Upflow Anaerobic Sludge Blanket Research Articles

Exploration of Microalgae-Activated Sludge Growth Performance in Lab-Scale Photobioreactors under Outdoor Environmental Conditions for Wastewater Biotreatment

Increasing the volume of untreated and inadequately treated municipal wastewater undermines the circular economy potential of wastewater resources, particularly in low-income regions. This present study focused on and evaluated the performance of native microalgae-activated sludge (MAS) growth for tertiary treatment of anaerobically digested wastewater from an up-flow anaerobic sludge blanket (UASB) in an outdoor lab-scale photobioreactor (2.2 L). Three conditions with distinct MAS inoculum concentrations alongside three controls were operated in batch mode for 5 days hydraulic retention time (HRT) at 11.5:12.5 photo-hours. The MAS inoculum concentration influenced the treatment outcome. The best performance was observed when the MAS concentration was 0.10/0.20 g L−1, and the cell density was 1.60 × 107 cells mL−1, total biomass productivity of 0.10 g TSS L−1 d−1, total phosphorus uptake of 85.1%, and total nitrogen uptake of 66.1%. Logarithmic removal (Log-Re) of bacterial pathogens (water quality indicators) showed Log-Re 3.4 for total coliforms (1.37 × 102 CFU 100 mL−1) and 4.7 for Escherichia coli (0.00 × 100 CFU 100 mL−1). The results revealed optimum remediation performance and nutrient recovery potential with appropriate inoculum concentration, in admiration to advancing the science of circular economy.

Domestic and industrial wastewater generation and its energy recovery potential in Bangladesh

A sizable amount of wastewater is produced every day. Wastewater treatment is required to safeguard the environment, human health, flora, and aquatic life. However, wastewater treatment is an expensive operation on one hand, but on the other hand, wastewater contains five to ten times the energy needed for treatment in the form of chemical energy. This energy is accessible via biological processes. Wastewater contains potential and kinetic energy in addition to chemical energy, and it can be harnessed to generate hydropower. Any country must have a central inventory of wastewater in order to harvest this energy. To harness renewable energy from wastewater sector, it is necessary to have a central database for wastewater generation with type of wastewater and its parameters. Unfortunately, Bangladesh lacks a reliable inventory of national wastewater generation, composition, and attributes that may be utilized for estimating wastewater's potential energy output. Therefore, the aim of this research is to estimate the annual total domestic and industrial wastewater output in Bangladesh and estimate its energy recovery potentials. To estimate domestic wastewater (DWW) and industrial wastewater (IWW), an income-based estimating technique and industry-based reports/literature, respectively have been used. Few novel technologies, such as up-flow anaerobic sludge blankets (UASB), anaerobic digestion (AD), and micro hydropower plants (MHP), and five scenarios using only half of the total wastewater (DWW & IWW) have been considered for estimating the energy recovery potential of wastewater. For the hydropower evaluation using MHP, the unit total head is assumed, whereas the average chemical oxygen demand (COD) has been considered for the energy potential assessment of the UASB and AD. Techno-economic analysis (TEA) steps have been also discussed. Results indicate that the expected annual output of DWW and IWW is 4874 million m3 /yr. and 452 million m3 /yr., respectively. In terms of energy potential, scenario 2 has the highest (1986 Giga watt-hour equivalent (GWh)/yr.)), followed by scenario 1 (1857 GWh/yr.), scenario 5 (1770 GWh/yr.), scenario 3 (1401 GWh/yr.), and scenario 4 (976 GWh/yr.). This rigorous research will open up new horizons by attracting the attention not only of Bangladeshi researchers, but also of the international community.

