Anaerobic acidification of sugar-beet processing wastes: Effect of operational parameters

Alkaya, Emrah
Demirer, Göksel Niyazi
The objective of this study was to maximize the hydrolysis and acidification of sugar-beet processing wastewater and beet pulp for volatile fatty acid (VFA) production through acidogenic anaerobic metabolism. Experiments were conducted to determine the optimum operational conditions (HRT, waste-mixing ratio and pH) for effective acidification in daily-fed, continuously mixed anaerobic reactors. For this purpose, reactors were operated at 35 +/- 1 degrees C with different combinations of HRT (2-4 days), wastewater-pulp mixing ratios (1:0-1:1, in terms of COD) and pH ranges (5.7-7.5). Increased OLRs, resulting from pulp addition, increased the amount of acidification products (VFAs) which led to relatively low operational pH values (5.7-6.8). In this pH range, methanogenic activity was successfully inhibited and the lowest methane percentages (5.6-16.3%) were observed in the produced biogas. The optimum operational conditions were determined to be 2-day HRT and 1:1 waste mixing ratio (in terms of COD) without external alkalinity addition. These operational conditions led to the highest tVFA concentration (3635 +/- 209 mg/L as H-Ac) with the acidification degree of 46.9 +/- 2.1%.


Anaerobic biogasification of undiluted dairy manure in leaching bed reactors
Demirer, Göksel Niyazi; Chen, S. (Elsevier BV, 2008-01-01)
Dry anaerobic digestion of high solids animal manure is of increasing importance since conventional slurry digestion is not an effective system for these manures. The investment costs for large-size reactors, costs for heating these reactors, handling, dewatering, and the disposal of the digested residue decrease the benefits of conventional slurry anaerobic digestion for high solids animal manure. Even though leaching bed reactors (LBR) constitute a promising option for dry anaerobic biogasification of ani...
Anaerobic mesophilic digestion of waste activated sludge in the presence of 2,3 ',4,4 ',5-pentachlorobiphenyl
Kaya, Devrim; İmamoğlu, İpek; Sanin, Faika Dilek (Elsevier BV, 2013-09-01)
The aim of this study was to investigate the anaerobic digestion of waste activated sludge in the presence of a model PCB congener, 2,3',4,4',5-pentachlorobiphenyl (PCB-118), and transformer oil (TO), and thereby PCB dechlorination under mesophilic digestion conditions. Two PCB-118 concentrations (1 and 20 mg/L) and one TO concentration (1.52 g/L) were studied. Beside the PCB concentrations, pH, ORP, TS, VS, VSS, TSS, tCOD, and sCOD were monitored throughout the reactor operations (159-day). Methane product...
Anaerobic mesophilic co-digestion of sugar-beet processing wastewater and beet-pulp in batch reactors
Alkaya, Emrah; Demirer, Göksel Niyazi (2011-03-01)
In this study, biochemical methane potential (BMP) assay was conducted to investigate the effect of waste mixing and F/M ratio on the co-digestion of wastewater and beet-pulp, in addition to the digestion of the wastes separately. In the studied F/M range (0.51–2.56 g COD/g VSS), observed treatment efficiencies (63.7–87.3% COD removal and 69.6–89.3% VS reduction) were indications of high biodegradability for both wastewater and beet-pulp, which decreased with increasing F/M. It was evident that the extent o...
Ionic liquid pretreatment allows utilization of high substrate loadings in enzymatic hydrolysis of biomass to produce ethanol from cotton stalks
Haykir, Nazife Isik; Bakir, Ufuk (Elsevier BV, 2013-11-01)
To enhance the enzymatic conversion of cotton stalks to glucose at high substrate loadings and subsequently to produce ethanol, biomass was subjected to ionic liquid and alkaline pretreatments. Ionic liquid, 1-ethyl-3-methylimidazolium acetate (EMIMAc), which reduced biomass crystallinity, was effective in improving the conversion of cotton stalks to glucose (82-85%) regardless of the substrate loading used during enzymatic hydrolysis. On the other hand, the glucose yield decreased from 67% to 55% with an i...
Fermentation and oxygen transfer characteristics in serine alkaline protease production by recombinant Bacillus subtilis in molasses-based complex medium
Calik, G; Pehlivan, N; Ozcelik, IS; Çalık, Pınar; Ozdamar, TH (Wiley, 2004-11-01)
Serine alkaline protease (SAP) production in a complex medium based on physically pretreated molasses by recombinant Bacillus subtilis carrying pHV1431::subC gene is described. The effects of oxygen transfer were investigated in 3.5 dm(3) bioreactor systems with controls for agitation rate, dissolved oxygen, pH, temperature, and foam formation under two different agitation rates, ie N = 500 and 750 min(-1), and four different air flow rates, ie Q/V-R = 0.2, 0.5, 0.7, and 1.0 vvm, at a molasses concentration...
Citation Formats
E. Alkaya and G. N. Demirer, “Anaerobic acidification of sugar-beet processing wastes: Effect of operational parameters,” BIOMASS & BIOENERGY, pp. 32–39, 2011, Accessed: 00, 2020. [Online]. Available: