Sludge Acclimation, And Pretreatment Of The Impact Of Fermentative Hydrogen Production On Apple Pomace

Energy shortage and environmental pollution are two main problems for our humans currently. Many attentions has been paid on the investigation of new energy resources such as, nuclear energy, solar energy, geothermal energy, wind energy, hydrogen energy etc. Hydrogen is much more outstanding owe to the advantages of widely available, clean, high combustion heat. Many methods have been applied to produce hydrogen, including thermocatalytic reforming of H2-rich organic compound, electrolysis of water and biological processes. Among these methods, fermentative hydrogen production is more attractive because it is low cost and a feasible way for waste recovery while the instrument is simple and the operation is convenient.In this work, apple residue was choosen as the fermentative substate which was collected from Xi'an juice factory. The activated sludge from Xi'an sewage plant was used as inoculum source. In order to enhance the biohydrogen process, the sludge was pretreated by various approaches (domestication, boiling, ultraviolet,ultrasonic etc) before mixed with the apple residue in fermenative experiments. The results were evalusted by the cumulative hydrogen yield (CHY) and average hydrogen producion rate (AHPR). In addition, the fermentative mechanism was also explored by the addition of organic acids into the fermentative system.A series of batch experiments were conducted to study the effects of various sludge pretreatments (domestication, boiling, acid and alkali) on the fermentative H2 production from apple residue. The sludge domestication process markedly shortens the H2-producing lag time, and H2 gas was produced only 5 min after mixing the sludge and substrate. The results show that the boiling pretreatment of the sludge is better than the acid and alkali pretreatments in enhancing hydrogen yield from apple residue. The best domestication and boiling time for the sludge were 6 h and 30 min, respectively and gave the maximum cumulative H2 yield of 94.68 ml·g-1-TS with an average H2 production rate of 9.02 ml·g-1-TS·h-1 at the fermentation temperature (37℃), initial pH (7.0) and substrate concentrate (20 g/L).Using apple pomace (AP) as substrate, the effects of ultraviolet and ultrasonic pretreatments of activated sludge on anaerobic fermentative bio-H2 production were studied. The results show that a maximum cumulative H2 production (CHPm) of 106.93 ml g-1-TS and an average H2 production rate (AHPR) of 14.97 ml g-1-TS h-1 were obtained with the activated sludge was irradiated by ultraviolet lamp (25 w) for 15 min. In contrast, the optimal time for ultrasonic pretreatment is 30 min with CHPm (104.43 mL·g-1-TS) and AHPR (18.42 mL·-1 g-TS·h-1). Furthermore, no methane was detected during the fermentative hydrogen production process. Based on the optimal sludge pretreatment method, the effect of micro-addition of various organic acids on the hydrogen-producing fermentation was also systematically investigated.