Optimized operational parameters of anaerobic cellulosic-wastewater treatment for bioenergy recovery and effluent quality improvements (original) (raw)
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International Journal of Renewable Energy Research, 2013
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BioResources, 2014
The methane potential and influence of the inoculum to substrate ratio of wastewater originating from the production of microcrystalline cellulose (MCC) were studied. Laboratory experiments were carried out in a continuously stirred batch multi-reactor at mesophilic temperature (37 °C). Inoculum to substrate ratios (ISRs) of 2.0, 1.0, 0.8, and 0.5 based on volatile solids (VS) were evaluated. The results demonstrate the suitability of MCC wastewater at ISRs of 2.0, 1.0, and 0.8 with ultimate methane potentials of 333, 297, and 325 mL CH4 per gram of volatile solids added, respectively, which correspond to anaerobic degradabilities of 91.4, 81.7, and 89.3%, respectively, compared to the theoretical potential. The inoculum to substrate ratio of 2.0 provided a faster methane production rate and a kinetic constant of 0.24 d -1 , reaching its ultimate yield at day 8 of incubation. The lowest ISR of 0.5 showed the occurrence of process inhibition due to accumulation of acids. Energy estimation suggests that considering the volume and VS of wastewater produced in a MCC mill, a total energy amount of 44,105 GJ/year can be produced, which can be used to replace 29.4% of the natural gas demand.
Recent Developments in Biogas Production from Pulp and Paper Industry Wastewaters
Increase in population and rapid developments in technology have enhanced production capacity in pulp and paper industry and have resulted in formation of huge amount of wastewaters, as high as 6-15 x 10 4 L per ton of paper produced. Depending on the pulping process, wastewaters can have a wide range of various pollutants characterized by biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), toxicity, and dark color. Untreated wastewaters from pulp and paper can be potentially very polluting especially for high COD concentrations which can be reach at 13000 mg/L. Thus a reliable treatment process is needed to reduce any possible impacts of wastewaters on the receiving media. To overcome this problem an environmentally friendly and economically viable treatment technology should be applied. Indeed, high organic content of pulp and paper industry wastewaters make anaerobic treatment a very attractive option for these wastes. Anaerobic processes not onl...
Water Science and Technology, 2011
Anaerobic digestion is an effective technology to convert cellulosic wastes to methane and hydrogen. Heat-treatment is a well known method to inhibit hydrogen-consuming bacteria in using anaerobic mixed cultures for seeding. This study aims to investigate the effects of heat-treatment temperature and time on activated sludge for fermentative hydrogen production from α-cellulose by response surface methodology. Hydrogen and methane production was evaluated based on the production rate and yield (the ability of converting cellulose into hydrogen and methane) with heat-treated sludge as the seed at various temperatures (60–97°C) and times (20–60 min). Batch experiments were conducted at 55°C and initial pH of 8.0. The results indicate that hydrogen and methane production yields peaked at 4.3 mmol H2/g cellulose and 11.6 mmol CH4/g cellulose using the seed activated sludge that was thermally treated at 60°C for 40 min. These parameter values are higher than those of no-treatment seed (H...
2019
Anaerobic co-digestion was carried out at mesophilic condition (37°C) in 1-L media bottles with a working volume of 800 mL consisting of different dilution ratio of distillery wastewater (DWW), press mud, bagasse, and inoculum. Distillery waste water was diluted with tap water at two different ratios (2:3 and 3:2) and in two sample bottles, micronutrients were added. Batch test results showed that press mud mixed with diluted distillery wastewater with and without additional micronutrients gave the highest methane yield of 61.3% and 78.23% (v/v), respectively. Methane yield is affected by the sensitivity of microorganisms to pH variations. In this study, optimum pH was found out to be 5.0 to maximize methane yield. COD/BOD ratio was also evaluated and the optimum initial COD to BOD ratio of the sample that yields higher methane yield ranged from 1.8 to 2.6 which indicate that it is amenable to biological treatment. Meanwhile, the optimum C/N ratio is found to be in the range of 72:1 and 78:1. For the effect of dilution, higher methane yield occurred at higher dilution ratio. Moreover, anaerobic co-digestion of organic sugar waste was more favorable in biogas production compared to mono-digestion of a single biomass. Lastly, effect of micronutrients to the digestion and heterotrophic plate count were evaluated in this study.
A study on the starch and cellulose industries’ wastewater treatment by biological methods
Waste Management and the Environment IV, 2008
Since the wastewater produced by the starch and cellulose industries has a high level of COD and turbidity, there are various methods for their treatment, one of which is a biological treatment method such as constructed wetlands. In this method, the plants are planted in sand or other different media. It is better that these media have a uniform constancy and the influent and effluent flow to the system and the residence time of wastewater in the biological system must also be adjusted. By increasing the residence time, the elimination rate of COD and turbidity will be increased. As a rule, if it is not possible to increase the residence time, increasing the efficient surface or vegetation accumulation will be better. This project has been carried out from May 1998 to May 1999. Results showed reed (Phragmites spp.) planted wetland as having the ability to treat starch and cellulose industry wastewater. The mean value of COD in the constructed wetland effluent was 93.17mg/L (78% removal) and the values of turbidity, nitrite and pH were 23.04 NTU, 0.19 mg/L and 7.5 respectively. Turbidity removal ranged from 73-98% and the removal of nitrite ranged from 10-55%. The efficiency of the reed planted wetland for treating the above mentioned wastewater was reasonable and in good operational conditions its effluent could be used in agricultural irrigation or discharged into surface water or leaching pits.