Tugba Keskin

Comparative Evaluation of Bio-Hydrogen Production From Cheese Whey Wastewater Under Thermophilic and Mesophilic Anaerobic Conditions

Hydrogen production from cheese whey wastewater via dark fermentation was conducted using mixed culture under mesophilic (36°C ± 1) and thermophilic (55°C ± 1) conditions, respectively. The hydrogen yields and specific hydrogen production rates were found as follows: mesophilic: 9.2 mmol H2 /g COD (chemical oxygen demand) and 5.1 mL H2 /g VSS h; thermophilic: 8.1 mmol H2 / g COD and 1.1 mL H2 /g VSS h. The reaction mixture for the mesophilic condition was composed of acetate (0.3–14.7%) and iso-butyrate (85–98%), plus other volatile fatty acids. On the other hand, the reactor mixture for the thermophilic condition was composed of acetate (1–43%) and iso-butyrate (29–46%).

Improvement in Anaerobic Degradation of Olive Mill Effluent (OME) by Pre-Treatment Using H2O2, UV-H2O2 and Fenton's Process

The pre-treatment using single H2O2, UV-H2O2 and Fentons process as a pre-treatment option for olive mill effluent (OME), which is known to contain a significant amount of inhibitory compounds (e.g., phenolics and tannins) was carried out in order to enhance anaerobic degradation of OME. Biochemical Methane Potential (BMP) assay was employed in order to monitor and comparatively evaluate any increase in biogas production as an indicator of improvement in anaerobic biological degradation before and after pre-treatment. The results suggested that pre-treatment using Fentons process resulted in an almost 3.5-fold enhancement in the biodegradability of OME, which was much lower if it was digested alone (without pre-treatment). Pre-treatment in the form of UV-H2O2 also significantly increased the biogas production (1.75-fold higher gas production than raw OME sample); on the other hand, the use of H2O2 alone negatively affected the biogas production. It was demonstrated that the anaerobic biodegradability of OME could be significantly enhanced by pre-treatment using Fentons process and therefore anaerobic degradation after a suitable pre-treatment could be proposed for the safe disposal of OME.

Performance Characteristics of a Pilot Anaerobic Digester Fed by Farmer’s Market Wastes

In this study, anaerobic digestion of farmer’s market waste was studied in the long run and the monitoring of operating parameters is reported to provide detailed operational data for field applications. A continuous feeding of farmer’s market wastes with a dry matter of 5% for 160 days were carried out using a 100 L pilot scale CSTR type anaerobic digester under mesophilic operation conditions. Hydraulic retention time (HRT) and organic loading rate (OLR) were kept around 30 days and less than 3.0 kg oDM/m3.day, respectively. During the 160 days feeding period, daily and volumetric biogas production values were reported to be 20-146 L/day and 0.3-2.0 L/L/day, respectively. This corresponds to an average biogas production 535 L/kg oDM, which means that between 40 and 100 m3 of biogas per wet ton of farmer’s market waste could be produced. In conclusion, this study provides a representative operational data for field application of anaerobic digester running on farmer’s market (mostly fruit and vegetables).