Operation of a modified anaerobic baffled reactor coupled with a membrane bioreactor for the treatment of municipal wastewater in Taiwan

Performance evaluation of Anaerobic-Aerobic Hybrid Baffled Reactor Coupled with an Anaerobic Filter treating Landfill Leachate

The Anaerobic Baffled Reactor (ABR) is an effective solution for landfill leachate treatment using an anaerobic fermentation process, which helps to reduce operating costs and sludge volume. To better understand the biological, chemical, and physical processes involved, especially when combining the ABR with an aerobic component, the study aimed to investigate the performance of an Anaerobic-Aerobic Hybrid Baffled Reactor (AABR) that includes an Anaerobic Filter (AF) for treating landfill leachate. This research utilized two glass reactors. The first reactor, designated as AABR-AF, consisted of six independent rectangular glass chambers arranged side by side. The third and sixth chamber designed for aerobic treatment and AF, respectively. The second reactor was used as a control reactor and did not include any aerobic chamber. The highest Removal Efficiencies (REs) for turbidity, COD, BOD, TP, TKN, nitrate, TOC, and TSS in the AABR-AF and ABR-AF were found to be (65.4% and 56.3%), (98.3% and 94.1%), (98.1% and 93.2%), (86.4% and 65%), (89.2% and 76.7%), (81.2% and 64.4%), (88.2% and 79.4%), and (72.4% and 68.5%), respectively. These optimal REs were achieved at an HRT of 48 h and an OLR of 10 kg/m3.d. Also, the highest and the lowest REs in Heavy Metals (HMs) were 89.57% for manganese in AABR-AF and 6.59% for nickel in ABR-AF, in an OLR of 10 kg/m3.d, respectively. The effective removal of Organic Matters (OMs) from landfill leachate using the AABR-AF and ABR-AF was found to be strongly influenced by HRT and OLR. The AABR-AF configuration, featuring a single aerobic chamber in the reactor, exhibited a higher efficiency in removing OMs compared to the ABR-AF configuration.

Feasibility Study of Anaerobic Baffled Reactor Coupled with Anaerobic Filter Followed by Membrane Filtration for Wastewater Treatment

The performance of a Decentralized Wastewater Treatment System (DWTS) comprising an Anaerobic Baffled Reactor (ABR) and an Anaerobic Filter (AF) and Membrane Filtration (MF) module was studied for domestic wastewater treatment. The efficiency of the system was evaluated by running ABR at four different HRTs (14, 12, 10, and 8 h) resulting in COD removal efficiencies of 74, 72, 69, and 65%, respectively. The performance of AF using four different filtration media, i.e., PVC pipe (25 mm), PVC pipe (20 mm), PVC pipe (15 mm), and Kaldnes K3, was determined at optimized HRT (12 h). Among all the filtration media tested, the highest performance efficiency of the system was found with the PVC pipe (20 mm), which showed COD, TP, and TKN removal of 79, 32, and 63%, respectively. The efficacy of the system was proven via significant COD and turbidity removal of 94.6 and 87.2%, respectively, by the combined system.

Agro-industrial wastewater in a circular economy: Characteristics, impacts and applications for bioenergy and biochemicals

The generation of agroindustrial byproducts is rising fast worldwide. The slaughter of animals, the production of bioethanol, and the processing of oil palm, cassava, and milk are industrial activities that, in 2019, generated huge amounts of wastewaters, around 2448, 1650, 256, 85, and 0.143 billion liters, respectively. Thus, it is urgent to reduce the environmental impact of these effluents through new integrated processes applying biorefinery and circular economy concepts to produce energy or new products. This review provides the characteristics of some of the most important agro-industrial wastes, including their physicochemical composition, worldwide average production, and possible environmental impacts. In addition, some alternatives for reusing these materials are addressed, focusing mainly on energy savings and the possibilities of generating value-added products. Finally, this review considers recent research and technological innovations and perspectives for the future.

Degradation kinetics and COD fractioning of agricultural wastewaters from biogas plants applying biofilm respirometry

Stormwater runoff from agricultural silo facilities can be heavily polluted and needs to be treated before discharged. This study investigates biological treatability and kinetic constants of characteristic silo runoffs, applying attached growth systems. For this, respirometry measurements, typically applied in the activated sludge systems (ASM) as a suspended growth, were modified by using adapted biofilm carriers. This allows a determination of degradation kinetic of the biofilm system and a COD fractioning at the same time, which are fundamental values for the design of a full-scale plant. The developed respirometry method was compared with the state-of-the-art method using suspended growth systems and domestic wastewater. Results are comparable with the parameter of the ASM. As stormwater runoff is usually a mixture from different pollution sources, various, typically occurring substrates are investigated regarding degradation kinetics and COD fractions. Wastewater polluted with digestion residue and solid manure showed similar COD fractions as domestic wastewater with an inert fraction Si of 5-6% and a comparatively low rapidly degradable fraction SS of 21-27%. However, wastewater from corn or whole crop silage showed significant better degradation efficiencies and kinetics with an Si of 2-3% and a rapidly degradable fraction of 56-57%. As COD concentrations up to 5000 mg L^-1 for stormwater runoff and up to 60,000 mg L^-1 for silage effluent can be expected, the results not only show the necessity but also prove the feasibility of biological treatment of stormwater runoff from silo works and provide design parameters for adapted treatment systems.

