Effluent Recycling Research Articles

Enhancing physico-chemical water quality in recycled dairy effluent through microbial consortium treatment

The dairy industry, notorious by generating wastewater rich in organic and nitrogenous content, necessitates sustainable recycling solutions. Biological treatment emerges as a cost-effective and chemical-free alternative. This study delves into the potential of microbial consortium, a microbial consortium, for recycling dairy effluent, aiming at water reclamation and environmental sustainability. Effluent samples from Madurai's Dairy Industry underwent microbial consortium treatment in a recycling prototype, with treatment efficacy assessed through physicochemical parameters and contaminant removal efficiency.Guided by a biodegradability index of 4.51, the study showcased EM's impact, revealing a notable decrease in pH levels, fostering an alkaline environment (2.35 ± 0.06 ppt). Dissolved oxygen increased significantly to 4.50 ppm, indicating improved aerobic conditions. EM treatment led to substantial reductions in calcium (53 %), magnesium (95 %), nitrogen (22 %), sulfate (79 %), phosphate (86 %), BOD (78 %), and COD (82 %). In contrast, dairy effluent treated without microbial consortium during the sludge activation process exhibited negligible water quality improvement.These findings underscore microbial consortium efficacy in advancing biological treatment of dairy effluent, demonstrating a significant reduction in contaminants and showcasing its potential for sustainable water reclamation. Improved alkalinity, dissolved oxygen, and nutrient content further signify positive impacts on ecosystem health. Microbial consortium emerges as a promising avenue for recycling dairy effluent, offering an economically viable and environmentally friendly solution. The study emphasizes the crucial role of microbial treatments in achieving efficient water reclamation, contributing to a cleaner and sustainable environment. Future research and broader implementation of microbial consortium in dairy industry wastewater management are recommended for enhanced environmental benefits.

Use of microalgal-fungal pellets for hydroponics effluent recycling and high-value biomass production

Hydroponic effluent (HE), enriched with inorganic nutrients, presents a viable, low-cost cultivation medium for microalgal biomass production and subsequent resource recovery. However, downstream processing, particularly biomass harvesting, remains a critical challenge for microalgal biorefineries. Therefore, the present study explored the potential of microalgal-fungal pellets (MAFP) in HE recycling for the production of biochemical-rich biomass. The optimized fungi-to-microalgae ratio (F:A) of 1:3 resulted in 100 % microalgal pelletization within 6 h. Surface characteristics suggested that metabolically active fungi with opposite charges facilitate microalgal pelletization. Further, MAFP exhibited a packed porous structure that was resilient to shear forces and had a high capacity for nutrient uptake. MAFP cultivation in HE demonstrated complete removal of ammonia-nitrogen (NH₃-N), phosphate (PO₄³⁻), and nitrate-nitrogen (NO₃⁻-N) within 7–9 days. The produced biomass was rich in biomolecules, including lipids (18.36 ± 0.12 % TS), protein (52.06 ± 2.1 % TS), and carbohydrates (28.95 ± 0.05 % TS). Besides, the high methane potential of MAFP (SMP ≈ 502.74 ± 19.1 mL CH4 g−1 VS, and TMP ≈ 817.68 ± 12.5 mL CH4 g−1 VS) indicated its suitability for biogas production. In essence, MAFP offers efficient HE recycling and biochemically rich biomass production, advancing towards a green and circular bioeconomy.

Effect of hydraulic retention time and effluent recycle ratio on biogas production from POME using UASB-HCPB fermentor assisted with ultrafiltration membrane at mesophilic condition

