Effects of different pretreatment methods on anaerobic mixed microflora for hydrogen production and COD reduction from palm oil mill effluent

Abstract

a b s t r a c tEffects of different pretreatment methods on sludge inocula were evaluated with respect to hydrogen (H 2 ) production enhancement using palm oil mill effluent (POME) in a batch system. The experimental results showed that the pretreatment methods (chemical, acid, heat-shock, freezing and thawing, and base) at 35 C and initial pH 5.5 had a positive influence on H 2 production yield and chemical oxygen demand (COD) removal efficiency during the fermentative H 2 production as compared to the control experiments (without pretreatment). Heat-shock pretreatment method was shown to be a simple and useful method for enhancing both H 2 producing and COD removal processes from POME with highest H 2 yield and COD removal efficiency at 0.41 mmol H 2 /g COD and 86%, respectively.

Effects of pre-treatment technologies on dark fermentative biohydrogen production: A review

“…Subsequently, high H 2 yields have been reported by Mohammadi et al (2011Mohammadi et al ( , 2012. Most of the studies on the effects of freezing and thawing have used a freezing time of 24 h with the freezing temperature varying from À25 C to À10 C (Mohammadi et al, 2011(Mohammadi et al, , 2012Liu et al, 2009;Toscano et al, 2014).…”

“…Subsequently, high H 2 yields have been reported by Mohammadi et al (2011Mohammadi et al ( , 2012. Most of the studies on the effects of freezing and thawing have used a freezing time of 24 h with the freezing temperature varying from À25 C to À10 C (Mohammadi et al, 2011(Mohammadi et al, , 2012Liu et al, 2009;Toscano et al, 2014). As for the thawing process, the time investigated has varied from 5 h to the time required for the pre-treated sample to reach room temperature with the thawing temperature varying from 25 C to 30 C or at room temperature Mohammadi et al, 2012;Dong et al, 2010;Pita and P erez, 2011).…”

“…Various conditions have been investigated for acid and base pretreatment whereby the acids employed are HCl, H 2 SO 4 , HNO 3 and HClO 4 Cheong and Hansen, 2006) while the acid concentrations have ranged from 0.1 to 6.0 M Hu and Chen, 2007;Mohammadi et al, 2011Mohammadi et al, , 2012 with pH varying from 2.0 to 4.0 Lee et al, 2009;Chaganti et al, 2012). For alkaline pre-treatment, NaOH has been the most commonly used alkali with concentrations varying from 1.0 to 8.0 M and pH from 10.0 to 12.0 Mohammadi et al, 2011Mohammadi et al, , 2012Pita and P erez, 2011) although Pendyala et al (2012) used KOH for alkaline pre-treatment.…”

“…For alkaline pre-treatment, NaOH has been the most commonly used alkali with concentrations varying from 1.0 to 8.0 M and pH from 10.0 to 12.0 Mohammadi et al, 2011Mohammadi et al, , 2012Pita and P erez, 2011) although Pendyala et al (2012) used KOH for alkaline pre-treatment. The most commonly employed retention time in either acidic or basic pre-treatment is 24 h as confirmed from Table 4.…”

Improved microbial conversion of de-oiled Jatropha waste into biohydrogen via inoculum pretreatment: process optimization by experimental design approach

“…To obtain such bacterial populations, the seed pretreatment is often a key step. Nevertheless, the most appropriate technique to enrich the hydrogen-producing strains has to be found specifically for each case due to the diversities in the microbial population structure of seed sources of different origins (Mohammadi et al, 2011;Wang et al, 2011). In addition to the importance of seed pretreatment, it is also known that biotechnological hydrogen formation is influenced by the environmental conditions applied.…”