Process performance and microbial community functional structure in a thermophilic anaerobic baffled reactor coupled with biocatalysed electrolysis

In this study, the performances of a conventional anaerobic baffled reactor (ABR) and an ABR combined with microbial electrolysis cells (MECs) for enhancing degradation of volatile fatty acids (VFAs) were evaluated in 55°C. The ABR-MECs system achieved a total chemical oxygen demand (COD) removal rate of 97.2% and a methane yield of 236 ± 5 mL g^-1 COD_removed at organic loading rate (OLR) of 6.9 kg COD m^-3 d^-1, which were higher than those of the ABR with 77.6% and 207 ± 5 mL g^-1 COD_removed, respectively, at OLR of 5.1 kg COD m^-3 d^-1. The pyrosequencing analysis confirmed that the introduction of MECs into ABR was conducive to establishing stable functional communities of syntrophic fatty acids oxidizing bacteria (SFOB), exoelectrogens and hydrogenotrophic methanogens, such as Syntrophobacter (5.4%), Thermodesulfovibrio (2.0%), Methanobacterium (43.8%), Methanolinea (20.4%). The content of unclassified bacteria increased from 12.4% in the ABR system to 52.3% in the ABR-MECs system. In contrast, the proportion of aceticlastic methanogens decreased from 50.1% in the ABR to 24.5% in the ABR-MECs system. The improved performance of the thermophilic ABR-MECs system resulted from phase separation, wide ecological niche and intensification of methanogenesis process via functional microbes, which significantly enhanced the degradation of propionic acid and acetic acid.

Effect of ElasticFiller on Pollutant Removal in Each Compartment of ABR

This study was aimed to explore the effect of elastic filler on pollutant removal in each compartment of anaerobic baffled reactor (ABR), ABR with elastic filler, and ABR without elastic filler were compared. The result showed that elastic filler increased the removal rate of chemical oxygen demand (COD) and suspended solid (SS) in the first compartment, decreased the removal rate of COD and SS in the second and third compartments, and had little effect on the removal rate of COD and SS in the fourth compartment. Elastic filler increased the increase rate of ammonia nitrogen in the first and second compartments, decreased the increase rate of ammonia nitrogen in the third and fourth compartments; elastic filler had little effect on the nitrate nitrogen, nitrite nitrogen, total nitrogen and total phosphorus in each compartment of ABR. In general, elastic filler could improve the removal rate of COD and SS of ABR but had little effect on the increase rate of ammonia nitrogen, the removal rate of nitrate nitrogen, nitrite nitrogen, total nitrogen and total phosphorus. Elastic filler slightly increased the concentration of formic acid, acetic acid, propionic acid, and butyric acid in the first compartment of ABR, and slightly decreased the sum of formic acid and acetic acid in the second, hird and fourth compartments. Elastic filler did not change the composition of dissolved organic matter (DOM)in each compartment of ABR, but changed the kinds and contents of aromatic proteins, soluble microbial products and humic acids in each compartment of ABR. Elastic filler had little effect on ABR in the removal of aromatic proteins, but they could improve the removal rate of soluble microbial products and humicacids. Elastic filler slightly increased the degree of DOM humification (or maturity) in ABR effluent, but did not change the main source of humus like substance and DOM in ABR effluent.

Membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol- and quinoline-containing wastewater: granular activated carbon vs polyaluminum chloride

Although anaerobic membrane bioreactor (AnMBR) has been proposed for the treatment of phenolic wastewater, the membrane fouling is still a major obstacle. The effects of dosing of granular activated carbon (GAC) and polyaluminum chloride (PACl) on the treatment performance and membrane fouling of anaerobic ceramic membrane bioreactor were investigated for treating phenol- and quinoline-containing wastewater. The results suggested that the one-off dosing of GAC resulted in a decrease of protein/carbohydrate ratio, which might account for the aggravation of membrane fouling alongside with the decreased flocs size. Nevertheless, the substrate uptake rates (SUR) of phenol and quinoline, and the specific methanogenic activity of sludge at the GAC dosing stage of experimental reactor (R1) were 8.79 ± 0.63 mg phenol g^-1 MLVSS d^-1, 7.01 ± 0.09 mg quinoline g^-1 MLVSS d^-1 and 0.27 ± 0.01 g COD_CH4 g^-1 MLVSS d^-1, which were 1.69, 3.59 and 1.93 times higher than that of the control reactor (R2). The dosing of PACl reduced the membrane fouling rate by changing the floc structure of sludge, as well as the component of SMP and EPS. However, the substrate uptake rate of quinoline was declined. This work provides a comprehensive evaluation on the effect of GAC and PACl dosing on membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol-and quinoline-containing wastewater.