Role of sulfate in regulating performance and metabolic mechanisms of bioelectrochemical up-flow anaerobic sludge blanket fed with methanolic wastewater

To investigate the impact of sulfate (SO42−) on the performance of bioelectrochemical up-flow anaerobic sludge blanket (BE-UASB), the COD/SO42− ratio of sulfate-containing methanolic wastewater was gradually decreased from 20 to 3. The results showed that BE-UASB maintained higher COD and SO42− removal (i.e., 91% and 70%, respectively) with methane production rate of 278.7 mL/Lreactor/d at COD/SO42− ratio from 10 to 5, ensuring efficient energy recovery. Sulfidogenesis enabled the sludge re-granulation while bioelectrocatalysis further contributed to the growth/proliferation of biomass with interwoven filaments, rods, and spherical microorganisms. 16 S rRNA gene analysis demonstrated that bioelectrocatalysis promoted the diversity of methane-producing archaea (MPA), including Methanomethylovorans, Methanosaeta, Candidatus_Methanofastidiosum, and Methanobacterium. Sulfate-reducing bacteria (SRB), mainly comprising G_norank_f_Syntrophobacteraceae, Desulfomonile, and Syntrophobacter, tended to be enriched on bioelectrodes, which not only eased the competition with MPA but also achieved simultaneous removal of COD and SO42− in synergy with MPA.

Enhancing Anaerobic Digestion with an UASB Reactor of the Winery Wastewater for Producing Volatile Fatty Acid Effluent Enriched in Caproic Acid

The production of Volatile Fatty Acids (VFAs) from wastewater holds significant importance in the context of biorefinery concepts due to their potential as valuable precursors for various bio-based processes. Therefore, the primary objective of this research is to investigate the fermentation of Winery Wastewater (WW) in an Upflow Anaerobic Sludge Blanket (UASB) reactor to generate VFAs, with particular emphasis on Caproic Acid (HCa) production and the dynamics of the microbiota, under varying Hydraulic Retention Time (HRT) periods (8, 5, and 2.5 h). The change from an 8 h to a 5 h HRT period resulted in an approximately 20% increase in total VFA production. However, when the HRT was further reduced to 2.5 h, total VFA production decreased by approximately 50%. Concerning the specific production of HCa, expressed in grams of Chemical Oxygen Demand (gCOD), the maximum yield was observed at around 0.9 gCOD/L for a 5-h HRT. Microbial population analysis revealed that Eubacteria outnumbered Archaea across all HRTs. Population dynamics analysis indicated that the Firmicutes Phylum was predominant in all cases. Within this phylum, bacteria such as Clostridium kluyveri and Clostridium sp., known for their ability to produce HCa, were identified. Based on the results obtained, the application of the UASB reactor for WW treatment, within the biorefinery framework, has the potential to provide a practical alternative for HCa production when operated with a 5 h HRT.

Sewage treatment in cities of the state of Minas Gerais, Brazil, that use the UASB reactor as the only biological treatment: A case study

This article analyzed the performance of four Wastewater Treatment Plants (WWTP) in three cities in the state of Minas Gerais, Brazil, which use the UASB (Upflow Anaerobic Sludge Blanket) reactor as the only stage of biological treatment. When evaluating the characteristics of treated wastewater, it was verified that the WWTPs were not efficient enough to meet the disposal standards established by environmental agencies. Most of the sewage samples from Ipatinga municipality did not meet the minimum removal for BOD5 of 60 % and COD of 55 %, being 56 % and 46 % the average removals, respectively. These results suggest the need for improvements in the current biological treatment and/or the adoption of a polishing step. The raw sewage had high biodegradability (BOD5/COD>0.4) and the UASB reactors reduced this biodegradability (ranging from 0.2 to 0.43) by removing the content of easier degradation. A strong linear correlation (R2 = 0.85) was observed between COD and DBO5 data for the raw sewage from Timóteo municipality, making it possible to estimate the second parameter as a function of the first. When compared with wastewater characterized and used in fertigation studies, the treated sewage samples of the present study show potential for application in agricultural practices.

