Piggery Wastewater Treatment Research Articles

Effect of integrated microbial fuel cell in a two-stage vertical flow constructed wetland for piggery wastewater treatment and resource recovery by photobioreactor

ABSTRACT This study developed a nature-based pilot-scale technology for simultaneous piggery WW treatment and resource recovery potential. The technology comprised a two-stage vertical flow constructed wetland (2-VFCW) integrated with a microbial fuel cell (MFC) and microalgal photobioreactor. The first and second stage was an unsaturated and saturated type, respectively. The bioelectricity generation was optimised by investigating the suitable electrode zonation, hydraulic retention time (HRT) and WW loading rate. The 2-VFCW-MFC-treated effluent was studied to grow microalgae for biomass production. The 2-VFCW-MFC showed better treatment efficiency than the 2-VFCW, possibly due to enhanced microbial activity on the electrode surface, leading to improved organic matter degradation and electron transfer to the cathode, enhancing NO3− and PO43− reduction. The 2-VFCW-MFC with electrode zonation of 20 cm (cathode) and 60 cm (anode) and HRT of 76 h, 48 min showed the highest open-circuit voltage of 291.83+13.53 mV and WW treatment efficiency. The highest algal biomass of 21,323.34+8,316.26 mg/L (wet weight) was produced at HRT of 96 h, then entered the death phase. Comparatively, the 2-VFCW-MFC showed higher WW treatment efficiency than 2-VFCW at 2 L/day by 23.24% COD, 27.43% TOC, 33.05% PO43−, 13.51% NO3−, 8.14% TN, except TAN (22.71%).

Anaerobic hybrid-photobioreactor using phototrophic purple and green bacteria treating piggery wastewater with sulfur recovery and biogas polishing

An anaerobic hybrid-photobioreactor (AnHPBR) was performed for biogas polishing during piggery wastewater treatment. AnHPBR was exposed to high (4.45 × 105 lx) and low (450 lx) light intensities for growing purple and green sulfur phototrophs separately in each chamber of AnHBBR for soluble sulfide removals. Four phases of hydraulic retention times (HRT, h): 24, 48, 96, and 96 (with added sulfate) of piggery wastewater were operated consecutively for 351 days. Metagenomic analysis of the AnHPBR biomass confirmed that purple and green bacteria were 63–82 %, of which the species varied by HRT and sulfate loadings. In sum, 96 h HRT for AnHPBR presented the highest efficacies in removals of COD (92 %), sulfate (73 %), and sulfide (59 %). Its biogas contained high methane (75 %) and low hydrogen sulfide (0.3 %). Additionally, AnHPBR produced outflow biosolids with a stable sulfur content of 1.88 %.

Effects of rice husk biochar attachment biofilm with microorganisms on nitrogen removal of digested swine wastewater

Nitrogen in digested swine wastewater is currently difficult to directly degrade by an activated sludge process in a sequencing batch reactor (SBR), with resulting failure of the effluent to meet emission standards. In this study, rice husk biochar was optionally added into SBR to enhance biochemical properties for digested swine wastewater, especially for nitrogen degradation. The relative nitrogen removal mechanism for microbial community was probed by means of high-throughput sequencing. The results indicated that chemical oxygen demand (COD), ammonia (NH4+-N), and total nitrogen (TN) removal efficiency of digested swine wastewater was separately at 85.3%, 81.3%, and 65.2% using rice husk biochar with biofilm, which was 3.5%, 24.4%, and 14.7% higher than that of activated sludge, under influent of 2609 mg·L-1 COD, 337.0 mg·L-1 NH4+-N, 344 mg/L TN, and 7.77 C/N. High-throughput sequencing revealed that rice husk biochar with biofilm contained Proteobacteria, Thauera, Comamonas, Acinetobacter, Pseudomonas, Flavobacterium, and Corynebacterium to enhance nitrogen removal of digested swine wastewater. The results not only provide theoretical support for biochar with biofilm to improve digested piggery wastewater treatment, but also have great significance in resource utilization of agricultural waste and eco-environmental protection.

