Elsayed Elbeshbishy

Biochemical methane potential (BMP) of food waste and primary sludge: Influence of inoculum pre-incubation and inoculum source

Biochemical methane potential tests were conducted to evaluate the effect of using a blank versus a pre-incubated inoculum in digestion of primary sludge at different waste to inoculum ratios (S/X). In addition, this study explored the influence of using two different anaerobic inoculum sources on the digestion of food waste: digested sludge from a municipal wastewater treatment plant and from a digester treating the organic fraction of municipal solid wastes. The results revealed that although there was no significant difference in methane yield (on average 114mLCH(4)/g TCOD(sub)) or biodegradability (on average 28.3%) of primary sludge using pre-incubated or non-incubated inocula, the maximum methane production rates using non-incubated inoculum were higher than those using pre-incubated inoculum at all S/X ratios. Moreover, interestingly the inoculum from an anaerobic digester treating municipal wastewater sludge was superior over the inoculum from anaerobic digester treating food waste in digesting food waste.

Comparative assessment of single-stage and two-stage anaerobic digestion for the treatment of thin stillage

A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122 g/L and total volatile fatty acids (TVFAs) of 12 g/L. A maximum methane yield of 0.33 L CH(4)/gCOD(added) (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26 L CH(4)/gCOD(added) (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion.

Optimization of biological hydrogen production for anaerobic co-digestion of food waste and wastewater biosolids.

Batch anaerobic co-digestion studies were conducted using 21 mixtures (M1-M21) of food waste (FW), primary sludge (PS), and waste activated sludge (WAS) at 37°C and an initial pH of 5.5±0.2. The results showed that co-digestion of FW and sludges had a positive impact on the hydrogen production. The maximum hydrogen yields by co-digestion of FW+PS, FW+WAS, and FW+PS+WAS were achieved at volumetric ratios of 75:25, 75:25, and 80:15:5, respectively, with corresponding optimal COD/N mass ratios of 26, 31 and 30, respectively. Furthermore, the synergistic effect of co-digestion was proven and quantified: the measured hydrogen productions were higher than the sums of the hydrogen productions calculated from each fraction, and the highest percentage increase above the calculated value of 101%, was achieved in the FW+PS+WAS mixture (80:15:5).

Comparative study of the effect of ultrasonication on the anaerobic biodegradability of food waste in single and two-stage systems

Five different mesophilic systems were evaluated in this study for the anaerobic treatment of food waste. Systems A and B were one stage methane with unsonicated and sonicated feeds, respectively, while, systems C and D were two-stage hydrogen and methane with unsonicated and sonicated feeds, respectively. System E comprised a novel sonicated biological hydrogen reactor (SBHR) followed by methane reactor. The results showed that sonication inside the reactor in the first stage (system E) showed superior results compared to all other systems. Overall VSS removal efficiencies of 67%, 59%, 51%, 44%, and 36% were achieved in systems E, D, C, B, and A, respectively. Volumetric hydrogen production rates of 4.8, 3.3, and 2.6L H(2)/L(reactor)d were achieved in the SBHR, CSTR with and without sonicated feed, respectively, while, methane production rates of 1.6, 2.1, 2.3, 2.6, and 3.2L CH(4)/L(reactor)d were achieved in systems A-E, respectively.

Hydrogen production from sugar beet juice using an integrated biohydrogen process of dark fermentation and microbial electrolysis cell

An integrated dark fermentation and microbial electrochemical cell (MEC) process was evaluated for hydrogen production from sugar beet juice. Different substrate to inoculum (S/X) ratios were tested for dark fermentation, and the maximum hydrogen yield was 13% of initial COD at the S/X ratio of 2 and 4 for dark fermentation. Hydrogen yield was 12% of initial COD in the MEC using fermentation liquid end products as substrate, and butyrate only accumulated in the MEC. The overall hydrogen production from the integrated biohydrogen process was 25% of initial COD (equivalent to 6 mol H2/mol hexoseadded), and the energy recovery from sugar beet juice was 57% using the combined biohydrogen.

Batch anaerobic co-digestion of proteins and carbohydrates.