Biogas is renewable energy produced through anaerobic digestion based on palm oil mill effluent. Biogas production is overgrowing and is carried out in various bioreactors, such as the Upflow Anaerobic Sludge Blanket - Hollow Centered Packed Bed fermentor. Even though this process is considered successful in producing biogas, it has not adopted a recycling system. Therefore, the remaining sludge (effluent) after the processing process is generally not reused and is thrown into the environment, which still has the opportunity to produce biogas. The combination of the performance of the the Upflow Anaerobic Sludge Blanket - Hollow Centered Packed Bed fermentor with an ultrafiltration membrane is one of the latest innovations to reduce the volume of effluent wasted through recycling the effluent (retentate) into the feed tank. This research aims to produce biogas from liquid waste from palm oil mills using an Up-flow Anaerobic Sludge Blanket-Hollow Centered Packed Bed fermentor combined with ultrafiltration membranes under mesophilic conditions. In this research examines the effect of hydraulic retention time and the effluent recycling ratio on the pH profile, alkalinity, production, biogas composition, and kinetics of biogas production. The research began with loading up by varying the hydraulic retention time, namely 40, 25, and 10, until reaching the target hydraulic retention time of 6 days in a 5.4 L fermentor with a pH of 7 ± 0.2 under mesophilic conditions. Next, the effect of the recycling ratio was studied by varying the effluent (retentate) recycling ratio, namely 0, 15, and 25 %. The parameters analyzed are pH, M-Alkalinity, total solids, volatile solids, total suspended solids, volatile suspended solids, chemical oxygen demand, volume, and biogas composition. The organic content in the substrate is used as a kinetic parameter for biogas production using the modified Gompertz, Logistic, and Monod kinetic equation. The research results show that in mesophilic conditions, a recycling ratio of 25 % shows better results compared to ratios of 0 and 15 % where biogas production is 20×10-5 L/mgVS.day, with a best composition of methane, carbon dioxide and hydrogen sulfide each of 88.2; 10.8; and 0.07 % (v/v), with ΔVS decomposition at 15 % and 25 % recycle ratio of 42.50 and 45.83 % (w/v). The equation for the biogas production rate constant as a function of temperature obtained is the biogas production rate constant: M=299.81+exp(14.28299.8(0.39−t)+2) for logistic model, M=27.2xs2.46+s for monod model, M=250.1×exp{−exp[1.85.e250.1(0.42−t)+1]} for Gompertz modified kinetic model. Based on the scanning electron microscope results, it can be seen that the membrane used is an ultrafiltration membrane type, with a characteristic thickness of 7-8 µm and a pore size of 100–300 nm. The scanning electron microscope results also show that effluent contaminants deposition in the inner layer (spinger membrane) and deformation of the spinger structure are driven by forces during the effluent recycling process. The results obtained in this research show that this condition provides a clean, effective, and low-energy biogas production system that can be optimistically applied to the national palm oil industry power generation system.

Sustainable Alkali Activation: The Role of Water- and Alkali-Treated Sisal Leaf Wastewaters in Solid- Waste-Based Composite Synthesis.

The intricate composition of wastewater impedes the recycling of agricultural and industrial effluents. This study aims to investigate the potential of sisal leaf wastewater (SLW), both water-treated (WTSLW) and alkali-treated (ATSLW), as a substitute for the alkali activator (NaOH solution) in the production of slag-powder- and fly-ash-based composites, with a focus on the effects of WTSLW substitution ratios and sisal leaf soaking durations. Initially, the fresh properties were assessed including electrical conductivity and fluidity. A further analysis was conducted on the influence of both WTSLW and ATSLW on drying shrinkage, density, and mechanical strength, including flexural and compressive measures. Microstructural features were characterized using SEM and CT imaging, while XRD patterns and FTIR spectra were employed to dissect the influence of WTSLW substitution on the composite's products. The results show that incorporating 14 wt% WTSLW into the composite enhances 90-day flexural and compressive strengths by 34.8% and 13.2%, respectively, while WTSLW curtails drying shrinkage. Conversely, ATSLW increases porosity and decreases density. Organic constituents in both WTSLW and ATSLW encapsulated in the alkaline matrix fail to modify the composites' chemical composition. These outcomes underscore the potential for sustainable construction materials through the integrated recycling of plant wastewater and solid by-products.

