Fish Effluent Research Articles

Integration of Biochar Filtration into Aquaponics: Effects on Particle Size Distribution and Turbidity Removal

Small- and large-scale biochar-based filtrations were conducted to investigate the potential of biochar as a low-cost renewable filtration medium in aquaponics. The small-scale experimental design investigated the effects of 2 biochar media sizes (1 – 3 mm [referred to as fine biochar] and 3 – 5 mm [referred to as coarse biochar]), 3 biochar bed heights (2.5, 5.0 and 10.0 cm) and 3 loading rates (5, 10 and 15 m3/m2/d) on particle size distribution as well as turbidity removal efficiency. Both biochar sizes (fine and coarse) were able to clarify fish effluent. However, fine biochar led to better filtration characteristics compared to coarse biochar. Results indicated that biochar filter bed heights and loading rates affected the filtration performances. Using deeper filters combined with lower loading rates led to greater removal of suspended particles and turbidity compared to shallower filters and/or higher loading rates. Results from the large-scale filtration, using a mixture of fine and coarse biochar media (size of 1 – 5 mm), revealed that the ideal loading rate for maximizing the removal of turbidity from fish effluent in high-intensity aquaponic system for production of Nile tilapia and greenhouse plants (with 80 m3 total volume of water, 40 kg/m3 average stocking density and 15 kg/d feeding rate) was 10 m3/m2/d. This study suggests that biochar-based filtration could be incorporated into aquaponics as a polishing step before sending the water to plant growth systems.

Effect of organic soil amendments on soil quality in oil palm production

Soil quality (SQ) evaluation is an essential tool for the enhancement of agricultural soil management and use. An array of soil attributes, termed soil quality indicators, are used in soil quality estimation due to their sensitivity to disturbance from management practices. Therefore, the objective of this study was to assess the soil quality (using multivariate ordination technique) of oil palm (Elaeis guineensis, Jacq.) plantations amended with on-farm biomass. The experimental sites were three oil palm plantations located in the southernmost Pattani province of Thailand namely, Ban Chamao (BC), Ban Lipasango (BL) and Ban Bothong (BB) fertilised with fish effluent (FE), empty fruit bunch (EFB) compost and NPK (plus EFB mulch), respectively with completely randomised block design. A minimum dataset (MDS) of soil indicators were defined using multivariate principal component analysis (PCA). The selected MDS comprised mainly geometric mean of microbial enzyme activity (GME), available phosphorus (AP) and moisture content (MC) with per cent contribution towards soil quality index (SQI) (assessed based on PCA after scoring by normalised linear function) in the order: GME (77.3%) > AP (13.6%) > MC (9.1%). Essentially, the activity of enzymes is a crucial ecosystem function (nutrient cycling), further indicating that decreases in soil enzyme activities can be signal for a decline in SQ. GME, AP, and MC effectively differentiated the oil palm plantations and could be important not only in monitoring soil quality enhancement in the present study locations but also in a similar tropical environment with similar edaphic conditions. SQI was not significantly different between the BB (0.81) and BL (0.79) plantations (p = 0.46). However, both BB and BL were higher than in BC (0.65). BB and BL showed low geometric mean of microbial biomass GMB, high soil pH, C, N, GME and qCO2 (metabolic quotient, i.e., the amount of CO2 respired per unit microbial biomass), while the fish effluent amended BC plantation showed the opposite. EFB contains a substantial quantity of nutrients and organic matter (OM) capable of reducing soil acidity, stimulating enzyme activity, and enriching the soil with nutrients with the resultant improvement in SQ. Therefore, a regular practice of returning EFB (either as compost or mulch, with or without mineral NPK) to the soil should be encouraged for smallholder oil palm plantations to improve soil quality and serves as an alternative channel for on-farm biomass disposal.

Aquatic bacterial contamination associated with sugarplant sewage outfalls as a microbial hazard for fish

The aim of the study was to compare bacterial composition and load in waters and fish related to the wastewater treatment plant (WWTP), particularly waters and wild fish affected by sugarplant processing (sugar cane and sugar beet). Aeromonads were the most frequently isolated group from water and fish. A. hydrophila was a prevailing species in isolates from water, followed by A. veronii, Rheinheimera soli and Ochrobactrum anthropi. Of indicator bacteria for aquatic contamination from fish tissues, the most prominent were V. cholerae, Enterobacter cloacae and E. sakazakii. Sugar cane processing contributed to high viable cell counts at 37 °C while sugar beet processing contributed to high bacterial counts at 22 °C. Heterotrophs from gills of effluent fish were highest during sugar cane processing. Counts retrieved from fish skin were more uniform between effluent fish and fish from downstream waters. Antimicrobial resistance of bacteria isolated from water was high against amoxicillin, sulfamethoxazole, flumequine, norfloxacin and oxolinic acid in samples from the inflow of raw municipal wastewaters to WWTP, while resistance found in bacteria from the inflow of sugarplant mostly related to sulfamethoxazole and amoxicillin. The PCA analysis associated the occurrence of high heterotroph counts, P. aeruginosa, and intestinal enterococci on skin and gills with sugar cane, and yeasts and molds with sugar beet processing. Fish living in treated wastewaters and related water bodies could pose a microbial hazard if fished for human consumption, possibly causing infection when being handled and processed, as a risk of human pathogens penetrating fish tissues.