Aerobic Granular Sludge Treatment of Piggery Wastewater: Solution to the Problem of Non-Filamentous Bulking and Analysis of Microbial Community Structure in Practical Application

Aerobic Granular Sludge Treatment of Piggery Wastewater: Solution to the Problem of Non-Filamentous Bulking and Analysis of Microbial Community Structure in Practical Application

Development of an artificial neural network (ANN) for the prediction of a pilot scale mobile wastewater treatment plant performance

Productive activities such as pig farming are a fundamental part of the economy in Mexico. Unfortunately, because of this activity, large quantities of wastewater are generated that have a negative impact in the environment. This work shows an alternative for treating piggery wastewater based on advanced oxidation processes (Fenton and solar photo Fenton, SPF) that have been probed successfully in previous works. In the first stage, Fenton and SPF were carried out on a laboratory scale using a Taguchi L9-type experimental design. From the statistical analysis of this design, the operating parameters: pH, time, hydrogen peroxide concentration [H2O2], and iron ferrous concentration [Fe2+] that maximize the response variables: Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), and color were chosen. From these, a cascade forward neural network was implemented to establish a correlation between data from the variables to the physicochemical parameters to be measure being that a great fit of the data was obtained having a correlation coefficient of 0.99 which permits to optimize the pollutant degradation and predict the removal efficiencies at pilot scale but with a projection to a future industrial scale. A relevant result, it was found that the optimal values for maximizing the removal of physicochemical parameters were pH = 3, time = 60 min, H2O2/COD = 1.5 mg L−1, and H2O2/Fe2+ = 2.5 mg L−1. With these conditions degradation percentages of 91.44%, 47.14%, and 97.89% for COD, TOC, and color were obtained from the Fenton process, while for SPF the degradation percentage increased moderately. From the ANN analysis, the possibility to establish an intelligent system that permits to predict multiple results from operational conditions has been achieved.

Impact of truncated modified basalt fibers on aerobic granular sludge stability and pollutant removal in piggery wastewater treatment

Modified basalt fibers (MBF) and carbon fibers (CF) are effective bio-carrier materials that enhance wastewater treatment performance. This study explored the use of two lengths of truncated MBF and CF (0.1 and 0.4 mm) in a sequencing batch reactor to support activated sludge treatment, facilitating the formation of aerobic granular sludge (AGS). This approach aimed to enhance the stability and pollutant removal efficiency of AGS, particularly for treating piggery wastewater (PWW). The study further assessed the impact of adding truncated fibers on AGS formation, stability, and its chemical oxygen demand (COD) and total nitrogen (TN) removal capabilities. Results indicate that truncated MBF notably enhanced sludge activity, promoting the secretion of extracellular polymeric substances (EPS) within AGS. This process further increased the protein/polysaccharide ratio and bolstered AGS stability. Specifically, the addition of 0.1 mm MBF boosted PWW treatment efficiency. Fluorescence in situ hybridization (FISH) revealed that the addition of fibers had a minimal impact on the distribution of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) within AGS, although truncated MBF enriched the population of AOB. Microbial community analysis showed that the addition of MBF favored the enrichment of bacteria associated with nitrogen removal, upregulating the tricarboxylic acid cycle, nitrogen and amino acid metabolism. Overall, truncated MBF significantly improved AGS stability and its effectiveness in PWW treatment.