Performance of Microbial fuel cell as a post treatment unit of UASB reactor for distillery spent wash

Post treatment of Up-flow anaerobic sludge blanket reactor (UASBR) effluents by a duel chambered Microbial fuel cell (MFC) was evaluated for high strength distillery spent wash. Bench scale UASBR (5 L capacity) and MFC (1 L capacity) with carbon electrodes having proton exchange membrane were used to elucidate the energy generation potential and substrate (COD) removal efficiency. Step by step, the influent COD concentration of UASB-MFC unit was increased. The MFC shows increasing trend of open circuit voltage, COD removal and substrate degradation rate with increase in influent COD concentration. The maximum COD removal (73.79%) and open circuit voltage (1.1 V) were achieved at 20600 mg/L of COD. At maximum COD concentration, MFC showed power density (maximum), substrate degradation rate and power yield as 61.61mW/m2, 1.086 kg COD/m3day and 0.041 W/kg CODR respectively. UASB-MFC combined unit gave maximum COD removal of 90%. The experimental data revealed the potential of MFC as feasible, economic (cost saving) and sustainable option.

Bacterial community composition in a two-stage anaerobic membrane bioreactor for co-digestion of food waste and food court wastewater

This study investigated the microbial community of a two-stage anaerobic membrane bioreactor (2S-AnMBR) co-digesting food waste and food court wastewater. The hydrolysis reactor (HR) was dominated by Bacteroidetes and Firmicutes phylum, with genus Lactobacillus enriched due to food waste fermentation. The up-flow anaerobic sludge blanket (UASB) was dominated by genus such as Methanobacterium and Methanosaeta. The presence of Methanobacterium (91 %) and Methanosaeta (7.5 %) suggested that methane production pathways inevitably undergo both hydrogenotrophic and acetoclastic methanogenesis. Hydrogen generated during hydrolysis fermentation in the HR contributed to methane production in the UASB via hydrogenotrophic pathways. However, the low abundance of Methanosaeta in the UASB can be attributed to the limited inffluent of volatile fatty acids (VFA) and the competitive presence of acetate-consuming bacteria Acinetobacter. The UASB exhibited more excellent dispersion and diversity of metabolic pathways compared to the HR, indicating efficient methane production.

Bio-CH4 yield of swine manure and food waste optimized by co-substrate proportions diluted in domestic sewage and pH interactions using the response surface approach

This research aimed at evaluating optimal conditions to obtain value-added metabolites, such as bio-CH4, by co-digesting swine manure and food waste diluted in domestic sewage. The assays were carried out in batches using the statistical methods of Rotational Central Composite Design (RCCD) and Surface Response to evaluate the ranges of food waste (1.30–9.70 gTS.L−1), pH (6.16–7.84) and granular Upflow Anaerobic Sludge Blanket sludge as inoculum (2.32–5.68 gTS.L−1), besides about 250 mL of swine manure in 500 mL Duran flasks. According to the RCCD matrix, bio-CH4 yields among 600.6 ± 60.1 and 2790.0 ± 112.0 mL CH4 gTS.L−1 were observed, besides the maximum CH4 production rate between 0.4 ± 0.5 and 49.7 ± 2.0 mL CH4 h−1 and λ between ≤0.0 and 299.3 ± 4.5 h. In the validation assay, the optimal conditions of 9.98 gTS.L−1 of food waste, pH adjusted to 8.0 and 2.20 gTS.L−1 of inoculum were considered, and the bio-CH4 yield obtained (5640.79 ± 242.98 mL CH4 gTS.L−1 or also 5201.83 ± 224.07 mL CH4 gTVS.L−1) was 11.3 times higher than in assays before optimization (499.3 ± 16.0 mL CH4 gTS.L−1) with 5 gTS.L−1 of food waste, 3 gTS.L−1 of inoculum and pH 7.0. Besides, the results observed about the energetic balance of the control and validation assays highlight the importance of process optimization, as this condition was the only one with energy supply higher than the energy required for its operation, exceeding max consumption sevenfold. Based on the most dominant microorganisms (Methanosaeta, 31.06%) and the metabolic inference of the validation assay, it could be inferred that the acetoclastic methanogenesis was the predominant pathway to CH4 production.

