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The moving bed bioreactor (MBBR) process has drawn more attention as a promising biological wastewater treatment process. Nevertheless, achieving quick start-up and microbial biofilm formation remains a significant challenge. Consequently, the present study investigated a novel chitosan-based natural sludge (CS@NGS) seeding strategy for the accelerated start-up of MBBR. Three identical bioreactors were employed; the first bioreactor was without sludge seed as the control (BR1), the second was inoculated only with sludge (BR2), and the third was inoculated with CS@NGS according to the proposed seeding method (BR3). All bioreactors were utilised to treat simulated recirculating aquaculture systems (RAS) effluent. Resultantly, the CS@NGS shortened the start-up period from over twenty to seven days due to the enhanced initial microbial adhesion and biofilm formation. Under optimal conditions, the ammonium removal in BR3 approached 100%, which was relatively higher than BR2 (96.35 ± 1.12%) and BR1 (92.56 ± 2.17%). Moreover, a low nitrite accumulation was exhibited in the effluents, approximately ≤0.03 mg L

Nitrate accumulation is a common phenomenon in aquaculture that can lead to eutrophication of surrounding water bodies. This study used poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as a carbon source and substrate and performed a microbial co-occurrence network ecological analysis to elucidate the denitrification processes in two packed-bed reactors with different salinities. The denitrification rate reached maximum values of 0.438 and 0.446 kg m

Solids removal is very important for water quality maintenance in recirculating aquaculture systems (RAS). Ozonation is a practical water treatment which can promote the solids removal. However, th...

The taste and odor (TO) problem represented by 2-methylisoborneol (2-MIB) and geosmin (GSM) in water is the multiple undesirable substances in the drinking water and the aquatic industry. In this study, the UV-assisted photoelectrochemical, a prospective advanced oxidation process (AOP), was evaluated for the degradation of 2-MIB and GSM. In contrast to UV photochemical and electrochemical, the degradation ratio of GSM (2-MIB) increase to 96% (95%) in 25 min. The removal ratio and rate depended on reaction time, electrolyte concentration, current density, and water quality parameters (e.g. pH, HCO

In this study, a novel sponge biocarriers (SB) in moving bed bioreactor (MBBR) treating recirculating aquaculture systems wastewater was evaluated for the first time. Two lab-scale MBBRs were operated simultaneously for 116 days under various hydraulic retention times (HRTs). The reactors R1 and R2 were filled with K5 plastic carriers and SB, respectively. From the results, at an optimum HRT of 6 h, ammonia removal efficiency and nitrification rate were 86.67 ± 2.4% and 1.43 mg/L.h for the R1 and, 91.65 ± 1.3% and 1.52 mg/L.h for the R2, respectively. The microbial community analysis showed that the predominant genera in the nitrifying community were Nitrosomonas (AOB) and Nitrospira (NOB) in co-existence with heterotrophic genera Hyphomicrobium, Mesorhizobium, Zhizhongheella, and Klebsiella spp. Modified Stover-Kincannon model examined the ammonia removal kinetics, and the values of kinetic parameters obtained were Umax: 0.909 and 1.111 g/L.d and KB: 0.929 and, 1.108 g/L.d for the R1 and R2, respectively. The correlation coefficients (R2) of the MBBRs were higher than 0.98, indicating that the model adequately described the experimental data. Overall, MBBR, filled with the proposed novel SB operated at 6 h HRT, can achieve the highest nitrification performance and increase the diversity of the functional microbial communities.

Pond aquaculture plays a major role in world aquaculture production, especially in China. To make pond aquaculture more precise, ecologically sound, and efficient, in this study, an intensive pond aquaculture system (IPAS) was designed and built to produce freshwater fish that are commonly reared in China. Aquatic plants and filter-feeding, omnivorous fish were used to rehabilitate the aquaculture water quality, and the particle size distribution (PSD) model of suspended solids in the pond raceways was investigated. The results showed that the water quality in the purification pond was improved compared to that in the sedimentation basins, and it was close to the water quality in the raceways, which were within the acceptable range. The number distribution of suspended solids can be described by the power law model (R2 = 0.901 ± 0.032), which can provide guidance for solids removal using different methods. Moreover, during one production cycle, economic benefits of the IPAS were also evaluated; the return on investment (ROI) of 35.69% and benefit cost ratio (BCR) of 1.36 indicated that this kind of aquaculture mode has achieved a better profit. There are many fish species in China, so developing an IPAS with a wide application range requires further study in the future. Keywords: Airlift push-water aerator, Aquatic plant, Drum filter, Intensive pond aquaculture system, Particle size distribution, Purification pond.

