The success of enhanced biological phosphorus removal depends on the constant availability of volatile fatty acids (VFAs). To reduce costs of purchasing external carbon, waste streams would be a preferred source for nutrient removal. VFAs were shown to vary in the incoming sewage and fermentate from primary sludge (PS). Another available source of organic to generate VFAs is waste activated sludge (WAS). The effect of solids retention time and biomass concentration, as well as the effect of temperature and requirement for mixing on generation of VFA from the fermentation of WAS were investigated. It was found that VFA yields from sludge fermentation increased with SRT. At the longest SRT of 10 days improved biomass degradation resulted in the highest soluble to total COD ratio and the highest VFA yield. WAS fermentation was found highly temperature-dependent. The overall VFA–COD concentration in the non-mixed reactors was much lower than the mixed reactors. The study of fermentation of PS, WAS and a mixture of WAS and PS demonstrated that PS fermentation predictably generated a significantly higher amount of soluble COD than WAS. Co-fermentation of WAS with PS enhanced soluble COD production and increased the release of phosphate and ammonium. Fermentation of combined PS and WAS sludge generated a concentration of phosphate high enough to allow phosphorus recovery as struvite The effect of using glycerol as an external carbon source in biological phosphorus removal was investigated. Using glycerol directly resulted in the failure of the process which maintained enhanced biological phosphorus removal. When glycerol was co-fermented with waste activated sludge, significant VFA production was observed. By 2 | P a g e supplying the system with the VFA-enriched supernatant of the fermentate, biological phosphorus removal was enhanced. It was concluded that, if glycerol was to be used as external carbon source for biological phosphorous removal, the effective approach was to ferment glycerol with waste activated sludge. According to the cost analysis, the economic benefit of WAS fermentation can be demonstrated in three ways: 1) cost saving in external carbon addition; 2) cost saving in sludge handling; 3) revenue from phosphorus. At current condition, the value of the recovered P product is insignificant relative to the cost of chemicals that required for recovery and capital cost of the facilities. However, P recovery becomes important when the sustainability take into account.

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The conversion of soybeans to tempe is achieved through fermentation by Rhizopus. This fermentation process leads to hydrolysis of both proteins and lipids. The present work investigated certain biochemical changes which accompany the conversion of soybeans to tempe. The contents of non-protein nitrogen and free $ alpha$-amino nitrogen increased from 2.34 to 15.14%, and 2.03 to 5.22%, respectively after 48 h fermentation. SDS electrophoresis showed that a substantial quantity of the proteins in raw soybeans were hydrolysed by the Rhizopus to low molecular species (molecular weight $<$13,000 Daltons). Trypsin inhibitor activity found in tempe was lower than that of soybean and soaked soybean (an intermediate step in tempe preparation). The protein digestibilities of tempe and soaked soybean were higher than that of soybean. Reversed phase HPLC showed that the peptide separation profile of tempe was different from that of soybean and soaked soybean. The ESI/MS of the RP-HPLC fractions gave molecular weight of soybean peptides ranging from 1962 Da to 22,699 Da and tempe peptides ranging from 569 Da to 16,688 Da. The fatty acid compositions of tempe, soybean and soaked soybean were similar; relatively high levels of linoleic acid followed by oleic, linolenic and stearic acids were found. The acid values increased from 1.49 to 11.42 during the fermentation of soybeans. The total soluble carbohydrate contents of soybean, tempe and soaked soybean as well as the types and quantities of individual sugars were similar. The fermentation of soybean by Rhizopus had only a minor effect on the proximate composition of soybean; however, the soybean and fungal enzymes contributed primarily to changes in protein composition.

Graduation date: 1955