Process Enhancement of Hydrogen And Methane Production from Palm Oil Mill Effluent Using Two-Stage Thermophilic and Mesophilic Fermentation

The present study investigates the technical possibilities of hydrogen and methane production from palm oil mill effluent (POME). The production was carried out in two stage (thermophilic and mesophilic) continuous phase with recirculation of the digestate sludge. The reactors used for the present study, up-flow anaerobic sludge blanket reactor (UASB) and continuous stirred tank reactor (CSTR) were operated under thermophilic and mesophilic conditions, respectively. The UASB reactor was operated at 2 days hydraulic retention time (HRT) and 75 kgCOD m3 d−1 organic loading rate (OLR) for hydrogen production. The effluents from UASB reactor containing mainly with acetate and butyrate were directly fed into CSTR for methane production and 5 days HRT was maintained. Both UASB and CSTR reactors were operated for 120 days continuously, and a stable production of the hydrogen and methane was obtained in the separate reactors. The maximum hydrogen and methane production rate achieved was 1.92 L H2 L−d−1 and 3.2 L CH4 L−1 d−1, respectively. The cumulative hydrogen and methane yields were 215 L H2/kgCOD−1 and 320 L CH4/kgCOD−1, respectively with the total COD removal efficiency of 94%. Thermoanaerobacterium species was dominant in hydrogen reactor, while methane reactor was dominated with Methanobrevibacter sp

Wastewater Reclamation in Major Jordanian Industries: A Viable Component of a Circular Economy

Water scarcity remains the major looming challenge that is facing Jordan. Wastewater reclamation is considered as an alternative source of fresh water in semi-arid areas with water shortage or increased consumption. In the present study, the current status of wastewater reclamation and reuse in Jordan was analyzed considering 30 wastewater treatment plants (WWTPs). The assessment was based on the WWWTPs’ treatment processes in Jordan, the flowrates scale, and the effluents’ average total dissolved solid (TDS) contents. Accordingly, 60% of the WWTPs in Jordan used activated sludge as a treatment technology; 30 WWTPs were small scale (<1 × 104 m3/day); and a total of 17.932 million m3 treated wastewater had low TDS (<1000 ppm) that generally can be used in industries with relatively minimal cost of treatment. Moreover, the analysis classified the 26 million m3 groundwater abstraction by major industries in Jordanian governorates. The results showed that the reclaimed wastewater can fully offset the industrial demand of fresh water in Amman, Zarqa, and Aqaba governorates. Hence, the environmental assessment showed positive impacts of reclaimed wastewater reuse scenario in terms of water depletion (saving of 72.55 million m3 groundwater per year) and climate change (17.683 million kg CO2Eq reduction). The energy recovery assessment in the small- and medium-scale WWTPs (<10 × 104 m3/day) revealed that generation of electricity by anaerobic sludge digestion equates potentially to an offset of 0.11–0.53 kWh/m3. Finally, several barriers and prospects were put forth to help the stakeholders when considering entering into an agreement to supply and/or reuse reclaimed water

Integration of solar chimney power plant with photovoltaic for co-cooling, power production, and water desalination

This work explores the technical possibilities of increasing the efficiency of a standard solar chimney power plant (SCPP) by integrating it with photovoltaic (PV) panels. The integration is possible by using the collector circumference to install the PV collectors, which provide a heat sink, allow for the better harvesting of the solar radiation, and increase energy production. The new design led to an increase in the annual electricity production from 380 to 494 MWh and water production from 278 to 326 k tons/year compared with the standard SCPP, marking an increase of 30% and 17%, respectively. The results also show that the integration reduced the greenhouse gas emissions (GHG), the localized cost of energy, and the capital cost of investment by 30%, 36%, and 20%, respectively. The proposed design supports the sustainable replacement of the existing desalination plants with zero operational costs and an excellent reduction in greenhouse gas emissions.The authors would like to the thank the Al Hussien Technical University, Amman, Jordan (www.htu.edu.jo, (accessed on 30 August 2021).) for their support in developing this work.Scopu

Development of Simultaneous Saccharification and Fermentation for Production of Ethanol from Softwood