This research investigated two proposed modified biofilm carriers' performances in treating recirculating aquaculture systems (RAS) wastewater under different salinities (12‰, 26‰, and 35‰) for about 92 days. Three moving bed biofilm reactors (MBBRs; R1, R2, and R3) were filled with unmodified novel sponge biocarriers (SB) served as a control, modified novel SB with ferrous oxalate (C2FeO4@SB), and modified novel SB with combined ferrous oxalate and activated carbon (C2FeO4-AC@SB), respectively. Under the highest saline condition, a significantly higher ammonia removal efficiency of 98.86 ± 0.7% (p ˃ 0.05) was obtained in R3, whereas R2 and R1 yielded 95.18 ± 2.8% and 91.66 ± 1.5%, respectively. Microbial analysis showed that Vibrio, Ruegeria, Formosa, Thalassospira, and Denitromonas were predominant genera, strictly halophilic heterotrophic nitrifying bacteria involved in nitrogen removal. In conclusion, the synergistic effects of novel sponge, C2FeO4 and AC accelerated biofilm formations and stability, subsequently enhanced the removal of ammonia from the mariculture RAS wastewater by the C2FeO4-AC@SB carriers in R3.

To identify the performance of step-fed submerged membrane sequencing batch reactor (SMSBR) treating swine biogas digestion slurry and to explore the correlation between microbial metabolites and membrane fouling within this novel reactor, a lab-scale step-fed SMSBR was operated under nitrogen loading rate of 0.026, 0.052 and 0.062 g NH

This study investigated the relation between 17β-estradiol (E2) degradation and nitrification in synthetic mariculture wastewater by ammonia oxidizing bacterium Nitrosomonas europaea and moving bed biofilm reactor (MBBR). Batch experiments showed that E2 degradation by N. europaea in wastewater followed zero-order reaction kinetics (r2 = 0.944, 4.07 μg/ L h−1) when ammonia presented. Nitrite yield in N. europaea inoculation decreased by 77.8% exposed to 1 mg/L E2. The inhibitory impact on ammonia oxidation was enhanced with increasing E2 dosage from 50 ng/L to 1 mg/L. Notably, E2 as low as 50 ng/L still had significant interference with nitrite production, bacterial density and ammonia monooxygenase (AMO) activity of N. europaea. Still, the following continuous 68-day degradation test revealed that 84.5%–98.7% E2 could be removed by a bench-scale MBBR. Whereas, ammonia removal remarkably decreased from 94.7% ± 2.1% to 85.6% ± 2.1% (p

This study proposed two novel Combined Denitrification and Biofloc Technology (CDBFT) systems (one under blue LED light (L1) and the other without light (C1), each containing a denitrification (DE) reactor and a biofloc-based reactor) for the enhanced total nitrogen (TN) removal. Long-term operation (110 days) suggested that simultaneous nitrification and denitrification was achieved in both C1 and L1. Significantly higher total nitrogen removal efficiency (TNRE) was observed in L1-CDBFT (92.2%) than C1-CDBFT (87.5%, P < 0.05; after day 14). Further 24-hour nitrogen transformation test showed the boosted nitrate removal of L1-BFT than C1-BFT. High-throughput sequencing analysis revealed that phyla Rotifera and Nematoda which were indispensable for aquatic animal larviculture, were only found in L1-BFT. Nevertheless, CDBFT effluent from both systems was suitable for tilapia culture based on water quality, biofloc characteristics and tilapia survival rates. Overall, this study highlights the significance of developing CDBFT for TN removal especially under lights.

