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[Display omitted] • Dairy wastewater was treated with combined AD and microalgal cultivation. • COD, TN and TP were removed during cultivation of a bacterial-algal consortium. • Highest nutrient removal & biochemicals production were obtained using 25% wastewater. • Co-digestion with 25% resulting algal biomass enhanced biomethane production. A sequential anaerobic digestion and phycoremediation process was employed to recover nutrients and remove pollutants from dairy wastewater (DW), while simultaneously producing biomethane and biochemicals. Anaerobic digestion of 100% DW achieved a methane content and production rate of 53.7% and 0.17 L/L/d, respectively. This was accompanied by the removal of 65.5% chemical oxygen demand (COD), 86% total solid (TS), and 92.8% volatile fatty acids (VFAs). The anaerobic digestate was then used to grow Chlorella sorokiniana SU-1. Using 25% diluted digestate as the medium, SU-1 could reach 4.64 g/L biomass concentration, with total nitrogen (TN), total phosphorus (TP) and COD removal efficiencies of 77.6%, 87.1% and 70.4%, respectively. The obtained microalgal biomass (contained 38.5% carbohydrates, 24.9% proteins, 8.8% lipids) was used to co-digest with DW, resulting in good methane production performance. Co-digestion with 25% (w/v) algal biomass obtained a higher CH 4 content (65.2%) and production rate (0.16 L/L/d) than other ratios. [ABSTRACT FROM AUTHOR]

Dairy wastewater collected from local dairy industry was used as a growth media (without any pre-treatment) for the cultivation of microalgae Acutodesmus dimorphus . The level of COD reduced over 90% (from 2593.33 ± 277.37 to 215 ± 7.07 mg/L) after 4 days of cultivation; whereas, ammoniacal nitrogen was consumed completely (277.4 ± 10.75 mg/L) after 6 days of cultivation. Dry biomass of 840 and 790 mg/L was observed after 4 and 8 days of cultivation, respectively, which is about 5–6 times more than that of BG-11 grown culture (149 mg/L after 8 days). This biomass contains around 25% lipid and 30% carbohydrate, which can be further converted into biodiesel and bioethanol, respectively. Theoretical calculations based on the recently reported conversion yield suggest that 1 kg biomass of A. dimorphus might produce around 195 g of biodiesel and 78 g of bioethanol, which sums up to 273 g of biofuels. [ABSTRACT FROM AUTHOR]

In sequencing batch reactors (SBRs) treating dairy wastewaters, the overgrowth of filamentous bacteria is a frequent cause of operational problems. The present study aimed at understanding to what extent the operating conditions of a SBR can be optimized to convert a bulking activated sludge into a well-settling biomass at low aeration velocity. The abundance of filament morphotypes and floc-formers able to store biopolymers were analysed by PCR-DGGE and 16S amplicon sequencing. The results indicated that a combination of an anaerobic-microaerated feeding pattern with a low selective pressure was beneficial to supress filamentous overgrowth and to form aerobic granules, while increasing the efficiency of suspended solid removal. Average removal efficiencies for total chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were 94 ± 2%, 95 ± 1% and 83 ± 13%, respectively. [ABSTRACT FROM AUTHOR]

This study evaluated the potential of a microalga Diplosphaera sp. MM1 for its ability to generate energy through biomass production from wastewater remediation. 33% dairy wastewater and 50% winery wastewater demonstrated as promising alternative media for cultivating Diplosphaera sp. MM1 biomass. Interestingly, the alga cultivated in 50% winery wastewater with limited nitrogen produced the highest lipid content (43.07% total solid) and the lowest carbohydrate content (9.35% TS). On the contrary, the lowest lipid content (16.98% TS) and the highest carbohydrate content (29.39% TS) were exhibited by the alga cultivated in 33% dairy wastewater. The results from anaerobic digestion processes in terms of biochemical methane potential of the alga cultivated in BG-11 medium, 33% dairy wastewater and 50% winery wastewater were 197.39, 129.75 and 218.51 NmL g −1 VS, respectively. Further, this study demonstrates the potential of winery wastewater as a candidate to increase the lipid content of algae and enhance biofuel production of algal biomass. [ABSTRACT FROM AUTHOR]