This thesis deals with the development of simultaneous saccharification and fermentation (SSF) in order to improve the economy of the softwood-to-ethanol process. The effect of process stream recirculation on ethanol production from steam-pretreated softwood based on SSF was investigated for two process cases. In the first case, part of the stillage stream after distillation was recycled and in the second case the liquid after SSF was recycled. The aim was to minimize the energy demand in the distillation of the fermentation broth and in the evaporation of the stillage, as well as the use of fresh water. It was possible to replace of 60% of the fresh water by recirculation of stillage, while maintaining the ethanol yield. This would result in a reduction in the ethanol production cost of 17%. In the second case, where the stream after SSF was recirculated, up to 40% of the fresh water could be replaced without affecting the final ethanol yield, which would result in a 12% reduction in the estimated production cost. Recirculation of the condensates from the evaporation step to SSF could be employed to replace all the fresh water without affecting the ethanol yield. This will make it possible to further reduce the use of fresh water and thereby reduce the volume of wastewater. Increased water-insoluble material (WIM) content in SSF often gives rise to severe inhibition of yeast metabolism due to the increased concentration of toxic compounds formed in the pretreatment step. One way to overcome this problem is to adapt the baker’s yeast to the increased amount of inhibitors in SSF by cultivating it on steam pretreatment hydrolysate. The WIM load was increased from 5 to 8% while maintaining the ethanol yield when the adapted yeast was used in SSF. This could result in a lowering of the production cost by 19%. In order to increase the WIM further, SSF was run in fed-batch mode, using the adapted yeast. Fed-batch SSF with up to10% WIM had no effect on the ethanol yield. A combination of high WIM in fed-batch SSF and recirculation of the process stream will definitely reduce the ethanol production cost. The effect of adding detergent to SSF was investigated using Tween-20, a non-ionic detergent. Tween-20 at 2.5 g/L increased the ethanol yield in SSF by 8%, and could be used to reduce the amount of cellulases required by 50% while maintaining the ethanol yield

Recirculation of process streams in fuel ethanol production from softwood based on simultaneous saccharification and fermentation

The effect of process stream recirculation on ethanol production from steam- pretreated softwood based on simultaneous saccharification and fermentation (SSF) was investigated for two process configurations. In the first configuration, a part of the stillage stream after distillation was recycled and, in the second configuration, the liquid after SSF was recycled. The aim was to minimize the energy consumption in the distillation of the fermentation broth and in the evaporation of the stillage, as well as the use of fresh water. However, recirculation leads to an increased concentration of nonvolatiles in the first configuration, and of both volatiles and nonvolatiles in the second configuration. These substances might be inhibitory to the enzymes and the yeast in SSF. When 60% of the fresh water was replaced by stillage, the ethanol yield and the productivity were the same as for the configuration without recirculation. The ethanol production cost was reduced by 17%. In the second configuration, up to 40% of the fresh water could be replaced without affecting the final ethanol yield, although the initial ethanol productivity decreased. The ethanol production cost was reduced by 12%. At higher degrees of recirculation,fermentation was clearly inhibited, resulting in a decrease in ethanol yield while hydrolysis seemed unaffected

A comparison between batch and fed-batch simultaneous saccharification and fermentation of steam pretreated spruce

In order to improve the process economy it is important to use as high dry matter content as possible in simultaneous saccharification and fermentation (SSF). However, too high dry matter content often gives rise to severe inhibition of the yeast metabolism, due to the increased levels of toxic compounds. The aim of the present work was to increase the fibrous content in SSF of steam pretreated spruce to 10% by adapting the yeast to the inhibitory substrate and by using a fed-batch process. Both batch and fed-batch approaches were evaluated. The fed-batch experiments were started with a batch fermentation containing 6% dry matter. Fibrous slurry from the pretreatment was then added four times during the first 24 h giving a final dry matter content corresponding to 10%. The yeast used in the fermentation was produced aerobically on the hemicellulose hydrolysate obtained from the pretreatment. SSF batch and fed-batch experiments with a cell mass concentration of 2, 3 and 5 g/L were carried out. When adapted yeast was used, the available hexoses were completely converted within 72 h and the final ethanol concentrations reached 40-44 g/L. No major differences in performance between batch and fed-batch were seen, but the ethanol productivity during the first 24 h was higher in the fed-batch SSF experiments, particularly during the experiments with a cell mass concentration of 2 and 3 g/L. (c) 2005 Elsevier Inc. All rights reserved

Influence of strain and cultivation procedure on the performance of simultaneous saccharification and fermentation of steam pretreated spruce