A Critical Review of Systems for Bioremediation of Tannery Effluent with a Focus on Nitrogenous and Sulfurous Species Removal and Resource Recovery

Tanneries generate copious amounts of potentially toxic sludge and effluent from the processing of skins and hides to leather. The effluent requires remediation before discharge to protect the receiving environment. A range of physicochemical methods are used for pre- and post-treatment, but biological secondary remediation remains the most popular choice for the reduction of the organic and macronutrient fraction of tannery effluent. This review provides an update and critical discussion of biological systems used to remediate tannery effluent. While the conventional activated sludge process and similar technologies are widely used by tanneries, they have inherent problems related to poor sludge settling, low removal efficiencies, and high energy requirements. Treatment wetlands are recommended for the passive polishing step of beamhouse effluent. Hybrid systems that incorporate anoxic and/or anaerobic zones with sludge and/or effluent recycling have been shown to be effective for the removal of organics and nitrogenous species at laboratory scale, and some have been piloted. Novel systems have also been proposed for the removal and recovery of elemental sulfur and/or energy and/or process water in support of a circular economy. Full-scale studies showing successful long-term operation of such systems are now required to convince tanneries to modernize and invest in new infrastructure.

Iron-based mixotrophic denitrification for enhancing nitrate removal from municipal secondary effluent: Performance, microbial community dynamics, and economic feasibility

High nitrate content limits the recycling of the secondary effluent of wastewater treatment plants. In the research, one biomass-iron mixture (BIM) filter material based on mixotrophic denitrification mode (heterotrophic and iron-driven autotrophic denitrification) was developed and used to construct a novel denitrification biological filter (BIM-DNBF) for the nitrogen removal of secondary effluent. BIM-DNBF had a short start-up time (approximately 9 days), and high total nitrogen removal (81 %-89 %) without external addition of organic carbon sources during the whole operation. The coexistence of dominant heterotrophic-denitrification-like Pseudomonas and Erysipelothrix as well as iron-driven autotrophic-denitrification-like Citrobacter, Acidovorax, etc. were found in the BIM-DNBF. Moreover, biomass was recognized as one key player in promoting the reduction of Fe3+ to Fe2+, thereby facilitating the occurrence of iron-driven autotrophic denitrification. In addition, BIM-DNBF was assessed to be affordable. These findings provide evidence that BIM-DNBF can be an efficient technology for nitrogen removal of secondary effluent.

Myco-remediation of synthetic dyes: a comprehensive review on contaminant alleviation mechanism, kinetic study and toxicity analysis

AbstractA strong economic foundation can be achieved by the growth of a number of businesses, including food, paper, clothes, leather, and textiles. However, because of improper waste management, industrialization and modernization have resulted in the massive disposal of water effluent laden with harmful substances like dyes and heavy metals, which has negatively impacted the ecosystem. A new green technology called myco-remediation has emerged to battle harmful toxins while promoting sustainable development effectively and economically. This review employed enzymatic degradation, biosorption, and their influencing parameters for optimization in order to highlight the invaluable potential of fungal bioremediation for dye degradation. Current perspectives on enzyme immobilization techniques and kinetic studies of dye removal have been reviewed, which can aid in the selection of quick and effective removal processes. This research offers new insight into a criterion that is often overlooked in favor of dye decolorization efficiency: the toxicity assessment of pure dye and post-process metabolites produced following myco-remediation. Our attention has been directed towards toxicity analysis at many levels, including genotoxicity, phytotoxicity, and zoo-toxicity. This is important to keep in mind when considering the extensive implications of myco-remediation for the recycling and reuse of industrial effluent. Enzyme engineering and omics technologies have been highlighted as potential future developments.

Unlocking concrete strength: Empowering sustainable practices through effluent recycling in casting and curing

This research explores the viability of employing effluent, a by product of sewage treatment plants (STPs), as an alternative resource for casting and curing concrete, with the aim of mitigating the consumption of potable water. Seven distinct combinations were formulated to cast and cure M20 grade concrete using both potable water and effluent. Effluent samples from STPs underwent rigorous testing to assess their compliance with Indian standards (IS). Subsequently, 42 concrete cubes were cast using these water sources and subjected to compressive strength testing. The study unveiled that the “PWE2″ combination, characterized by potable water for casting and effluent for curing, yielded the highest compressive strength at 34.79 MPa. The use of portable water for casting and effluent for curing leads to increase in C-S-H gel by 5.46 % contributing to increase compressive strength observed in XRD test. These findings underscore the potential of effluent reuse as a sustainable practice in the concrete industry, with environmental and economic benefits.