Inorganic‑nitrogen removal is essential for the sustainable operation of aquaculture industry and also influences the health of aquatic animals, which may be accomplished by utilizing biofloc technology. In this paper, we studied the use of three different carbon sources 1) longan seed powder (LP), 2) Poly(β-hydroxybutyrate-β-hydroxyvalerate) (PHBV) and 3) synthesized PHBV and LP (PHBVL) in biofloc systems for 90 days to investigate the nitrogen dynamics and gut microbiota of Nile tilapia (Oreochromis niloticus). The PHBVL and PHBV groups had higher total inorganic‑nitrogen removal efficiencies (70.99 ± 19.45% and 63.54 ± 19.44%) than the LP group (35.02 ± 11.21%), which had an accumulation of nitrate. Meanwhile, the biofloc in PHBVL and PHBV group generally had a higher amino acid composition, particularly for methionine and lysine, but was not reflected in the tilapia muscle. High-throughput sequencing indicated that the different carbohydrates shaped different bacterial community compositions in the fish gut after exposure in the three environments for 90-day. These differences, which resulted in different gut digestive enzyme activities (amylase, lipase and trypsin), and growth performance, which the food conversion ratio in the PHBVL group was lower than LP and PHBV group, the final body weight in PHBVL group was average 4.33% and 3.65% bigger than in LP and PHBV group. Network analysis revealed that the keystone taxa (90.33%) were Proteobacteria, Chloroflexi, Actinobacteria, Planctomycetes, Verrucomicrobia and Bacteroidetes, which relative abundance varied in the fish gut in the three groups. The experiment verified the feasibility and advantage to use biodegradable polymers (BDPs) as carbohydrates for biofloc systems.

In this study, an airlift inner-loop sequencing batch reactor using poly(butylene succinate) as the biofilm carrier and carbon source was operated under an alternant aerobic/anoxic strategy for nitrogen removal in recirculating aquaculture system. The average TAN and nitrate removal rates of 47.35±15.62gNH4-Nm(-3)d(-1) and 0.64±0.14kgNO3-Nm(-3)d(-1) were achieved with no obvious nitrite accumulation (0.70±0.76mg/L) and the dissolved organic carbon in effluents was maintained at 148.38±39.06mg/L. Besides, the activities of dissimilatory nitrate reduction to ammonium and sulfate reduction activities were successfully inhibited. The proteome KEGG analysis illustrated that ammonia might be removed through heterotrophic nitrification, while the activities of nitrate and nitrite reductases were enhanced through aeration treatment. The microbial community analysis revealed that denitrifiers of Azoarcus and Simplicispira occupied the dominate abundance which accounted for the high nitrate removal performance. Overall, this study broadened our understanding of simultaneous nitrification and denitrification using biodegradable material as biofilm carrier.

Struvite precipitation may become ineffective in removing phosphorus due to the low concentration of phosphate in the liquid. In this study, electrolysis with a magnesium anode was applied to recovering phosphorus and ammonia as struvite from wastewater. A novel electrodialysis process (ED) with a magnesium anode was developed, and its feasibility to treat synthetic wastewater with low phosphate concentration was demonstrated in a pilot-scale experimental system. To achieve high phosphate removal efficiency in the product stream, the optimal initial pH and flow rate were found to be 8.8 and 200 L h−1, respectively, for the ED system at a constant current of 0.1 A. The pilot-scale ED system under the consecutive batch mode removed 65% phosphate from the synthetic wastewater containning 10 mg L-1P, and the phosphate concentration in the product stream was kept at 30 mg L−1 after 280 min. The running cost of the ED system was estimated to be $31.27 kg−1 P for synthetic wastewater with 10 mg L−1 P, mainly resulting from the cost of the loss of the magnesium anode. The precipitates generated from the product stream were confirmed as struvite by XRD analysis.

Mariculture wastewater treatment by nitrification requires a long start-up time due to high salinity stress. This study aimed to verify the faster start-up of a trickling filter (TF) compared to a moving bed bioreactor (MBBR) treating synthetic mariculture wastewater, and to investigate the feasibility of transferring mature biocarriers from the TF to a new MBBR (TF-MBBR). The nitrogen removal performance, biofilm physicochemical properties and microbial communities were investigated. The results obtained showed that, the TF started up 41 days faster than the MBBR, despite the richer microbial diversity in the latter. Lower biofilm roughness and protein content as well as higher adhesive force and polysaccharide content in the TF were obtained compared to the MBBR. Adhesive force was found to be negatively correlated with roughness (r = −0.630, p = 0.069). Transmittance assigned to amide II (1538 cm−1) and amid III (1243 cm−1) through Fourier transform infrared spectroscopy (FTIR) determination was only obtained in the TF, which was likely related to the faster start-up. Nitrosomonas and Nitrospira were detected as the predominant nitrifiers in both reactors. In addition, the new MBBR, incubated with the mature biocarriers transferred from the TF, had a satisfactory nitrification performance with no lag time. Interestingly, the transfer action increased the microbial diversity and made the biofilm physicochemical characteristics shift toward those of the MBBR. Taken together, the study confirmed that MBBR nitrification start-up can be accelerated via TF and biocarrier transfer.

