No abstract

Three operational strategies to reduce inhibition due to ammonia during thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste (SS-OFMSW) rich in proteins were investigated. Feed was prepared by diluting SS-OFMSW (ratio of 1:4) with tap water or reactor process water with or without stripping ammonia. Three continuously stirred tank reactors were operated at 55 degrees C with 11.4 gVS d(-1) loading rate and 15 d retention time. Total ammonia nitrogen (TAN) level in the reactor fed with recirculated water alone was spiked to 3.5 and 5.5 g-N l(-1) through ammonium bicarbonate additions. Dilution of SS-OFMSW with fresh water showed a stable performance with volatile fatty acids of < 1g l(-1) and methane yield of 0.40 m3 kg(-1) volatile solids (VS). Use of recirculated process water after stripping ammonia showed even better performance with a methane yield of 0.43 m3 kg(-1) VS. Recirculation of process water alone on the other hand, resulted in process inhibition at both TAN levels of 3.5 and 5.5 g-N l(-1). However, after a short period, the process recovered and adapted to the tested TAN levels. Thus, use of recirculated process water after stripping ammonia would not only evade potential inhibition due to ammonia but could avoid the use of fresh water for dilution of high solids protein-rich SS-OFMSW.

Abstract. Biogas production from sewage sludge digestion is one of the most effective methods for sewage sludge recycling. During the transformation from biogas to biomethane, the unfavorite component must be removed. As a trace amount of undesirable component, the siloxanes in biogas will damage the biogas power generation equipment, which is disadvantage to the biogas utilization. This paper stated the characteristics of siloxanes and the siloxanes removal technologies. The siloxanes removal technologies from biogas, including adsorption on solid material, gas-liquid absorption, condensation, membrane separation, biological treatment, were reviewed and compared. Otherwise, the pre-aeration on anaerobic digestion of sludge was introduced as an alternative for siloxanes removal before digestion.

Abstract-Continuous biohydrogen production process by anaerobic fermentation of glucose was successfully started-up and the average hydrogen yield of 68.6 ml/gcarbohydrate removed was obtained. When the feedstock converted into the mixture of food waste and glucose, the highest hydrogen yield of 77.4 ml-H 2 /g-VS removed in average was achieved at the food waste proportion of 50%. The biogas was not produced any more feeding sole food waste, indicating the failure in the start-up of biohydrogen production process by anaerobic fermentation of food waste by substrate acclimatization.