Greenhouse gas production from an intermittently dosed cold-climate wastewater treatment wetland

This study explores the greenhouse gas (GHG) fluxes of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) from a two-stage, cold-climate vertical-flow treatment wetland (TW) treating ski area wastewater at 3 °C average water temperature. The system is designed like a modified Ludzack-Ettinger process with the first stage a partially saturated, denitrifying TW followed by an unsaturated nitrifying TW and recycle of nitrified effluent. An intermittent wastewater dosing scheme was established for both stages, with alternating carbon-rich wastewater and nitrate-rich recycle to the first stage. The system has demonstrated effective chemical oxygen demand (COD) and total inorganic nitrogen (TIN) removal in high-strength wastewater over seven years of winter operation. Following two closed-loop, intensive GHG winter sampling campaigns at the TW, the magnitude of N2O flux was 2.2 times higher for denitrification than nitrification. CH4 and N2O emissions were strongly correlated with hydraulic loading, whereas CO2 was correlated with surface temperature. GHG fluxes from each stage were related to both microbial activity and off-gassing of dissolved species during wastewater dosing, thus the time of sampling relative to dosing strongly influenced observed fluxes. These results suggest that estimates of GHG fluxes from TWs may be biased if mass transfer and mechanisms of wastewater application are not considered. Emission factors for N2O and CH4 were 0.27 % as kg-N2O-N/kg-TINremoved and 0.04 % kg-CH4-C/kg-CODremoved, respectively. The system had observed seasonal emissions of 600.5 kg CO2 equivalent of GHGs estimated over 130-days of operation. These results indicate a need for wastewater treatment processes to mitigate GHGs.

Removal of Heavy Metals from Contaminated Aquatic Streams Using a Resin Supported Green nZVI

This study addresses the escalating demand for clean water resources driven by population growth and water quality deterioration. The research focuses on evaluating the efficacy of a nanocomposite material, incorporating zero valent iron nanoparticles into a chelating cation exchange resin matrix, for selectively removing heavy metals from polluted aquatic environments. The selected resin, featuring iminodiacetic acid functional groups, demonstrates notable selectivity for heavy metal cations over alkali earth metals. Column experiments were conducted to assess the nanocomposite’s performance, utilizing a feed solution spiked with heavy metals at concentrations ten times higher than Greek legislation limits for wastewater effluent recycling. The nanocomposite exhibited significant effectiveness for Cu, Cr(VI), and Pb, consistently maintaining Cu levels below detection limits and demonstrating limited breakthrough of Cr(VI) and Pb depending on experimental conditions. However, the removal efficiency was lower for Ni and insufficient for Cd, Zn, and As in this complex multicomponent solution. This research contributes valuable insights into the potential application of the developed nanocomposite for targeted removal of specific heavy metals in contaminated water sources, providing a foundation for further exploration and application in water remediation technologies.

Groundwater conservation, and recycling and reuse of textile wastewater in a denim industry of Bangladesh

Bangladesh holds the 2nd position after China in the global apparel market in terms of denim export. In the textile industry clusters of Bangladesh, the groundwater level is depleting at an alarming rate due to overconsumption and mismanagement. The present study evaluates the groundwater conservation potential of a denim facility in Manikganj District through an effluent recycling and reuse approach. In this study, 100% treated wastewater and 10% treated wastewater mixed with softwater were utilized in the wet processing plant to dye and wash sample denim products and investigated for their fabric quality using seven parameters. The test results followed the requirements given by the North American and European fashion brands that source denim products from Bangladesh. The feasibility assessment of groundwater conservation through its high (100%) and low (10%) recycling rates indicated that the studied facility can potentially save around 619,230 m3 and 61,923 m3 of groundwater in a year, respectively.