This study demonstrated that the limiting factor to algae growth on dairy wastewater was the ammonia nitrogen deficiency. Dairy wastewaters were mixed with a slaughterhouse wastewater that has much higher ammonia nitrogen content. The results showed the mixing wastewaters improved the nutrient profiles and biomass yield at low cost. Algae grown on mixed wastewaters contained high protein (55.98–66.91%) and oil content (19.10–20.81%) and can be exploited to produce animal feed and biofuel. Furthermore, algae grown on mixed wastewater significantly reduced nutrient contents remained in the wastewater after treatment. By mitigating limiting factor to algae growth on dairy wastewaters, the key issue of low biomass yield of algae grown on dairy wastewaters was resolved and the wastewater nutrient removal efficiency was significantly improved by this study. [ABSTRACT FROM AUTHOR]

The anaerobic co-digestion of dairy wastewater (DW) and cattle manure (CM) was examined and associated with microbial community’s structures using Denaturing Gradient Gel Electrophoresis (DGGE). The highest volatile solids (VS) reduction yield of 88.6% and biogas production of 0.87 L/g VS removed were obtained for the C/N ratio of 24.7 at hydraulic retention time (HRT) of 20 days. The bacterial DGGE profile showed significant abundance of Uncultured Bacteroidetes, Firmicutes and Synergistetes bacterium. The Syntrophomonas strains were discovered in dependent association to H 2 -using bacteria such as Methanospirillum sp., Methanosphaera sp. and Methanobacterium formicicum . These syntrophic associations are essential in anaerobic digesters allow them to keep low hydrogen partial pressure. However, high concentrations of VFA produced from dairy wastes acidification allow the growth of Methanosarcina species. The application of the stabilised anaerobic effluent on the agriculture soil showed significant beneficial effects on the forage corn and tomato plants growth and crops. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report on the optimization of citric acid (CA) using banana pseudostem. • The optimized process gave a maximum CA concentration of 14.408 g/L. • Kinetics were determined on fresh water, wastewater and standard medium. • The wastewater-based bioprocess demonstrated only a 9.11% lower CA concentration. • Findings facilitate the development of waste-based lignocellulosic bioprocesses. This study optimized the simultaneous saccharification and citric acid (CA) production from banana pseudostem (BP). Thereafter, kinetic assessment of Aspergillus brasiliensis growth and CA production were determined for the optimum conditions using fresh water (SSF optimizedFW) or dairy wastewater (SSF DWW) and compared to Sabouraud Dextrose Emmon's medium modified with BP (SSF SDEmodified). The optimized conditions gave a CA concentration of 14.408 g/L. Kinetic assessment revealed the same maximum specific growth rates (μ max) (0.05 h−1) for all three bioprocesses, while the SSF SDEmodified process resulted in the highest maximum potential CA concentration (P m) (13.991 g/L) in comparison to the SSF DWW (P m = 13.095 g/L) and SSF optimizedFW (P m = 12.967 g/L) systems. Findings from this study facilitates the implementation of waste-based lignocellulosic bioprocesses that may eradicate the use of expensive pretreatment chemicals, fermentation medium constituents, and resources, in keeping with the water, energy and food nexus towards developing a circular bioeconomy. [ABSTRACT FROM AUTHOR]

The biomass productivity and nutrient removal capacity of simultaneous Chlorella sp. cultivation for biodiesel production and nutrient removal in raw dairy wastewater (RDW) in indoor bench-scale and outdoor pilot-scale photobioreactors were compared. Results from the current work show that maximum biomass productivity in indoor bench-scale cultures can reach 260 mg L −1 day −1 , compared to that of 110 mg L −1 day −1 in outdoor pilot-scale cultures. Maximum chemical oxygen demand (COD), total nitrogen (TN), and total phosphorous (TP) removal rate obtained in indoor conditions was 88.38, 38.34, and 2.03 mg L −1 day −1 , respectively, this compared to 41.31, 6.58, and 2.74 mg L −1 day −1 , respectively, for outdoor conditions. Finally, dominant fatty acids determined to be C16/C18 in outdoor pilot-scale cultures indicated great potential for scale up of Chlorella sp. cultivation in RDW for high quality biodiesel production coupling with RDW treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Immobilized microbial technology with PUF can effectively treat dairy wastewater. • The removal efficiencies of COD, TN and NH 3 -N all reached to 96%. • Acinetobacter were the dominant bacteria in the reactor. The development of dairy industry is accompanied by large volumes of wastewater production, which is threaten to human's health and the biosphere. In this study, synthetic dairy wastewater was treated by immobilized microbial technology using polyurethane foam as carrier. Batch experiments were conducted to determine the effects of different operational parameters, and an up-flow immobilized microbial reactor was built to investigate long-term performance of the system. Batch experiments showed that COD, TN and NH 3 -N dropped from 1932, 51.33 and 51.42 mg·L−1 to 75.3, 5.17 and 4.54 mg·L−1 after 48 h, respectively, at the optimum conditions (25 °C, pH 6.0). Besides, the reactor can remove 97.33% of COD, 96.46% of TN and 99.55% of NH 3 -N with HRT of 24 h, which the average volume load was 1.93 kg COD·(m3·d)−1. The analysis of microbial community determined that dominant bacteria at genus level were Acinetobacter , Fusibacter , Nannocystis and norank _f_NS9_marine_group. [ABSTRACT FROM AUTHOR]