Veterinary antibiotics and metals impact the mass, composition and hydrolysis of biomass cultivated in piggery wastewater treatment photobioreactors

Photobioreactors are a promising alternative for piggery wastewater treatment which allows to produce valuable biomass, but the presence of antibiotics or heavy metals in the pig manure can influence the biomass composition and the posterior valorization processes. This study evaluates the effect of these pollutants on mass, composition and hydrolysis yields of the consortia of microalgae and bacteria obtained in a 1280 L photobioreactor treating pig manure. The photobioreactor feed was doped with 1) veterinary antibiotics; 2) copper, zinc, and arsenic; and 3) combination of both pollutants. The pollutants presence decreased the mass of biomass grown in the photobioreactor by up to 35% while glucose content of the biomass by up to 42% and increased protein and xylose by 30% and 16% due to oxidative stress. Likewise, they increased the protein solubilization yield by acid hydrolysis at 120 ºC by 32% while reduced glucose solubilization by 49% after alkaline hydrolysis at 120 ºC. Applying enzymatic hydrolysis and ultrasound assisted enzymatic extractions, glucose and xylose recoveries were drastically reduced in presence of heavy metals (∼100%). Antibiotics increased xylose solubilization by ultrasonication (74%), but also its degradation, decreasing xylose recovery. Thus, the presence of all these pollutants in pig manure affected biomass production and valorization and these results must be considered for biorefinery processes.

Mixotrophic denitrification: A study on the removal of high nitrate concentration from piggery wastewater by biofilter reactors

The treatment of piggery wastewater through anaerobic fermentation and subsequent irrigation on farmland has been found to pose a risk of nitrate-nitrogen pollution in groundwater, thereby posing potential threats to human health. The scientific investigation of employing heterotrophic/autotrophic (mixotrophic) denitrification as a means to address the issue of farm wastewater containing elevated levels of nitrate nitrogen has garnered significant attention. This study employed sulfur monomers, limestone, and corn cob as microbial carriers within a biofilter system to facilitate the heterotrophic denitrification process of piggery wastewater fermentation broth. The efficacy of mixotrophic denitrification was found to surpass that of sulfur-limestone autotrophic denitrification in the treatment of nitrate-nitrogen wastewater with elevated concentrations of nitrate-nitrogen. This was evidenced by higher rates of denitrification, as well as reduced production of sulphate ions and alkalinity. The experiments on mixotrophic denitrification reaction observed a positive correlation between the content of corn cob and the relative abundance of microbial flora. Specifically, the relative abundance of Proteobacteria at the phylum level showed an increasing trend. Additionally, there was a proportional increase in the relative abundance of various other flora at the genus level.

Detailed investigation of bio-foam characteristics of piggery wastewater reveals long chain fatty acids-dominated foaming mechanisms

Biological foam has seriously troubled the wastewater treatment process and brings significant challenges to effluent quality, process efficiency, and operation safety. This study systematically analyzed the characteristics of biological foam from three typical piggery wastewater treatment stations, identified the key substances causing biological foam, and revealed potential foaming mechanisms. Foaming characteristics evaluation indicated that, for piggery wastewater, the low surface tension (58.9– 69.7 mN·m−1) was the crucial factor leading to strong foaming capacity (r = −0.761), and high viscosity (0.24– 0.7 Pa·s) and zeta potential (−10.4 ∼ −15.3 mV) increased the foam stability (r = 0.857, −0.767, respectively). Multidimensional correlation analysis revealed that the long-chain fatty acids (LCFAs) in the influent of piggery wastewater were the key leading to the foaming issue, and their influences had two paths: the decrease of surface tension caused by LCFAs could directly induce a stronger foaming capacity (physicochemical path); moreover, LCFAs favored the enrichment of non-filamentous foam-related microbes (abundance >3.3 %) like Hydrogenophaga and Pseudomonas spp. to secrete more extracellular polymeric substances, increasing the viscosity and zeta potential to maintain the foam stability (biological paths). Based on the revealed foaming mechanism dominated by LCFAS, this study provided novel insight and valuable guidance for efficient and safe treatment of piggery wastewater.