A multi-criteria optimization and decision-making framework of green DME reactor configurations with a focus on high productivity and low CO2 emission rate

The combination of a conventional Dimethyl Ether (DME) reactor with hydrogen perm-selective membrane and effluent recycling creates innovative membrane reactor (MR) configurations that can efficiently improve thermodynamic limits plus low kinetic rates. In the present article, two eco-friendly configurations were applied to the DME conventional reactor (CR) to boost the DME production rate, yield, and selectivity. These configurations comprise two concentric pipes in which in the 1st configuration the fresh synthesis gas is fed to the inner tube side, hydrogen permeates through the reaction zone, and finally the effluent is recycled back to the outer tube, while in the 2nd one, the effluent of outer tube recycled to the inner pipe. The comprehensive 1-D heterogeneous model has an excellent agreement with industrial data. Also, the simulation results reveal that the higher temperature profile in the 2nd configuration is the consequence of more intensification in the reaction zone by H2 injection and proper heat removal which leads to around 9.5 %, 8.22 %, and 10 % increases in the DME production rate, selectivity, and yield compared to CR, respectively. Enjoying reaction output recycling and H2 permeation, the reaction rate of CO and CO2 hydrogenation plus methanol dehydration enhances significantly in the 2nd scheme.According to Euclidean Distance, the optimization results show that the MODE algorithm has a better performance compared to NSGA-II to obtain optimal Pareto Front and also more rapid respect to lower computational time. The LINMAP approach provides a minimum deviation index among all three decision-making algorithms. Employing optimal operation conditions leads to an enhancement of 17 %, 47 %, and 36 % in DME production rate, selectivity, and yield compared to CR. This eco-friendly configuration prevents the emission of 22000 tons of per year CO2 to the atmosphere.

Distinguishable Recycling and Photodegradation Processes of Real Industrial Effluents and Blue Dianix Dye in the Presence of Different TQDs Size

Three titanium dioxide quantum dots (TQDs) samples were successfully synthesized at low calcination temperatures via a modified precipitation method at T1 = 330, T2 = 360, and T3 = 400 °C. The synthesized TQDs samples were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the crystallinity, purity, and existence of asymmetric circle forms for the TQDs catalysts. Also, the surface area, band gap energy, and crystallite size at different calcination temperatures are 322.32 m2/g, 3.20 eV, and 4.9 nm at 300 °C, 292.39 m2/g, 3.14 eV, and 5.4 nm at 360 °C, and 254.66 m2/g, 3.07 eV, and 6.2 nm at 400 °C, respectively. A xenon photoreactor (70 W/cm2) was used to evaluate the photodegradation process of Blue Dianix dye and sunlight for real industrial effluent treatment. The photocatalytic activity decreases as the crystallite size increases in the TQD samples. Photocatalytic activity of TQDs due to their distinguishable crystalline domain size of less than 10 nm and their high surface area. The photodegradation rate of real industrial effluents was evaluated according to the COD limits permitted by Egyptian environmental law. Also, TOC and COD analyses evaluated 12 recycled samples of TQDs.

Statistical analysis of the physico-chemical characteristics of industrial effluents: Case of evaporating basins used as final storage for effluent

Evaporating basins are common storage for industrial effluent in most renewable power plants. Various types of research on the environmental consequences and issues of this experience have suggested this method of disposal to prevent industrial effluents withdrawal into the ocean, and dams and prevent water contamination.Nevertheless, this approach may have significant worldwide environmental implications. Focusing on dedicated research methods for a power plant in the south of Morocco that employed evaporating basins for storing its effluent, we evaluated the development of the effluent's Physico-chemical characteristics over a timeframe of one year.The evaporation basins undergo thorough assessment to evaluate the effects of industrial effluents, leading to the observation of a significant increase in the physicochemical characteristics of the discharged effluents, mainly EC, BOD5, Na, and Cl2. This rise in water contamination can be attributed to the aforementioned factors. Statistical analysis, specifically correlation and regression, was employed to examine the coefficients of the primary physicochemical properties. The objective was to determine the effluent characteristics that exhibited strong associations and close relationships.The primary goal of this study is to highlight the drawbacks associated with storing wastewater in evaporation ponds, a common practice among many industrial companies. It is crucial to consider that these ponds attract a diverse range of bird and animal species, and any contamination of the water can pose significant environmental and ecological risks in the event of an accidental leakage or spill, potentially harming wildlife. To mitigate these potential issues, it is recommended to explore alternatives such as industrial effluent reuse and recycling, which can help minimize the environmental and ecological impacts.