The objective of this study was to investigate the inactivation efficacy of slightly acidic electrolyzed water (SAEW, pH 6.31-6.85) in the process of raw frozen shrimp handling and postharvest preservation. The experiment was carried out in the processing workshop of raw frozen shrimp of Zhejiang Yueteng Aquatic Food Co., Ltd., Hangzhou, China. The inactivation effect of SAEW in the process of raw frozen shrimp was considered on the side of raw shrimp, gloves as well as contact surfaces. Shrimp samples were treated with SAEW (29 or 16 mg L-1 of available chlorine) for 3 or 5 min under spraying conditions, meanwhile, gloves and contacting surfaces were treated with SAEW. The quality of raw frozen shrimp in the duration of storage was observed for 11 days. The bacteria count was reduced by 0.21~0.72 log units after the treatment of SAEW. The effect of SAEW on gloves was better than that of alcohol (P sodium hypochlorite solution on contact surfaces in bactericidal activity. Finally, the survival total bacteria and coliforms of shrimp were effectively controlled in storage, and there was no significant change (P > 0.05) on the pH values and residual chlorine of shrimp meat. This study suggests that SAEW treatment can be a way to effectively control bacteria on shrimp processing environment and to improve the quality of shrimp during storage.

In large livestock houses, controlling the internal environmental condition is a key factor for enhancing livestock productivity. The basis of thermal comfort, contaminants, and ventilation efficiency is the internal air flow, which can be controlled by the ventilation system. Field experimentation is a challenging method for analysing air flows due to limited number of measurement points, cost, unstable weather conditions, and experimental errors. Alternatively, computational fluid dynamics (CFD) have been extensively used to overcome the limitations of field experiments by means of their ability to artificially control experimental conditions and the ease with which structural configurations are modified. Most of the previous CFD simulations have regarded livestock structures as two-dimensional or simplified three-dimensional domains and complicated configurations that include animals have been ignored in simulation models. However, the presence of animals in commercial livestock buildings can significantly influence air flow patterns and internal environmental conditions. In this study, a full-scale commercial pig house was modelled to investigate the ventilation problems during the cold season. The simulation of pigs, and specific configurations of the ventilation system, was considered to improve the reliability of the CFD model. The CFD computed air temperature showed a −4.4% error compared to the field experimental data and this model was used to enhance the internal environmental conditions in the existing pig house by changing ventilation designs by sealing the entrances and reducing the size of inlet area, resulting in 24% improved thermal uniformity.

Two identical pig rooms, with mechanical ventilation, were used to compare the environmental impact of a deep litter fermentation system for growing-finishing pigs with a fully slatted floor system. The pig manure in the fully slatted floor room was removed manually twice daily, but in the fermented deep litter room, no manure was removed. Indoor and outdoor temperature, relative humidity, and ammonia concentration were measured continuously during the whole experimental period. Odour was sampled and analysed using the triangle odour bag method for 15 days during the experimental period. The performance of the pigs was not significantly different between the floor types. There were significant differences for both NH3 concentrations and emissions according to floor type (p It was concluded that the deep litter fermentation system for pig production shows advantages in reductions of ammonia and odour.

In this paper, aerobic biological filter is applied to treat swine farms wastewater. Laboratory experiments are conducted to confirm the optimum parameters for start-up and operation of filter by investigating the effect of temperature on the start-up of the filter and the influence of temperature, pH value and recirculation rate on the treatment effect of the filter. The results show temperature increasing is benefit for accelerating start-up of filter in the range of 17.0-33.0°C. COD removal of the filter enhances slightly by temperature rising during normal operation. High NH3-N reduction (above 84.0%) is obtained in range of 25.0-30.0°C. pH in range of 7.1-8.0 is recommended for operation treatment, in which pollutants reduction for COD and NH3-N is 85.7%-86.9 and 86.8%-89.5%, respectively. COD and NH3-N reduction enhances with recirculation rate increasing. When the recirculation rate is above 4, the increasing of COD and NH3-N reduction is slight. Swine wastewater treatment project utilizing aerobic biological filter as a key element is established in a swine breeding farm of Daxing district, Beijing. The whole project runs well by start-up and operation of filter. COD reduction of wastewater in aerobic biological filter is 63.0-89.3%. And the COD concentration of effluent in filter is below 150 mg/L, which achieves the national requirement of pollutants output standard of livestock and poultry breeding industry and water quality standard of farmland irrigation. The aerobic biological filter is worth to be generalized for treating swine wastewater in China.