Corn ethanol production with thin stillage anaerobic digestion for bioenergy recovery: A technical and economic evaluation

The generation of bioenergy from thin stillage in a corn ethanol mill provides a new perspective for the use of by-products in a circular economy concept. Alternative technological routes for the corn ethanol by-products energy and nutrients recovery must be investigated to assess present and future decision-making toward economic and environmental indicators. The theoretical biogas production from an up-flow anaerobic sludge blanket (UASB) reactor in a corn-ethanol mill and the potential thermal and electrical power generation along with the avoided greenhouse gas (GHG) emissions were estimated for a large-scale industrial facility. This work aimed to assess the anaerobic digestion (AD) contribution to techno-economic indicators of a corn ethanol mill in three scenarios: 1) Standard corn-to-ethanol mill; 2) AD-CHP - thin stillage AD to produce biogas and its burning in a combined heat and power (CHP) system; 3) AD-BU - biogas purification to obtain and commercialize biomethane. The existent Brazilian market and fuels and biofuel policies place the system without AD in a slightly better position when analyzing financial indicators related to investment return. In contrast, the global energy and mass balances considering thin stillage AD showed that in the AD-CHP scenario, processing 1 ton of thin stillage would produce 10.37 m³ of biogas, which could generate 119.9 MJ of heat and 24.7 kWh of electricity in a CHP system, favoring a greener energy scenario. The energy recovered from biogas returns to the industry, supplying 7.15% of the heat required for steam production and 52.74% of the electricity requirement for industrial processing. As a renewable energy source, biogas would replace fossil sources for energy generation avoiding GHG emissions. Extrapolating the results of the present work to the Brazilian national scale, the biogas yield from the corn-to-ethanol industry would be 179.68 million m³ , the thermal energy generation from biogas could mitigate 125,574.42 ton CO2eq, and the electricity replacement could mitigate 58,193.02 ton CO2eq. Besides the mentioned energy generation and environmental benefits, the financial indicators for the examined scenarios showed that the Brazilian market and public policies related to biogas/biomethane are constraints to overcoming to larger adoption of AD by the corn-to-ethanol industry.

Dissolved organic matter composition and microbial community dynamics in two-phase multi-staged up-flow anaerobic sludge blanket treatment of tapioca starch processing wastewater

The molecular changes in complex dissolved organic matter and the microbial community structure in a laboratory-scale two-phase multi-staged up-flow anaerobic sludge blanket (MS-UASB) system were determined by unknown screening analysis with Orbitrap mass spectrometry and next-generation sequencing using the Illumina® Miseq platform. The acidification (AC) reactor selectively decomposed less oxidized molecules and produced more oxidized compounds with less alkylated groups (lower number of CH2 groups). Subsequently, the MS-UASB removed a wide range of CHO moieties and effectively biodegraded the compounds produced by the AC reactor. However, longer CH2-chain compounds were observed. The retained sludge obtained from the MS-UASB reactor under different operating conditions revealed the dominance of the genus Methanosaeta (an acetoclastic methanogen) in the archaeal community. In addition, the distribution of the microbial community structures of the retained sludge and floating sludge differed when the MS-UASB reactor was unstable.

Distillery Plant Upflow Anaerobic Sludge Blanket Reactor comparision of Energy regime in Mesophilic and Thermophilic conditions