Comparative performance of subsurface and free-surface planted beds for polishing real recycled paper effluent: Influence of biomass ratio to pollutant

A polishing technology through phytoremediation was performed to reduce COD and colour from real recycled paper effluent using Typha angustifolia. Subsurface (SS) and free surface (FS) systems were operated, with batches of 10 and 26 L of effluent treated, respectively. Various numbers of plants (4 (T4), 6 (T6) and 8 (T8) plants with mass of 54, 82 and 100 g, respectively) were vegetated in each system. All treatments were run with plant control and control contaminants. After 60 days of treatment, there was significant (p < 0.05) removal of contaminants, with the highest removals of colour were 71 % (T8) and 80 % (T4); and the highest COD removals were 97 % (T8) and 89 % (T8) for SS and FS, respectively. Additionally, COD and colour removal for the treatment with eight plants (T8) in the SS system (97 % and 71 %, respectively) was significantly higher than for the treatment with four plants (T4) (COD removal = 91 % and colour removal = 50 %). This is due to the high survival percentages of plants in T8, with 100 % tolerance in the SS system which represents healthy plants undergoing the phytoremediation process with no or less fewer toxicity symptoms. Overall, the SS system performed better since the FS system faced a higher pollutant loading. The mass ratio of plants to COD for the SS system with eight plants is 37 which means for every 1 g of COD, about 37 g of plants is required to facilitate the phytoremediation process with high removal efficiency and 100 % survival of plants.

Microbial approaches for pharmaceutical wastewater recycling and management for sustainable development: A multicomponent approach

A microbial-driven approach for effluent treatment, recycling, and management of Pharmaceutical and Personal Care Products (PPCPs) has been undertaken to mitigate the menace of water contamination. Bioremediation processes are mainly considered the first preference in pharmaceutical wastewater recycling and management. PPCPs are reported as one of the primary sources of emerging contaminants in various water matrices, which raises concern and requires efficient management. Their widespread utilization, persistently high level, and resistance to breaking down make them one of the potentially dangerous compounds causing harm to the ecosystem. Continually increasing PPCPs level PPCPs contaminants in water bodies raised concern for human health as they can produce potential risks with harmful and untoward impacts on our health. PPCPs are composed of multiple diverse compounds used by humans and animals, which include biopharmaceuticals, vitamins and nutritional supplements, antibiotics, counter-prescription drugs, cosmetics products, and unused pharmaceutical products. Personal care products are found to be bioaccumulative, reduce water quality and potentially impact ecological health. However, continual exposure to PPCPs in aquatic organisms, impacts their endocrine function disruption, gene toxicity, and antibiotic resistance. Decreased water quality may result in an outbreak of various water-borne diseases, which could have acute or long-term health complications and may result in an outbreak of various water-borne diseases, which could have acute or long-term effects on public and community health. Polluted water consumption by humans and animals produces serious health hazards and increased susceptibility to water-borne diseases such as carcinogenic organic or inorganic contaminants and infectious pathogens present in water bodies. Many water resource recovery facilities working on various conventional and advanced methods involve the utilization of microbes for filtration and advanced oxidation processes. Therefore, there is an immense need for bioremediation techniques facilitated by mixed cultures of bacteria, algae, and other microbes that can be used as an alternative approach for removing pharmaceutical content from effluent. This review highlights the various sources of PPCPs and their impacts on soil and water bodies, resulting in bioaccumulation. Different techniques are utilized to detect PPCPs, and various control strategies imply controlling, recycling, and managing waste.

Assessment of Effluent Recycling Process and Drilling Waste Management Procedure in Some Niger Delta States

The assessment of effluent recycling process and drilling waste management procedure in some Niger Delta States in Nigeria to identify ways to minimize cost in oil production, have been investigated. Niger Delta States are located in southern part of Nigeria, which are known to be the highest in crude oil production in Nigeria, however, the process of exploration and extracting of the oil also affects the ecosystem of that particular area. A comparative design was taken, which analysed various indices in the conventional methods of drilling waste management applied in a site in Edo State northern part of Nigeria, and comparing it to some modified methods employed in the wellhole locations in Imo State. The research was conducted in a wellhole site located in Ohaji Imo state, southern part of Nigeria, afterward, a correlation was drawn between the volume of generated waste and the drilling waste management, in order to develop a cost-effective model of waste management in the region. From the result obtained from the quantitative measures taken at the four drilling sites in Edo and Imo States, a significant reduction in waste volume of about 50% was observed, which therefore minimized the cost of drilling observed in Ohaji site, maybe as a result of the enhanced drilling design layouts using the effluent recycling method adopted in that location. The study therefore recommends the adoption of effluent recycling as a technique to be incorporated in the management of drilling waste during onshore petroleum development in the Niger Delta, among others, which would improve productivity.

