm onto macrocomposites for raw textile wastewater treatment

One of the most abundant dyes that are used extensively in the textile manufacturing are azo dyes, which may endanger water bodies since incomplete breakdown of dyes may cause mutagenic and carcinogenic compounds to persist. In this study, BAC-ZS, bacterial mixed culture consisting of three acclimatised decolourising bacteria were grown as biofilm onto macrocomposites. Different time duration between 3 to 14 days of biofilm development was studied to determine the density of biofilm attached onto macrocomposites. Sequencing batch reactors (SBRs) were set up for raw textile wastewater treatment to investigate the effectiveness of the treatment with and without the presence of biofilm (control). The treatment was performed under facultative anaerobic-aerobic condition for 20 days continuously with 48-hour of hydraulic retention time (HRT) cycle (consisting both conditions). Colour and chemical oxygen demand (COD) were monitored throughout the treatment process. Results showed that the colour and COD removal by the developed biofilm were 78.6 ± 1.4% and 76.4 ± 1.12% from initial values of 1400 ADMI and 660 mg/L, respectively while only 47.9 ± 0.9% colour and 38.0 ± 1.5% COD removal for the control. In conclusion, the biofilm of BAC-ZS mixed culture coated onto macrocomposites showed potential applications in the treatment of raw textile wastewater