In this study, comparison of energy regime analysis of mesophilic and thermophilic condition upflow anaerobic sludge blanket (UASB) reactor treating distillery effluent is studied. Percentage COD reduction in thermophilic condition was more by 6.96% than mesophilic condition due to which biogas production increased by 0.1 m3/kg COD removed. In thermophilic temperature condition, methenogenesis was more than acidification than in mesophilic temperature condition; effluent VFA concentration in mesophilic condition was more in thermophilic condition. Stability of thermophilic reactor was more than mesophilic reactor from VFA/ Alkalinity ratio. Waste water treatment plant consumes 2.10 kWh/m3 total energy which comprises of electrical, mechanical and manual energy in mesophilic temperature condition. Input given in the form of electrical energy was 2.07 kWh/m3 and energy recovered in the form of biogas was 185 kWh/m3. Total energy input in thermophilic temperature condition was 1.82 kWh/ m3 and biogas recovery was 211 kWh/m3 in the form of energy. Net saving in energy input was 0.28 kWh/m3 (12.98%) and biogas production increased by 25.9 kWh/m3 (14%) in the form of energy in thermophic temperature condition. Treatment of distillery wastewater in thermophilic temperature condition can be a good option as compared to mesophilic temperature conditions considering the aspect of energy and it seems feasible due to the availability of elevated temperature of the feed for UASB.

Internal driving mechanisms of microbial community and metabolism for granular activated carbon enhancing anaerobic digestion of high-strength sulfate organic wastewater

In this study, the feasibility of enhancing high-strength sulfate organic wastewater anaerobic digestion by adding granular activated carbon (GAC) and the internal driving mechanisms were investigated in up-flow anaerobic sludge blanket (UASB) reactors. The UASB reactor with GAC (GAC reactor) was more stable in COD removal efficiency and CH4 production than that without GAC (non-GAC reactor). When the influent COD concentration increased to 12,000 mg/L with a COD/SO42− ratio of 4.0, the COD removal efficiency and CH4 yield increased by 10.45 % and 20.50 %, respectively. Under inhibition condition with sulfides of 800 mg/L, specific methanogenic activity of GAC reactor sludge increased by 41.8 % compared to that of non-GAC reactor sludge. Electron transport system and microbial community results showed that GAC enhanced microbial activity and improved direct interspecies electron transfer (DIET) between potential electroactive microorganisms and Methanosaeta. Functional enzyme gene analysis demonstrated that GAC enhanced microbial metabolic activity, covering glycolysis, pyruvate metabolism, sulfate reduction, and methanogenesis. Therefore, the enrichment of key microorganisms, the promotion of DIET methanogenesis, and the improvement of functional metabolism activity may be the important reasons for GAC reactor sludge with higher methanogenic activity. Furthermore, synergistic promotion of sulfate-reducing metabolism and methanogenesis may be due to the establishment of potential syntrophic partnership between sulfate-reducing bacteria (Desulfovibrio) and Methanosaeta. This study deciphered internal driving mechanisms of microbial community and metabolism for GAC enhancing anaerobic digestion of high-strength sulfate organic wastewater.

Sustainable municipal wastewater treatment using an innovative integrated compact unit: microbial communities, parasite removal, and techno-economic analysis

BackgroundThe upflow anaerobic sludge blanket (UASB) reactors rely on bacterial communities to break down pollutants in wastewater (municipal or industrial).Methods and resultsIn this study, a novel combination of UASB followed by aerobic treatment has been proposed for the treatment of municipal wastewater focusing on bacterial communities using high-throughput sequencing and parasite removal in this novel combination of reactors. Moreover, economic estimation of the compact unit composed of two overlapping UASB reactors, followed by a downflow hanging non-woven fabric (DHNW) reactor, the anaerobic baffled reactor (ABR), and chlorine unit was investigated in this study based on community populations of 1000 and 10,000 inhabitants, with a municipal plant capacity of 54,000 and 540,000 m3/year. Cost estimation was conducted based on two scenarios, one considering the contingency cost and auxiliary facility, and the other excluding them. Non-metric multidimensional scaling (nMDS) revealed that the treatment stages structured the microbial communities. Proteobacteria was the most prevalent phylum in all treatment stages, followed by Bacteroidota in most stages. Firmicutes and Actinobacteria were also present in significant amounts. The treatment system achieved from 40 to 66.67% removal of parasites (parasitic nematode, Cryptosporidium, and microsporidia). Redundancy analysis (RDA) indicated a strong positive correlation between chemical and biological oxygen demand (COD/BOD) with Campylobacterales and could be used as a bioindicator of treatment performance.ConclusionThese findings can inform the development of more efficient and sustainable wastewater treatment systems that take into account microbial ecology and economic considerations.