Maximization of Energy Recovery from Starch Processing Wastewater by Thermophilic Dark Fermentation Coupled with Microbial fuel Cell Technology

Utilization of organic wastewater for hydrogen production has dual advantages of clean energy generation and bioremediation, which is sustainable for a longer period. To maximize the energy recovery from starch rich wastewater, a two stage system comprising of thermophilic dark fermentation coupled with microbial fuel cell was employed. A single parameter optimization strategy was implemented for the operation of the batch system. The maximum cumulative hydrogen production obtained was 2.56 L L−1 with a 48% reduction in COD under the optimal conditions of 35 g L−1 initial substrate concentration (COD), temperature 60 °C, and pH 6.5. The H2 yield and H2 production rate were 6.8 mol H2/kg CODreduced and 731.3 mL L−1 h−1, respectively. The effect of the organic loading rate (OLR) on H2 production rate was studied in a continuous stirred tank reactor (CSTR). A maximum hydrogen production rate of 913 mL L−1 h−1 was observed at an OLR of 5.6 g L−1 h−1. Effluent recycle played an important role in the improvement of H2 production. A maximum H2 production rate of 1224 mL L−1 h−1 was observed at a recycle ratio of 0.6. Power density of 4.2 W m−3 was observed with MFC using the dark fermentative spent media neutralized with carbonate buffer at an optimal pH of 7. A total COD reduction of 86% was observed.

Treatment performance of multistage active biological process (MSABP) reactor for saline sauerkraut wastewater: acclimatization, optimization and improvement.

The wastewater with a high concentration of organics and salt is a major contaminant in the production of sauerkraut. In this study, a multistage active biological process (MSABP) system was constructed to treat sauerkraut wastewater. The key process parameters of the MSABP system were analyzed and optimized by response surface methodology. The optimization results indicated that the most optimal removal efficiencies and removal loading rates of chemical oxygen demand (COD) and NH4+-N were 87.9%, 95.5%, 2.11kg·m-3·d-1 and 0.12kg·m-3·d-1, respectively, with hydraulic retention time (HRT) of 2.5 d and pH of 7.3. Meanwhile, this system could also be improved for the further treatment of COD and total nitrogen by effluent recycle and ozone oxidation. The COD and total nitrogen removal efficiencies of the modified MSABP system were 99.9% and 60.2%, respectively. In addition, the modified system could also reduce the potential harm from high concentrations of NO2--N.

Integrated poultry waste management by co-digestion with perennial grass: Effects of mixing ratio, pretreatments, reaction temperature, and effluent recycle on biomethanation yield

This work aims to enhance the efficiency of integrated poultry waste management in bio-circular-green economy by maximizing the co-digestion of chicken manure and its digestate-grown biomass. In a series of batch assays, Napier grass (NG) was mixed with chicken manure (CM) at various proportions (100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100) to identify co-substrate synergism, followed by physiochemical conditioning (size reduction and ultrasonication) of NG before co-digestion. Results indicated that NG mix of at least 80% was required to gain a full methanation potential of the individual substrates; no synergistic ratio above unity was found. However, the combined effect of size reduction and sonication was found to markedly improve the co-substrate’s biodegradability by 88.7%. The findings were then used to run continuous co-digestion at various operating regimes. In optimal continuous co-digestion condition, NG particle size of 0.6–2.4 mm combined with sonication intensity at 1111 kJ/kgTS improved biomethanation yield as high as 106.3%. Sub-thermophilic digestion at 45 °C was shown to give a higher and more stable CH4 yield than at 55 °C. Finally, it was also found that recycling liquid effluent at 40% to replace freshwater in feed, although showed no significant difference in CH4 yield (α = 0.05), noticeably increased system buffer capacity. This optimized biodegradation regime could give co-digestion waste management a higher overall plant efficiency and economic return.