Piggery wastewater treatment with a Chlorella microalgae-bacteria consortium and static magnetic field

Wastewater discharges into the environment without adequate treatment is a problem still unresolved. That is why alternative technologies, such as applying static magnetic field (SMF), are currently being sought. The objective of this research was to evaluate the effect of a 47.23 mT SMF on the removal of nitrogen (N), phosphorus (P), and the growth of a Chlorella microalgae-bacteria consortium grown in piggery wastewater under different photoperiods. SMF application increased culture productivity, with maximum values of 0.030 g/ Ld−1 in cultures exposed to SMF in a 16:8 h light/dark photoperiod and 0.038 g/ Ld−1 for the 24:0 h light/dark photoperiod. Furthermore, SMF application increased the microorganisms' photosynthetic efficiency (QY), regardless of the photoperiod used. No significant differences were observed on day 21 regarding nutrient removal between the treated and control cultures. Removal percentages of 93.41 % N and 95.56 % P were obtained for the cultures exposed to SMF in the 16:8 h light/dark photoperiod, and 94.78 % N and 95.59 % P for cultures exposed to SMF during the 24:0 h light/dark photoperiod. In general, SMF acts mainly on the growth of microorganisms.

Influence of pH on the performance of anaerobic piggery wastewater treatment coupled with membrane-based NH3 extraction

The influence of the pH of piggery wastewater (PWW) on both ammonia recovery and anaerobic digestion performance during PWW treatment was evaluated in a continuous stirred tank reactor coupled with a membrane-based extraction module. The anaerobic digester was operated at a hydraulic retention time of 20 days at 37 °C, while the flat sheet PTFE membrane module operated continuously at liquid recirculation rates of 250 mL min−1. The membrane module was able to gradually decrease the total ammoniacal concentration from 1.27 ± 0.01 to 0.62 ± 0.01 g L−1 after 360 days of operation. Membrane-based NH3 extraction induced a CH4 yield increase of 1.3-fold. Moreover, COD and VS removal efficiencies increased up to 1.2-fold and 1.5-fold, respectively, along with the increase in PWW pH from 7.5 to 12. Total VFAs removal efficiencies were higher at a PWW pH of 9.

Combined zeolite-based ammonia slow-release and algae-yeast consortia to treat piggery wastewater: Improved nitrogen and carbon migration

Integration of zeolite-based ammonia adsorption and algae-yeast consortia was developed to remediate piggery wastewater (PW) containing high concentrations of total ammonia nitrogen (TAN) and total organic carbon (TOC). After optimizing the conditions of ammonia adsorption in the PW. Zeolite addition mitigated ammonia toxicity, allowing zeolites to gradually release ammonia while effectively attenuating algal oxidative stress caused by high TAN concentration. Coupling zeolite-based adsorption and yeast co-incubation further increased TOC degradation and available C/N ratio, thus improving biomass (4.51 g/L), oil yield (2.11 g/L), and nutrient removal (84.18%-99.14%). The integrated microalgae-based PW treatment exhibited higher carbon migration into biomass (46.14%) and reduced treatment costs than conventional approaches. Simultaneously, the lowest carbon migration to wastewater also meant the smallest carbon emission into water bodies. These findings demonstrate that this novel strategy can remove nutrients in raw PW effectively and produce high oil-rich biomass in a sustainable and environmentally-friendly manner.

Cultivation of Spirulina platensis for nutrient removal from piggery wastewater.

The discharge of livestock wastewater without appropriate treatment causes severe harm to the environment and human health. In the pursuit of finding solutions to this problem, the cultivation of microalgae as feedstock for biodiesel and animal feed additive using livestock wastewater coupled with the removal of nutrients from wastewater has become a hot research topic. In this study, the cultivation of Spirulina platensis using piggery wastewater for the production of biomass and the removal of nutrients were studied. The results of single factor experiments confirmed that Cu2+ seriously inhibit the growth of Spirulina platensis, while the influences of nitrogen, phosphorous, and zinc on the growth of Spirulina platensis can all be described as "low promotes high inhibits." Spirulina platensis grew well in the 4-fold dilution of piggery wastewater supplemented with moderate sodium bicarbonate, which indicated that it is the limiting nutrients for Spirulina platensis growth in piggery wastewater. The biomass concentration of Spirulina platensis reached 0.56g/L after 8days of culture at the optimal conditions proposed by the response surface method, which were as follows: 4-fold dilution of piggery wastewater, 7g/L sodium bicarbonate, pH of 10.5, initial OD560 of 0.63, light intensity of 3030lx, and light time/dark time of 16h/8h. Spirulina platensis cultured in the diluted piggery wastewater contained 43.89% protein, 9.4% crude lipid, 6.41mg/g chlorophyll a, 4.18% total sugar, 27.7mg/kg Cu, and 246.2mg/kg Zn. The removal efficiency for TN, TP, COD, Zn, and Cu from the wastewater by Spirulina platensis was 76%, 72%, 93.1%, 93.5%, and 82.5%, respectively. These results demonstrated the feasibility of piggery wastewater treatment by the cultivation of Spirulina platensis.