Highlights: [•] The design parameters of a microbial fuel cell were obtained by Genetic Algorithm. [•] The parameters are validated using experimental results. [•] The performance of MFC was simulated by conduction-based model. [•] Concentration polarization had approximately the same effect as ohmic one. [Copyright &y& Elsevier]

Abstract: In this study, the granular sludge was generated for simultaneous nitrification, denitrification and phosphorus removal (SNDPR) and studied on a laboratory scale. Analyzing the nutrients removal percentages from wastewater were scrutinized by using an optimization of the variables, i.e., COD:N:P ratio, OLR, aeration time, MLSS, F:M and HRT. These 6 interrelated parameters were evaluated as the process response. Microscopic observations of the performance of the SNDPR process revealed that the granules included Bacillus sp. in the bacterial community. According to these results, the UAASB system produced an effluent that lends dairy wastewater suitable for land irrigation and that this an attractive process of using granular sludge is appropriate for achieving carbon, nitrogen and phosphorus removal from nutrient-rich wastewater by a biological method. [Copyright &y& Elsevier]

Highlights: [•] Energy generation from dairy wastewater was investigated using dual chambered MFC. [•] Anaerobic metabolism showed higher current efficiency than aerobic metabolism. [•] Aerobic metabolism showed higher power generation capacity. [•] MFC operate at pH 7 and COD concentration of 1660mg/L showed better performance. [•] MFC operation using a buffer for pH maintenance given better power generation. [Copyright &y& Elsevier]

Abstract: This study analyzed dairy wastewater fermentation in convection- and microwave-heated hybrid reactors at loadings of 1 and 2kgCOD/(m3 d) and temperatures of 35 and 55°C. The biomass was investigated at a molecular level to determine the links between the operational parameters of anaerobic digestion and methanogenic Archaea structure. The highest production of biogas with methane content of ca. 67% was noted in the mesophilic microwave-heated reactors. The production of methane-rich biogas and the overall diversity of Archaea was determined by Methanosarcinaceae presence. The temperature and the application of microwaves were the main factors explaining the variations in the methanogen community. At 35°C, the microwave heating stimulated the growth of highly diverse methanogen assemblages, promoting Methanosarcina barkeri presence and excluding Methanosarcina harudinacea from the biomass. A temperature increase to 55°C lowered Methanosarcinaceae abundance and induced a replacement of Methanoculleus palmolei by Methanosarcina thermophila. [Copyright &y& Elsevier]

Abstract: An anaerobic/aerobic filter (AF/BAF) system was developed treating dairy wastewater. The influent was blended with recirculated effluent to allow for pre-denitrification in the AF followed by nitrification in the BAF. The recirculation ratio ranged 100–300%. The average chemical oxygen demand (COD) removal efficiency was 79.8–86.8% in the AF and the average total nitrogen removal efficiency was 50.5–80.8% in the AF/BAF system. Steady-state mass balances on the AF were used to analyze removal kinetics in the AF. The kinetic model values for effluent COD in the AF were overestimated as compared with experimental data. The integrated suspended and attached biomass growth rates in the AF were estimated. The specific growth rate of the integrated biomass at each recirculation ratios was 0.6213, 0.6647, and 1.20831/day, respectively. The increase in specific growth rate corresponded to increases in biomass sloughing as the recirculation ratio increased. [Copyright &y& Elsevier]