Gaseous pollutants in broiler house may cause negative effects to the production performance and health of broilers. Ventilation is an effective and simple way to improve air quality in broiler house. For the purpose of heat preservation, there is little ventilation in broiler house in winter season for small-scale broiler production in China, which leads to serious air quality issues. This paper proposes an optimization of a local ventilation system which could be used for gaseous pollutants removal in winter.

The reaction pathways of co-liquefaction of swine manure and crude glycerol to bio-oil (ester compounds) were investigated. Swine manure was hydrothermal treated (340 °C, 27.5 MPa, 15 min) with a number of model compounds in a high pressure batch reactor under inert atmosphere. The compounds were methanol, pure glycerol, mixture of pure glycerol, pure methanol and H 2 O, and commercial fatty acids (linoleic acid). The chemical composition of the bio-oil was analyzed by GC/MS. Glycerol, methanol and water showed synergistic effects on manure liquefaction, increasing the oil yield as high as 65%. A maximum oil yield of 79.96% was obtained when linoleic acid reacted with swine manure. Based on the results, the reaction pathways were proposed. Esterification reactions occurred not only because the crude glycerol have methanol, but also because methanol can be produced from hydrothermal reactions of glycerol.

The main source of ammonia and odour from most livestock buildings is the slurry pit. The ammonia emission rate is affected by the air exchange rate in the slurry pit. Reduction of air exchange between slurry pit and room air may reduce the emissions. The hypothesis that using an environmental deflector in the room and curtains in the slurry pit may affect air exchange rate between the slurry pit and the room air was validated. In the experiment, three position angles for the deflector and three arrangements of curtains were investigated in a two-dimensional ventilation chamber under isothermal conditions at two ventilation airflow rates. The airflow pattern, air velocity and turbulence intensity inside the chamber were also recorded. The results showed that the airflow patterns, air velocities and turbulence intensities in the room space near the slatted floor and in the headspace of the pit were influenced by changing deflector angles and curtain numbers. It was found that the lowest pit ventilation and the highest concentration in the headspace of the pit could be achieved by using a deflector's position angle of 45° at both of two airflow rates. On the other hand, it was also found that more curtain numbers under the slatted floor and lower room ventilation rate caused lowest pit air exchange rate and the highest concentration in the headspace of pit.

The effect of nine factors - ventilation flow, floor system, headspace height in pit, slurry pit curtain, slurry temperature, pit temperature, room temperature, outdoor temperature, and room relative humidity - on ammonia (NH 3 ) emissions from the pig rooms was evaluated. The five parameters that explained most of the variability of the NH 3 emissions from the pig room were ventilation rate, floor system, slurry temperature, headspace height in pit, and slurry pit curtain. NH 3 emission rate increased as room ventilation rate increased with diffuse ceiling inlet. However, the lower slurry temperature could reduce NH 3 emission or compensate the effects of higher ventilation rate. Increasing surface area of slurry and the floor opening area increases the air exchange rate in slurry pit, thus causing greater NH 3 emission rate. The reduction of NH 3 emission rates could be achieved by 67.4%, 45.5% and 50.8% (average in four ventilation rates) at headspace heights of 0.75 m, 0.50 m and 0.25 m using floor system in pig room A compared with floor system in pig room B, respectively. There was poor correlation between NH 3 emission rate and headspace height in pit. It was found that the NH 3 emission rates for all four ventilation rates with curtains were significantly lower than without curtains only at the 0.50 m headspace height. Mean reductions of 1.7%, 20.1% and 13.7% in NH 3 emission could be achieved by using pit curtains compared to without curtains at 0.75 m, 0.50 m and 0.25 m headspace heights, respectively, averaged over four ventilation rates.