Enhanced biomethane production with a low carbon footprint via anaerobic co-digestion of swine wastewater with rice husk

An electricity-assisted anaerobic co-digestion (EAAD) process was developed and compared with conventional anaerobic co-digestion (AD) using piggery wastewater and rice husk as feedstocks. Various methodologies, including kinetic models, microbial community analyses, life-cycle carbon footprints, and preliminary economic analysis, were integrated to comprehensively evaluate the performance of the two processes. The results demonstrated that EAAD exhibited a positive improvement of 2.6 % to 14.5 % in biogas production compared to AD. The suitable wastewater-to-husk ratio for EAAD was found to be 3:1, which corresponded to a carbon-to‑nitrogen ratio of approximately 14. This ratio demonstrated positive co-digestion effects and electrical enhancements in the process. According to the modified Gompertz kinetics, the biogas production rate in EAAD ranged from 1.87 to 5.23 mL/g-VS/d, significantly higher than the range of 1.19 to 3.74 mL/g-VS/d observed in AD. The study also investigated the contributions of acetoclastic and hydrogenotrophic methanogens to biomethane formation, revealing that acetoclastic methanogens accounted for 56.6 % ± 0.6 % of the methane production, while hydrogenotrophic methanogens contributed to 43.4 % ± 0.6 %. No significant difference in the methanogenic reaction pathways was observed between AD and EAAD, indicating that the introduction of an external electric field did not alter the predominant pathways (p > 0.05, two-sample t-test). Furthermore, retrofitting existing AD plants with EAAD units can reduce the carbon intensity of piggery wastewater treatment by 17.6 % to 21.7 %. The preliminary economic analysis indicated a benefit-cost ratio of 1.33 for EAAD, confirming the feasibility of implementing EAAD for wastewater treatment while simultaneously producing bioenergy. Overall, this study provides valuable insights into upgrading the performance of existing AD plants by introducing an external electric field. It demonstrates that EAAD can achieve higher and cost-effective biogas production with a lower life-cycle carbon footprint, thus enhancing the sustainability and efficiency of the biogas production process.

Comparison of Dissolved Organic Matter Composition and Microbial Distribution between Distributed-Inflow Biological Reactor and Two-Stage Anoxic/Aerobic for Piggery Wastewater Treatment

Piggery wastewater contains high amounts of feces, carbon, nitrogen, phosphorus, and other contaminants, introducing serious pollution into water, soil, and the atmosphere. Biological treatment technology is widely used in large-scale pig farms because of its high efficiency and economical advantages. In this study, two typical biological treatment systems—a distributed-inflow biological reactor (DBR) and a two-stage anoxic/aerobic (A/O/A/O)—were adopted to treat piggery wastewater to compare the treatment performance, the dissolved organic matter (DOM) composition, and the microbial distribution characteristics. The results show that the A/O/A/O system had better removal performance in terms of chemical oxygen demand (COD) compared to the DBR system, and similarly effective at removing and ammonia nitrogen (NH4+-N) and total nitrogen (TN). Using parallel factor analysis of the fluorescence excitation–emission matrix, four DOM components—namely fulvic acid-like/humic-like substances (C1), tyrosine-like substances (C2), humic-like substances (C3), and tryptophan-like substances (C4)—were tracked in piggery wastewater. Protein-like substances were significantly degraded, while humic-like substances were difficult for microorganisms to utilize. The endogenous input and humus characteristics of effluents were enhanced. Bacteroidetes (43.9% and 37.5% ) and Proteobacteria (43.1% and 56.7%) are the dominant bacteria in DBR and A/O/A/O systems. The microbial metabolites in DBR and A/O/A/O systems are mainly composed of amino acids, sugars, alcohols, and other small molecules, while those in the municipal sewage treatment plant system is mainly composed of ketones, amines, acids, lipids, and other small molecules. The results of microbial communities and metabolites can help to trace the process of biological systems treating piggery wastewater.