Enhancing methane production and organic loading capacity from high solid-content wastewater in modified granular activated carbon (GAC)-amended up-flow anaerobic sludge blanket (UASB)

Anaerobic digestion of high solid-content wastewater is hindered by high organic loading rates (OLRs). Granular activated carbon (GAC) was reported to promote direct interspecies electron transfer (DIET) and enhance reactor performance. In this study, three up-flow anaerobic sludge blanket (UASB) reactors were supplied with GAC in different locations: bottom (R1), top (R2), and bottom+top (R3). The performances of three reactors at different OLRs treating high solid-content wastewater were evaluated. At a low OLR, the highest methane yield (74 ± 4 %, g CH4-COD/g TCOD) was detected when GAC was supplied at top of the UASB (R2). When a high OLR was applied, the UASB supplemented with GAC at both bottom and top (R3) achieved the highest methane yield (66 ± 2 %, g CH4-COD/g TCOD), whereas the UASB supplemented with GAC at the top (R2) failed. Further studies on spatial distributions of sludge stability, specific methanogenic activities (SMAs), and microbial communities demonstrated the different impacts of GAC location on reactor performance and sludge characteristics under different OLRs. This study highlights the significance of considering organic loading capacity treating high solid-content wastewater when choosing GAC-based UASB systems.

Acclimation of microbial communities to low and moderate salinities in anaerobic digestion

In recent years anaerobic digestion (AD) has been investigated as suitable biotechnology to treat wastewater at elevated salinities. However, when starting up AD reactors with inocula that are not adapted to salinity, low concentrations of sodium (Na+) in the influent can already cause disintegration of microbial aggregates and wash-out. This study investigated biomass acclimation to 5 g Na+/L of two different non-adapted inocula in two lab-scale hybrid expanded granular sludge bed (EGSB)-anaerobic filter (AF) reactors fed with synthetic wastewater. After an initial biomass disintegration, new aggregates were formed relatively fast (i.e., after 95 days of operation), indicating microbial community adaptation. The newly formed microbial aggregates accumulated Na+ at the expense of calcium (Ca2+), but this did not hamper biomass retention or process performance. The hybrid reactor configuration, including a pumice stone filter in the upper section, and the low up-flow velocities applied, were key features for retaining the biomass within the system. This reactor configuration can be easily applied and represents a low-cost alternative for acclimating biomass to saline effluents, even in existing digesters. When the acclimated biomass was transferred from EGSB to an up-flow anaerobic sludge blanket (UASB) reactor configuration also fed with saline synthetic wastewater, more dense aggregates in the form of granules were obtained. The performances of the UASB inoculated with the acclimated biomass were comparable to another reactor seeded with saline-adapted granular sludge from a full-scale plant. Regardless of the inoculum origin, a defined core microbiome of Bacteria (Thermovirga, Bacteroidetes vadinHA17, Blvii28 wastewater-sludge group, Mesotoga, and Synergistaceae) and Archaea (Methanosaeta and Methanobacterium) was detected, highlighting the importance of these microbial groups in developing halotolerance and maintaining AD process stability.