Abstract: A two-stage ultrafiltration and nanofiltration (UF/NF) process for the treatment of model dairy wastewater was investigated to recycle nutrients and water from the wastewater. Ultracel PLGC and NF270 membranes were found to be the most suitable for this purpose. In the first stage, protein and lipid were concentrated by the Ultracel PLGC UF membrane and could be used for algae cultivation to produce biodiesel and biofuel, and the permeate from UF was concentrated by the NF270 membrane in the second stage to obtain lactose in retentate and reusable water in permeate, while the NF retentate could be recycled for anaerobic digestion to produce biogas. With this approach, most of dairy wastewater could be recycled to produce reusable water and substrates for bioenergy production. Compared with the single NF process, this two-stage UF/NF process had a higher efficiency and less membrane fouling. [Copyright &y& Elsevier]

Abstract: The aim of this study was to develop an input/output mass balance to predict phosphorus retention in a five pond constructed wetland system (CWS) at Greenmount Farm, County Antrim, Northern Ireland. The mass balance was created using 14-months of flow data collected at inflow and outflow points on a weekly basis. Balance outputs were correlated with meteorological parameters, such as daily air temperature and hydrological flow, recorded daily onsite. The mass balance showed that phosphorus retention within the system exceeded phosphorus release, illustrating the success of this CWS to remove nutrients from agricultural effluent from a dairy farm. The last pond, pond 5, showed the greatest relative retention of 86%. Comparison of retention and mean air temperature highlighted a striking difference in trends between up-gradient and down-gradient ponds, with up-gradient ponds 1 and 2 displaying a positive quadratic relationship and down-gradient ponds 3 through 5 displaying a negative quadratic relationship. [Copyright &y& Elsevier]

Abstract: Present study reports treatment of synthetic dairy wastewater (SDW) in terms of chemical oxygen demand (COD) removal by means of adsorption onto activated carbon-commercial grade (ACC) and bagasse fly ash (BFA). Optimum conditions for SDW treatment were found to be: initial pH≈4.8, adsorbent dose of 20g/l for ACC and 10g/l for BFA and contact time ≈8h. Pseudo-second-order kinetic model was found to fit the kinetic data and Redlich–Peterson isotherm model was generally found to best represent the equilibrium data for SDW treatment by ACC and BFA. The change in entropy and enthalpy for SDW adsorption onto ACC and BFA were estimated as 125.85kJ/molK and 91.53kJ/mol; and 25.71kJ/molK and 17.26kJ/mol, respectively. The negative values of change in Gibbs free energy indicate the feasibility and spontaneous nature of the adsorptive treatment. [Copyright &y& Elsevier]

Abstract: The effect of a lipase-rich fungal enzymatic preparation, produced by a Penicillium sp. during solid-state fermentation, was evaluated in an anaerobic digester treating dairy wastewater with 1200mg of oil and grease/L. The oil and grease hydrolysis step was carried out with 0.1% (w/v) of solid enzymatic preparation at 30°C for 24h, and resulted in a final free acid concentration eight times higher than the initial value. The digester operated in sequential batches of 48h at 30°C for 245days, and had high chemical oxygen demand (COD) removal efficiencies (around 90%) when fed with pre-hydrolyzed wastewater. However, when the pre-hydrolysis step was removed, the anaerobic digester performed poorly (with an average COD removal of 32%), as the oil and grease accumulated in the biomass and effluent oil and grease concentration increased throughout the operational period. PCR-DGGE analysis of the Bacteria and Archaea domains revealed remarkable differences in the microbial profiles in trials conducted with and without the pre-hydrolysis step, indicating that differences observed in overall parameters were intrinsically related to the microbial diversity of the anaerobic sludge. [Copyright &y& Elsevier]

Abstract: Nozzle-cavitation treatment was used to reduce excess sludge production in a dairy wastewater treatment plant. During the 450-d pilot-scale membrane bioreactor (MBR) operation, when 300l of the sludge mixed liquor (1/10 of the MBR volume) was disintegrated per day by the nozzle-cavitation treatment with the addition of sodium hydrate (final concentration: 0.01% W/W) and returned to the MBR, the amount of excess sludge produced was reduced by 80% compared with that when sludge was not disintegrated. On the basis of the efficiency of CODCr removal and the ammonia oxidation reaction, it was concluded that the nozzle-cavitation treatment did not have a negative impact on the performance of the MBR. The estimation of the inorganic material balance showed that when the mass of the excess sludge was decreased, the inorganic content of the activated sludge increased and some part of the inorganic material was simultaneously solubilized in the effluent. [Copyright &y& Elsevier]