Long-term stability of reactor microbiome through bioaugmentation with Alcaligenes aquatilis AS1 promotes nitrogen removal of piggery wastewater

Bioaugmentation is considered as an attractive method for nitrogen removal in water treatment, but its effectiveness in actual high-strength piggery wastewater has not been adequately verified and the mechanism of bioaugmentation in actual wastewater treatment system is not very clear especially from the perspectives of microbial communities and functional genes. This study investigated the mechanisms of a heterotrophic nitrifying-aerobic denitrifying strain Alcaligenes aquatilis AS1 in the bioaugmentation of continuous biological nitrogen removal of actual piggery wastewater at laboratory scale. The addition of strain AS1 significantly improved the nitrogen removal efficiency (more than 95% of NH4+-N and 75% of TN were removed) and raised the activated sludge resistance to shock loading. AS1 addition also significantly shifted the microbiota structure and interactions among microbial networks were enhanced to obtain the stable bacterial communities. Moreover, strain AS1 achieved effective proliferation and long-term colonization in activated sludge with a relative abundance of genus Alcaligenes more than 70% during the whole operation process and played a dominant role in biological nitrogen removal, while different genera were respectively enriched and involved in pollutants removal at different stages in the control group. In addition, the abundances of most functional genes involved in carbon (C) degradation, carbon fixation and nitrogen (N), phosphorus (P), sulfur (S) cycling in activated sludge were significantly increased in reactor AS1, indicating that strain AS1 not only relied on its unique C and N metabolic activities, but also recruited microorganisms with diverse functions to jointly remove pollutants in wastewater, which could be a common bioaugmentation mechanism in open reactors. This study proves the promising application prospect of strain AS1 in the treatment of high-strength piggery wastewater and shows great importance for guiding bioaugmentation application of functional strains in practical wastewater treatment systems.

Exploring the metabolic capabilities of purple phototrophic bacteria during piggery wastewater treatment

Purple phototrophic bacteria (PPB) are receiving an increasing attention due to their extraordinary metabolic capabilities for nutrient and carbon recovery from wastewaters. Batch experiments were herein performed to assess the influence of the type of radiation (photosynthetic active radiation (PAR), near-infrared radiation (NIR) and PAR using an UV-VIS absorbing filter), temperature (13 °C and 30 °C), type of metabolism (photoheterotrophic and chemoheterotrophic), type of inoculum (mixed culture and pure strain Rhodopseudomonas palustris) and wastewater load (1:5 and 1:10 dilutions) during piggery wastewater (PWW) treatment by PPB. The use of UV-VIS filtered PAR supported both a high content of bacteriochlorophyll in PPB and the highest total organic carbon (TOC) and total nitrogen (TN) removal efficiency (RE) (74 % and 37 %, respectively), but at lower maximum removal rates. Interestingly, PPB exhibited similar TOC-REs and TN-REs (73 % and 37 %, respectively) at 13 °C than at 30 °C (71 % and 45 %, respectively), at similar removal rates. Mixed cultures of PPB achieved a higher nutrient assimilation rate than R. palustris, supporting a total assimilation of the volatile fatty acids present in 10 folds diluted PWW. In brief, mixed cultures of PPB were highly efficient during PWW treatment, regardless of the type of radiation and temperature under photoheterotrophic growth.