Synthetic vinasse treatment by combined UASB-ABR-AS system

Vinasse, or ethanol industry wastewater, is a major source of environmental pollution owing to its high levels of organic matter, toxic substances, and hard biodegradable compounds. Treatment of vinasse can reduce environmental pollutants significantly, and if well treated, it can be used as a fertilizer. This research aimed to evaluate the performance of a combined laboratory-scale system consisting of an upflow anaerobic sludge blanket (UASB) reactor and an anaerobic baffled reactor (ABR) followed by an activated sludge (AS) reactor in treating synthetic vinasse. The research was conducted for 208 days. The combined UASB-ABR-AS system was fed by synthetic vinasse under organic loading rate (OLR) between 2.5 and 13.5 kgCOD/m3.day. The COD removal efficiency rates of UASB, ABR, and AS units were obtained at 84%, 77.1%, and 90.7%, respectively. The overall COD removal efficiency rates of the combined UASB-ABR-AS system and methane production were 99.6% and nearly 72% (613.71 L/kgCOD), respectively. These results indicated that using the combined UASB-ABR-AS system is suitable for synthetic vinasse treatment and improves the effluent quality according to environmental standards.

Optimization of a combined system of vertical flow constructed wetland and solar photo-Fenton for ketoprofen removal in sewage and landfill leachate

Emerging contaminants in the environment are a matter of concern due to their widespread use and continuous disposal without proper treatment. Conventional treatments in sewage treatment plants (STPs) are not able to completely eliminate them, resulting in the presence of these compounds in several environmental matrices. Therefore, exploring and adding technologies to reduce or avoid the disposal of these compounds in the environment is necessary. This study aimed to use the solar photo-Fenton process combined with a partially saturated bottom vertical flow constructed wetland (VFCW) to remove ketoprofen (KET) from anaerobic effluent (sewage + landfill leachate) post-treated by a real-scale upflow anaerobic sludge blanket (UASB) reactor. The combined constructed wetland + solar photo-Fenton in pH 3.0 (CW + SPF3) and constructed wetland + solar photo-Fenton in pH 6.0 (CW + SPF6) systems showed high efficiency in degrading KET, achieving removal rates of 97% and 95%, respectively. The systems also showed efficiency in removing conventional parameters such as COD, BOD5,20, and turbidity. In addition to having a lower cost, only the combined CW + SPF6 system was able to eliminate toxicity for Artemia sp. and Lactuca sativa (TU < 0.4). The solar photo-Fenton process and constructed wetlands have proven to be compatible technologies. This combination resulted in an innovative and effective method for wastewater treatment systems containing emerging contaminants. The use of new technological arrangements for the treatment of sewage and effluents, such as constructed wetlands (CWs), which are nature-based solutions, and environmentally sustainable advanced solar oxidation processes, establish a NEXUS concept, promoting the circular economy.

Efficacies of a locust bean gum polymer on the startup of a novel upflow anaerobic sludge blanket reactor treating municipal sewage.

The present study investigates the potential of locust bean gum (LBG), in accelerating the startup of a novel upflow anaerobic sludge blanket (UASB) reactor handling municipal sewage. Under identical conditions, two lab-scale UASB reactors were operated in parallel, to substantiate this idea. The novel reactor (RH) with an inner centric hybrid UASB module and an outer concentric downflow hanging sponge (DHS) unit started off with an LBG polymer as an additive. Its performance was compared with a conventional system (RC). RH outclassed with an accelerated startup in 40 days, with the highest COD removal of 89% by the UASB compartment and 95% by the entire system (UASB + DHS). RC took nearly 85 days to achieve the highest COD removal of 83%. The polymer also succeeded with a dense sludge bed fastening most of the anaerobes, read by the least sludge volume index (SVI) of 26 mL/g. Specific methanogenic activity (SMA) (RH - 0.715 ± 0.05 and RC - 0.670 ± 0.07 g CH4-COD/g VSS/ day) and extracellular polymer (ECP) concentration (0.30-0.32 g/g VSS) of biomass in both reactors were almost similar. This further confirmed that early granulation was induced solely by the polymer and it also had no deleterious impact on substrate transfer.

