Experiments were conducted to select a natural mixed microflora seed source and investigate the effect of temperature and pH on fermentative hydrogen (H2) production from cattle wastewater by sewage sludge. Sewage sludge was shown to have higher cumulative H2 production than other inoculum collected from cow dung compost, chicken manure compost, and river sludge. Experimental results show that H2 production from cattle wastewater was significantly affected by both pH and temperature of the culture. The maximum H2 yield was obtained at pH 5.5. H2 yield and the ratio of butyrate/acetate (Bu/Ac) followed a similar production trend, suggesting that butyrate formation might favor H2 production. The optimal temperature for H2 production from cattle wastewater was 45 degrees C with peak values of H2 production (368 ml), hydrogen yield of 319 ml H2/g chemical oxygen demand (COD) consumed, and butyrate/acetate ratio of 1.43. Presence of ethanol and propionic acid indicated decreased hydrogen production; their concentrations were also affected by pH and temperature. A modified Gompertz model adequately described H2 production and bacterial growth.
"To overcome the stated problems, farmers apply fertilizers excessively to attain higher yield. However, unbalanced use of N and P fertilizers causes environmental problems such as eutrophication , groundwater pollution, acid rain deposition, soil acidification, and greenhouse gas emissions    . "
[Show abstract][Hide abstract] ABSTRACT: High cation exchange capacity and organic matter content of crude humic substances from compost could be exploited to reduce ammonia loss from urea and to as well improve rice growth and soil chemical properties for efficient nutrients utilization in lowland rice cultivation. Close-dynamic air flow system was used to determine the effects of crude humic substances on ammonia volatilization. A pot experiment was conducted to determine the effects of crude humic substances on rice plant growth, nutrients uptake, nutrients recovery, and soil chemical properties using an acid soil mixed with three rates of crude humic substances (20, 40, and 60 g pot−1). Standard procedures were used to evaluate rice plant dry matter production, nutrients uptake, nutrients recovery, and soil chemical properties. Application of crude humic substances increased ammonia volatilization. However, the lowest rate of crude humic substances (20 g pot−1) significantly improved total dry matter, nutrients uptake, nutrients recovery, and soil nutrients availability compared with crude humic substances (40 and 60 g pot−1) and the normal fertilization. Apart from improving growth of rice plants, crude humic substances can be used to ameliorate acid soils in rice cultivation. The findings of this study are being validated in our ongoing field trials.
"Throughout the 5 day (static) fermentation, gas pressure was measured once a day using a digital manometer fitted with a syringe needle to determine biogas production, while gas samples (500 mL) were taken for hydrogen analysis. Subsequent fermentation experiments were conducted using the best pretreatment method and the conditions in Table 2. Since temperature and pH were reported to be critical parameters in the efficiency of biohydrogen production  , a factorial experiment was used to evaluate their impacts . Then, a study on biomass loading followed to evaluate high solids/high salts concentration using the optimum combination of temperature and initial pH determined previously . "
[Show abstract][Hide abstract] ABSTRACT: Duckweed harvested from a swine wastewater treatment system was evaluated for its potential as a fermentation feedstock for the production of biohydrogen. The effects of pretreatment and fermentation conditions on biohydrogen production were investigated in laboratory-scale batch experiments. The results showed that mild acidic thermal pretreatment (1% H2SO4 and 85 °C for 1 h) was more effective in improving the fermentability of duckweed than either thermal or mild alkaline thermal pretreatments. Fermentation of acid-pretreated duckweed resulted in a biohydrogen production of up to 75 mL H2 per g dry duckweed in 7 days (at a H2 concentration of 42%), which is comparable with other plant biomass. Overall, the results show that small aquatic plants such as duckweed can be promising substrate for biohydrogen production.
International Journal of Hydrogen Energy 04/2015; 40(22). DOI:10.1016/j.ijhydene.2015.03.166 · 3.31 Impact Factor
"However, there was little information on hydrogen production from OPEFB biomass hydrolyzate which is composed mainly of simple carbohydrate. Typically, the fermentation of biomass hydrolyzate, that uses wastewater sludge as inoculums, is influenced by parameters such as pH, temperature and substrate specificity . The perception of the hydrogen production under different operational condition is extraordinarily narrowed, particularly with the use of mixed culture. "
[Show abstract][Hide abstract] ABSTRACT: a b s t r a c t Carbohydrates from hydrolyzed biomass has been a potential feedstock for fermentative hydrogen production. In this study, oil palm empty fruit bunch (OPEFB) was treated by sulfuric acid in different concentrations at 120 C for 15 min in the autoclave. The optimal condition for pretreatment was obtained when OPEFB was hydrolyzing at 6% (w/v) sulfuric acid concentration, which gave the highest total sugar of 26.89 g/L and 78.51% of sugar production yield. However, the best conversion efficiency of OPEFB pretreatment was 39.47 at sulfuric acid concentration of 4%. A series of batch fermentation were performed to determine the effect of pH in fermentation media and the potential of this prehydrolysate was used as a substrate for fermentative hydrogen production under optimum pretreat-ment conditions. The prehydrolysate of OPEFB was efficiently converted to hydrogen via fermentation by acclimatized mixed consortia. The maximum hydrogen production was 690 mL H 2 L À1 medium, which corresponded to the yield of 1.98 molH 2 /mol xylose achieved at pH 5.5 with initial total sugar concentration of 5 g/L. Therefore, the results implied that OPEFB prehydrolysate is prospective substrate for efficient fermentative hydrogen con-ducted at low controlled pH. No methane gas was detected throughout the fermentation.
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