Anaerobic co digestion of tea powder waste and carbon rich organic waste with sewage sludge for biomethane production

Abstract

Anaerobic digestion of Municipal Organic Solid Waste (MOSW) is the need of an hour for environmental protection coupled with energy generation. This research study provides experimental evidence on the utilization of filtered Tea powder waste (TPW) as a potential co-substrate for an enhanced biomethane production. This work also focused on improving the efficiency of anaerobic co-digestion of Food, Fruit, and vegetable waste (FFV), TPW with sewage treatment plant sludge (STP, as inoculum) for biomethane production. The study evaluated and optimized the temperature and waste maxing ratio for the enhanced biomethane yield of filtered tea powder codigested with FFV, using the standard Biochemical Methane Potential (BMP) assay test. The study quantified the physical composition, proximate and ultimate characteristics of the filtered tea powder waste and the carbon-rich organic waste together with the stoichiometric methane potential and calorific energy value. Methanogens in the sludge were enriched by adding freshly-prepared micronutrients, and pH was adjusted to 7.5±0.2. The enriched sludge is named as Methanogen Enriched anaerobic seed Sludge (MES), which was considered as inoculum for the AD process. Biochemical methane potential (BMP) test of mono and co-digesters was carried out under three different operating temperatures using the MES (35 °C, 45 °C, and 55 and#7506;C) to identify the optimum feed ratio (FFV: TPW: MES) and to know the effect of increased temperature kinetics for 60 days degradation time. Simultaneously, the changes in process parameters such as pH, VFA, SCOD, and alkalinity were analyzed during theanaerobic batch process for the mentioned temperatures. The optimum pH range (6-7.5) and high SCOD removal of 93% was obtained at35 °C and moderate to high fluctuations in process parameters were recorded under 45 °C and 55 °C, respectively. The daily and cumulative methane production of mono-digestion and co-digestion feed ratio was estimated from the batch experiments under three different temperatures.