Removal and Reuse of Collagen, Gelatine and Total Chromium from a Raw Leather Industry Wastewater using a Sequential Up flow Anaerobic Sludge Blanket Digestion (UASB) / Aerobic Forward Osmosis (FO) Reactor Configuration

Collagen, gelatine and total chromium recovery was achieved from the sequential upflow anaerobic sludge blanket digestion (UASB) reactor sludge and concentrate of forward osmosis (FO) treating raw leather industry wastewater. It is aimed to reduce the cost of raw materials in leather industry process by reusing the collagen, gelatine and total chromium from the leather industry process during tanning. The recoveries of collagen and gelatine, total chromium was 78%, 80% and 27% respectively from the waste sludge in UASB process while the recoveries of these chemicals were 95%, 96% and 99% in the concentrate of FO. The maximum 85% CODtotal, 94% CODdissolved, 89% total-N, 88% total-P, 87% color, 87% total chrome (Cr+3 + Cr+6), 86% TOC, 87% SO3-2, 90% percentage of exchangeable sodium, 87% sodium adsorption rate (SAR), 84% sodium carbonate residue (RSC), 92% Cl-1, 92% SO4-2, 93% total salt, 88% B+3, 94% NO3-, 94% NH4+, 99% fecal coliform, 94% TSS, 93% EC25x106 removal efficiencies were measured to output anaerobic UABS reactor in leather industry wastewater. The maximum 99% CODtotal, 99% CODdissolved, 99% total-N, 99% total-P, 99% color, 99% total chrome (Cr+3 + Cr+6), 99% TOC, 99% SO3-2, 99% percentage of exchangeable sodium, 99% sodium adsorption rate (SAR), 99% sodium carbonate residue (RSC), 99% Cl-1, 99% SO4-2, 99% total salt, 99% B+3, 99% NO3-, 99% NH4+, 99% fecal coliform, 99% TSS, 99% EC25x106 removal efficiencies were observed to output aerobic FO reactor in leather industry wastewater. The costs of anaerobic UASB and aerobic FO processes are 0.57 euro and 0.145 euro, respectively, to treat 1 m3 leather industry wastewater. The cost of the consecutive total system is 0.715 euro for the treatment of 1m3 leather industry wastewater. The methane gas obtained in the UABS reactor is electrical energy and the electrical energy income was calculated as 1.9 euro from 1 m3 anaerobic waste sludge. The income to be obtained from the recovery of total chromium, collagen and gelatine from UABS and FO process is 2.75 Euro/l. As a result, the total cost decreases from 1.55 Euro/l to 0.715 Euro/l after aerobic FO process. The cost of these consecutive treatment processes is reduced by the production of methane gas and is increased the recovery of economic chemicals.

New attempts on acidic anaerobic digestion of poly (butylene adipate-co-terephthalate) wastewater in upflow anaerobic sludge blanket reactor

Poly (butylene adipate-co-terephthalate) (PBAT) wastewater is a highly concentrated, acidic, and toxic wastewater generated from biodegradable plastics production. Large amounts of alkali would be consumed when treating PBAT wastewater by anaerobic digestion due to the low pH value. This study employed acidic anaerobic digestion to treat PBAT wastewater and compared to neutral anaerobic digestion. The results indicated that the COD removal rates in the acidic upflow anaerobic sludge blanket (UASB) reactor were 65.5% and 59.9%, respectively at influent pH 6.0 and 5.0 with the COD concentration of around 11,000 mg L−1, and the methane conversion efficiency were 172.5 and 183.8 mLCH4/gCODr (gCODr: COD removed amount), respectively. Correspondingly, the average COD removal and methane conversion efficiency in the neutral UASB reactor were 63.2% and 188.0 mLCH4/gCODr, respectively. The treatment efficiency of acidic and neutral UASB reactors for PBAT wastewater was similar. The hydrogenotrophic methanogenic activity was further enhanced in the acidic UASB reactor compared to the neutral one. The increase of alkalinity in the acidic UASB reactor (2.4 mmol L−1) was higher than the neutral (2.0 mmol L−1). A higher level of syntrophic acetate oxidation bacteria and hydrogenotrophic methanogen was enriched in the acidic UASB reactor, ensuring efficient treatment and saving costs.