Extra benefit of microalgae in raw piggery wastewater treatment: pathogen reduction

BackgroundMonitoring microbial communities especially focused on pathogens in newly developed wastewater treatment systems is recommended for public health. Thus, we investigated the microbial community shift in a pilot-scale microalgal treatment system for piggery wastewater.ResultsMicroalgae showed reasonable removal efficiencies for COD and ammonia, resulting in higher transparency of the final effluent. Metagenome and microbial diversity analyses showed that heterotrophic microalgal cultivation barely changed the bacterial community; however, the mixotrophic microalgal cultivation induced a sudden change. In addition, an evaluation of risk groups (RGs) of bacteria showed that raw piggery wastewater included abundant pathogens, and the microalgal treatment of the raw piggery wastewater decreased the RG2 pathogens by 63%. However, co-cultivation of microalgae and the most dominant RG2 pathogen, Oligella, showed no direct effects between them.ConclusionsThus, a microbial interaction network was constructed to elucidate algae-bacteria interrelationships, and the decrease in Oligella was indirectly connected with microalgal growth via Brevundimonas, Sphingopyxis, and Stenotrophomonas. In a validation test, 3 among 4 connecting bacterial strains exhibited inhibition zones against Oligella. Therefore, we showed that microalgal wastewater treatment causes a decrease in RG2 bacteria, which is an indirect impact of microalgae associated with bacteria.Graphical 9xuCqXStUBwsH8dUwtqkoYVideo abstract

Enhancement of swine manure anaerobic digestion using membrane-based NH3 extraction

The influence of suspended solids and pH in anaerobically digested piggery wastewater on membrane-based NH3 extraction was evaluated in batch tests. The increase in pH in the anaerobic broth from 8 to 9 resulted in an increase in NH3 removal efficiencies from 15.8 % ± 0.1 % to 20.9 % ± 0.4 % regardless of the suspended solids. The influence of membrane based NH3 extraction on piggery wastewater treatment was also assessed in a CSTR interconnected with PTFE membrane modules. The decrease in TKN concentrations mediated by membrane operation induced an increase in CH4 yield from 380.4 ± 84.9 up to 566.1 ± 7.8 NmLCH4 g VS fed−1. Likewise, COD and VS removal efficiencies significantly increased from 33.0 % ± 2.0 % and 25.7 % ± 2.3 % up to 61.8 % ± 1.3 % and 37.9 % ± 1.8 %, respectively. Interestingly, the decrease in NH3 concentration entailed a complete assimilation of VFA.

Simultaneous Removal of Nitrate and Tetracycline by an Up-Flow Immobilized Biofilter

The removal of nitrate (NO3−-N) and antibiotics in aquaculture tail water is urgent and necessary. A lab-scale up-flow immobilized biofilter (I-BF) filled with polyurethane foam (PUF) carriers and a microbial consortium was developed for simultaneous removal of nitrate and tetracycline (TC). The denitrification and TC removal performance of the I-BF reactor was investigated under different TC concentrations (0, 10, 50, 100 mg·L−1), carbon/nitrogen (C/N) ratio (2, 4, 5, 6) and hydraulic retention times (HRT) (4, 8, 12 h). Simultaneous removal of nitrogen and TC was achieved by the I-BF reactor. Low TC concentration (≤50 mg·L−1) had little effect on nitrogen removal. The denitrification performance of the I-BF reactor was inhibited at high TC load, which may be attributed to the damage of cell membranes and the inhibition of the intracellular denitrification enzymes’ activities. The optimal C/N ratio and HRT were 5 h and 8 h with almost complete denitrification and high TC removal efficiency (73.46%) at influent NO3−-N and TC concentrations of 100 mg·L−1 and 50 mg·L−1, respectively. The I-BF reactor proposed in this study has promising applications such as the treatment of piggery wastewater, aquaculture tail water and pharmaceutical wastewater co-contaminated with nitrate and antibiotics.