Abstract: Main goal of the study was present the results of some respirometric measurements of activated sludge biodegrading the substrate in the wastewater originated in selected sections of the dairy processing line. The following dairy production effluents were analyzed in the research: the pumping station wastewater (combined wastewater from all the sections of the dairy factory), the apparatus room wastewater, the butter section wastewater, the milk reception point wastewater, the cheese section wastewater and the cottage cheese section wastewater. Apart from that, sweet and sour whey, which are secondary products of hard cheese and cottage cheese production, respectively, was the subject of the research. The amount of organic matter being oxidized during a 5-day measurement session was calculated on 1g of the activated sludge biomass. The research was conducted at the temperature of 20°C and 35°C at the applied sludge loading rate of A′ =0.2g BODg−1 dry massd−1, which ensured complete biodegradation. The results indicated a correlation between a technological process of dairy processing, an ultimate outcome of which was the wastewater analyzed, and dairy wastewater biodegradability. The results confirmed that all dairy processing effluents can be treated together, with the exception of whey, whose complex biodegradation demands may cause too much burden to any wastewater treatment technological system and thus should be managed within a separate installation. [Copyright &y& Elsevier]

Abstract: Two anaerobic sludges previously loaded with oleate and palmitate accumulated 4570±257 and 5200±9mgCOD-LCFAgVSS−1, respectively. These sludges were incubated in batch assays and methane production was recorded after addition of 100–900mgL−1 of oleate and palmitate, respectively. The batch assays were conducted before and after allowing the depletion of the biomass-associated LCFA. The presence of biomass-associated LCFA decreased the capacity of both sludges to convert the added LCFA to methane. After the degradation of biomass-associated LCFA, the lag phases observed before the onset of methane production were significantly reduced, evidencing an increase in the tolerance of the acetotrophic methanogens to the presence of LCFA. In another experiment, three recurrent pulses were performed with a real dairy wastewater containing 3.6gCODL−1, from which 53% was fat. Methane yields of 0.45±0.01, 0.88±0.02 and 1.29±0.08gCOD- were achieved in the first, second and third pulses, respectively, evidencing an increasing capacity of the sludge to convert substrate accumulated in previous additions. [Copyright &y& Elsevier]

Abstract: Influence of different pretreatment methods applied on anaerobic mixed inoculum was evaluated for selectively enriching the hydrogen (H2) producing mixed culture using dairy wastewater as substrate. The experimental data showed the feasibility of molecular biohydrogen generation utilizing dairy wastewater as primary carbon source through metabolic participation. However, the efficiency of H2 evolution and substrate removal efficiency were found to be dependent on the type of pretreatment procedure adopted on the parent inoculum. Among the studied pretreatment methods, chemical pretreatment (2-bromoethane sulphonic acid sodium salt (0.2g/l); 24h) procedure enabled higher H2 yield along with concurrent substrate removal efficiency. On the contrary, heat-shock pretreatment (100°C; 1h) procedure resulted in relatively low H2 yield. Compared to control experiments all the adopted pretreatment methods documented higher H2 generation efficiency. In the case of combination experiments, integration of pH (pH 3; adjusted with ortho-phosphoric acid; 24h) and chemical pretreatment evidenced higher H2 production. Data envelopment analysis (DEA), a frontier analysis technique model was successfully applied to enumerate the relative efficiency of different pretreatment methods studied by considered pretreatment procedures as input and cumulative H2 production rate and substrate degradation rate as corresponding two outputs. [Copyright &y& Elsevier]

Abstract: Recirculation of fully nitrified effluent from a laboratory horizontal-flow biofilm reactor (HFBR) to a mixed pre-denitrification reactor (DR) was used to remove organic carbon and nitrogen from synthetic dairy wastewater. Three recirculation ratios of 2, 4, and 6 were examined in this study and the average filtered chemical oxygen demand (CODf) and total nitrogen (TN) removals were up to 97.4% and 85.5%, respectively, at 11°C. In the DR, the nitrate nitrogen removal efficiencies and rates were 86–96% and 22–34gN/m3 d. In the HFBR, the ammonium nitrogen removal rates were 293–337mgN/m2 d. [Copyright &y& Elsevier]