Batch anaerobic studies were conducted using five mixtures (M1-M5) of bovine serum albumin (BSA) and starch. The results showed that co-digestion of BSA and starch had a positive impact on the methane production. The highest methane production of 288 mL, the highest methane yield of 360 mL CH(4)/g COD(added), and the highest maximum methane production rate of 62 mL CH(4)/d were achieved for M4 (20% BSA and 80% starch). Most of the particulate proteins (90%) as well as particulate carbohydrates (95%) were degraded in the first 3 days. The hydrolysis coefficients of particulate proteins and particulate carbohydrates ranged from 0.65 to 1.01 d(-1) and from 0.53 to 1.06 d(-1), respectively. The highest methane production was achieved at C:N ratio of 12.8 for M4. For BSA only, propionic acid was the main volatile fatty acid (VFA), while for the starch only, butyric acid was the predominant VFA.

Impact of ultrasonication of hog manure on anaerobic digestability

The efficiency of ultrasonication as a pretreatment method for hog manure prior to anaerobic digestion is evaluated at specific energies of 250-30,000 kJ/kgTS. This study confirmed that COD(solubilisation) from particulates correlated well with the more labor and time intensive degree of disintegration test. The particle size distribution for hog manure was bimodal (0.6-2500 μm), while ultrasonication primarily impacting particles in the 0.6-60 μm range. Hog manure was found to be more amenable to ultrasonication than waste activated sludge, as it took only 3000 kJ/kgTS to cause 15% more solubilization as compared to 25,000 kJ/kgTS for waste activated sludge. Bound protein degradation during sonication was 13.5% at 5000 kJ/kgTS and remained constant thereafter for higher energy input. It was noted that biomass cell rupture occurred at specific energy of 500 kJ/kgTS. An economic evaluation indicated that only a specific energy of 500 kJ/kgTS was economical, with a net energy output valued at

Treatment of thin stillage in a high-rate anaerobic fluidized bed bioreactor (AFBR)

4.1/ton of dry solids, due to a 28% increase in methane production.

Impact of organic loading rate on biohydrogen production in an up-flow anaerobic packed bed reactor (UAnPBR)

The primary objective of this work was to investigate the treatability of thin stillage as a by-product of bioethanol production plants using an anaerobic fluidized bed bioreactor (AFBR) employing zeolite with average diameter of (d(m)) of 425-610 μm and specific surface area (SSA) of 26.5m(2)/g as the carrier media. Despite the very high strength of thin stillage with chemical oxygen demand of 130,000 mg TCOD/L and suspended solids of 47,000 mg TSS/L, the AFBR showed up to 88% TCOD and 78% TSS removal at very high organic and solids loading rates (OLR and SLR) of 29 kg COD/m(3)d and 10.5 kg TSS/m(3)d respectively and hydraulic retention time (HRT) of 3.5 days. Methane production rates of up to 160 L/d at the steady state equivalent to 40 L(CH4)/L(thin stillage)d and biogas production rate per reactor volume of 15.8L(gas)/L(reactor)d were achieved.

Implication of diffusion and significance of anodic pH in nitrogen-recovering microbial electrochemical cells.

This study assesses the impact of organic loading rate on biohydrogen production from glucose in an up-flow anaerobic packed bed reactor (UAnPBR). Two mesophilic UAPBRs (UAnPBR1 and 2) were tested at organic loading rates (OLRs) ranging from 6.5 to 51.4 g COD L(-1)d(-1). To overcome biomass washout, design modifications were made in the UAnPBR2 to include a settling zone to capture the detached biomass. The design modifications in UAnPBR2 increased the average hydrogen yield from 0.98 to 2.0 mol-H2 mol(-1)-glucose at an OLR of 25.7 g COD L(-1)d(-1). Although, a maximum hydrogen production rate of 23.4 ± 0.9 L H2 L(-1)d(-1) was achieved in the UAnPBR2 at an OLR of 51.4 g COD L(-1)d(-1), the hydrogen yield dropped by 50% to around 1 mol-H2 mol(-1)-glucose. The microbiological analysis (PCR/DGGE) showed that the biohydrogen production was due to the presence of the hydrogen and volatile acid producers such as Clostridium beijerinckii, Clostridium butyricum, Megasphaera elsdenii and Propionispira arboris.