Yeast to be used in simultaneous saccharification and fermentation (SSF) of lignocelluloses materials has to be prepared in a separate cultivation step. The effects of the cultivation procedure on the performance of SSF of steam pretreated softwood were studied in the current work. The yeast used in the SSF was either directly commercially available Baker's yeast (as packaged yeast) or the same strain of yeast produced from the hydrolysate obtained in the pretreatment of the softwood material. A second strain of Saccharomyces cerevisiae TMB3000. isolated from spent sulphite liquor, was also compared with the commercial Baker's yeast. The strains were tested in SSF at substrate loads of 3, 5 and 8% dry weight of water insoluble material. Final ethanol yields were above 85% of the theoretical (based on the available hexoses) in all cases, except for the package yeast for the 8% substrate load, in which case the final yield was less than 65%. The cultivation procedure was found to have a significant impact on the performance during SSF, as well as in small-scale fermentations of hydrolysate liquor without solid material. The Baker's yeast cultivated on the hydrolysate from the steam pretreatment had in all cases a higher productivity, in particular at the highest substrate load. Cultivated Baker's yeast had a slightly higher productivity than TMB3000. The results suggest that the adaptation of the yeast to the inhibitors present in the medium is an important factor that must be considered in the design of SSF processes

Energy and Economic Analysis of Date Palm Biomass Feedstock for Biofuel Production in UAE: Pyrolysis, Gasification and Fermentation

This work evaluates date palm waste as a cheap and available biomass feedstock in UAE for the production of biofuels. The thermochemical and biochemical routes including pyrolysis, gasification, and fermentation were investigated. Simulations were done to produce biofuels from biomass via Aspen Plus v.10. The simulation results showed that for a tonne of biomass feed, gasification produced 56 kg of hydrogen and fermentation yielded 233 kg of ethanol. Process energy requirements, however, proved to offset the bioethanol product value. For 1 tonne of biomass feed, the net duty for pyrolysis was 37 kJ, for gasification was 725 kJ, and for fermentation was 7481.5 kJ. Furthermore, for 1 tonne of date palm waste feed, pyrolysis generated a returned USD $768, gasification generated USD 166, but fermentation required an expenditure of USD 763, rendering it unfeasible. The fermentation economic analysis showed that reducing the system&rsquo;s net duty to 6500 kJ/tonne biomass and converting 30% hemicellulose along with the cellulose content will result in a breakeven bioethanol fuel price of 1.85 USD/L. This fuel price falls within the acceptable 0.8&ndash;2.4 USD/L commercial feasibility range and is competitive with bioethanol produced in other processes. The economic analysis indicated that pyrolysis and gasification are economically more feasible than fermentation. To maximize profits, the wasted hemicellulose and lignin from fermentation are proposed to be used in thermochemical processes for further fuel production

A Novel Design of a Hybrid Solar Double-Chimney Power Plant for Generating Electricity and Distilled Water

The classical solar chimney offers passive electricity and water production at a low operating cost. However, the solar chimney suffers from high capital cost and low energy output density per construction area. The high capital investment increases the levelized cost of energy (LCOE), making the design less economically competitive versus other solar technologies. This work presents a new noteworthy solar chimney design for high energy density and maximizing water production. This was achieved by integrating a cooling tower with the solar chimney and optimizing the operating mood. The new design operated day and night as a hybrid solar double-chimney power plant (HSDCPP) for continuous electricity and water production. During the daytime, the HSDCPP operated as a cooling tower and solar chimney, while during the night, it operated as a cooling tower. The annual energy output from the cooling towers and solar chimney (i.e., the HSDCPP) totaled 1,457,423 kWh. The annual energy production from the cooling towers alone was 1,077,134 kWh, while the solar chimney produced 380,289 kWh. The annual energy production of the HSDCPP was ~3.83-fold greater than that of a traditional solar chimney (380,289 kWh). Furthermore, the HSDCPP produced 172,344 tons of fresh water per year, compared with zero tons in a traditional solar chimney. This led to lower overall capital expenditures maximizing energy production and lower LCOE

Integration of Solar Chimney Power Plant with Photovoltaic for Co-Cooling, Power Production, and Water Desalination

This work explores the technical possibilities of increasing the efficiency of a standard solar chimney power plant (SCPP) by integrating it with photovoltaic (PV) panels. The integration is possible by using the collector circumference to install the PV collectors, which provide a heat sink, allow for the better harvesting of the solar radiation, and increase energy production. The new design led to an increase in the annual electricity production from 380 to 494 MWh and water production from 278 to 326 k tons/year compared with the standard SCPP, marking an increase of 30% and 17%, respectively. The results also show that the integration reduced the greenhouse gas emissions (GHG), the localized cost of energy, and the capital cost of investment by 30%, 36%, and 20%, respectively. The proposed design supports the sustainable replacement of the existing desalination plants with zero operational costs and an excellent reduction in greenhouse gas emissions