Abstract: This study examined the behaviour of the microbial population in an anaerobic reactor, in terms of changes in numbers of total bacterial community, autofluorescent methanogens, non-methanogens and morphology of the autofluorescent methanogens, using epifluorescence microscopy and microbiological enumeration techniques. A laboratory-scale, continuous flow-completely mixed anaerobic reactor, coupled with a conventional gravity settling tank and a continuous recycling system, was operated at an HRT range between 24 and 12h, using dairy wastewater as the substrate. The numbers of the total bacterial community and autofluorescent methanogens both decreased during start-up. Also, the proportion of the number of autofluorescent methanogens in the total bacterial community varied from 5% to 16% during operation. In particular, the activity of the methane-forming bacteria decreased significantly at HRTs of 16 and 12h. A membrane module, instead of a conventional settling tank, would obviously have been a more effective method if recycling were required in the anaerobic treatment system. [Copyright &y& Elsevier]

In Ireland, wastewaters emanating from the food industry typically contain elevated levels of nitrogen and phosphorus before treatment. Two pilot scale studies were performed to determine the feasibility of achieving biological N and P removal on-site at a food ingredients plant. The wastewater treated by the pilot reactors was that which resulted from the day-to-day production in the full-scale food ingredients plant. Both reactors were of the anaerobic/anoxic/oxic (A/A/O) design, however the sizing of the zones was varied in this study. In the first pilot study, while treating a wastewater of the following strength: 1008 mg COD/l; 30.1 mg NH4-N/l and 26.7 mg P/l, removal efficiencies of 93%, 99% and 98% were obtained for COD, NH4-N and P, respectively. In the second study, while operating at reduced hydraulic retention times and lower recycle rates, the pilot plant treated a wastewater of the following strength: 1757 mg COD/l; 62 mg NH4-N/l and 57 mg P/l, with removal efficiencies of 94%, 97% and 75% obtained for COD, NH4-N and P, respectively. This work showed that biological nutrient removal could be successfully applied to treatment of food industry wastewaters. [Copyright &y& Elsevier]

• Ultrasound, ozone and US combined with ozone pretreatments were investigated. • US/ozone pretreatment was effective in the inactivation of indicator bacteria. • Antibiotic resistance genes could not be decreased in absolute concentration. • Pretreatments could reduce the relative abundance of antibiotic resistance genes. • Methane production increased by 10% by 20 min ozone and US/ozone pretreatment. In this study, the effect of ultrasound (US), ozone and US combined with ozone (US/ozone) pretreatments on the fate of enteric indicator bacteria and antibiotic resistance genes (ARGs), and anaerobic digestion (AD) of dairy wastewater was investigated. The pretreatment conditions included US power 200 W, ozone concentration 4.2 mg O 3 /L, and pretreatment time 0–30 min. The results showed that US/ozone pretreatment was effective in the inactivation of enteric indicator bacteria. Total coliforms and enterococci were reduced by 99% and 92% after 30 min US/ozone pretreatment. Pretreatments could not decrease ARGs in absolute concentration, but could decrease ARGs in relative abundance. In the subsequent AD process, methane production increased more than 10% with 20 min ozone or 20 min US/ozone pretreatments. Pretreatment-AD together obviously inhibited the enrichment of ARGs in relative abundance. This study provided a pretreatment way to enhance methane production and to prevent the enrichment of ARGs. [ABSTRACT FROM AUTHOR]

• High-rate anaerobic treatment of dairy wastewater is feasible at 15 °C. • Reactor configuration is an important consideration. • Protein degradation was identified as a rate-limiting step at low-temperatures. • low-temperatures reduced microbial diversity, but performance remained stable. • Lactococcus was identified as a potential key genus. Low temperature anaerobic digestion remains in its infancy, despite increasing interest for the treatment of complex wastewaters. In this study, the feasibility of low-temperature anaerobic treatment of dairy wastewater was assessed during a 443-day laboratory-scale bioreactor trial. The bioreactors were operated in triplicate at organic loading rates of 7.5–9 kgCODm−3d−1 throughout five operational phases. The structure of the microbial community was analysed using quantitative real-time PCR and amplicon sequencing of 16S rRNA genes from DNA and rRNA. The results indicated that low-temperature treatment of dairy wastewater is feasible at 15 °C, but that reactor configuration remains extremely important. The upflow anaerobic sludge bed (UASB) configuration out-performed the expanded granular sludge bed (EGSB)-based configurations. Decreased temperatures resulted in significant reductions in microbiome diversity. Methanosaeta was identified as a dominant genus throughout the trial, while Lactococcus was identified as an important bacterial genus at low-temperatures. However, the relative abundance of Lactococcus was significantly influenced by reactor configuration. [ABSTRACT FROM AUTHOR]