Evapotranspiration of cherry tomatoes under drip irrigation with fish effluent in hydroponic system

Cherry tomatoes have been introduced as one of the main nutritious greenhouse products, valuable source of vitamin and most widely consumed staple food. The integration of aquaculture with agriculture appears to be an excellent way of saving water, disposing aquaculture effluents and providing additional fertilizer to the crop. It is necessary to optimize irrigation water requirement by estimating crop evapotranspiration correctly enough to avoid wastage of water. The aim of this study was to determine the evapotranspiration of cherry tomatoes ('Sweet million') under drip irrigation with fish effluent in hydroponic system. The greenhouse experiment was carried out in a split-plot design with three irrigation water qualities (well water with nutritious solution, fish effluent with nutrients and fish effluent without any nutrients), four media (perlite 100%, perlite 40%-cocopeat 60%, perlite 60%-cocopeat 40%, and soil) in four replications at Bajgah, College of Agriculture, Shiraz University. The reference evapotranspiration (ETO) was calculated by using FAO Penman-Monteith method. The meteorological data was recorded inside the greenhouse every day. The crop evapotranspiration (ETC) was determined using water balance method and compared with the dual crop coefficient method. The highest and lowest cherry tomatoes' productivity was in soil (0.755 kg plant-1) and perlite (0.181 kg plant-1). The seasonal ETO was 570 mm and the lowest and the highest of ETO were 1.53 mm d-1 (July) and 4.44 mm d-1 (October) respectively. The ETC were 613.14 mm (balance method) and 569.94 (dual crop), respectively, in soil culture. Results revealed that the ETC was underestimated 8%. The calculated ETC was lower in other media than soil.

INTEGRATED MANAGEMENT OF FISH (NILE TILAPIA) AND LEAF VEGETABLE CROP (HEAD LETTUCE) CULTURE UNDER DRIP IRRIGATION SYSTEM

Effluent of fish farms is considered a safe source for irrigation and fertigation in the same time. A field experiment took place on Horticulture research farm, Faculty of Agricultural, Kafr El-Sheikh University, north of the Nile Delta, Egypt, having a clay textured soil during winter growing seasons of 2015/2016 and 2016/2017to study the effect of utilization of fish effluent on lettuce production and emitters performance under drip irrigation system. The drip irrigation system was studied at three different emitter types: long path flow, in-line type and 4 l h-1 discharge (D1); turbulent flow, on-line type and 6 l h-1 discharge (D2) and laminar flow, on-line type and 4 l h-1 discharge (D3), three levels of recommended N dose: 100% N, 75% N and 50% N and two different sources of irrigation water: traditional irrigation water (IW) and drainage water of fish ponds (FW). Traditional irrigation water was applied at 100% N only. Main results cleared out that, FW increased clogging ratio comparing with IW for different emitter types, D3 emitter had the highest clogging ratio while D2 emitter had the lowest; application uniformity at end of the growing season decreased comparing with it at beginning for all treatments, FW decreased Cu at end of the growing season comparing with IW; FW enhanced lettuce yield comparing with IW for different treatment, where FW increased total head yield by 51.2, 50.2 and 61.3% for D1, D2 and D3 respectively comparing with IW under 100% N level; FW increased water and nitrogen productivity comparing with IW for different treatments. Weight gain during feed period values were 52.95 and 52.42 g at the technique of water exchange and traditional treatment respectively.

Growth and quality of Handroanthus impetiginosus (Mart. ex DC.) Mattos seedlings irrigated with saline fish effluent

Growth and quality of Handroanthus impetiginosus (Mart. ex DC.) Mattos seedlings irrigated with saline fish effluent

Integrated production of fish (pacu Piaractus mesopotamicus and red tilapia Oreochromis sp.) with two varieties of garnish (scallion and parsley) in aquaponics system

Aquaponics is emerging as an alternative for high-health food production. Being able to identify the technical viability of non-conventional plants and fish species would help to increase the interest and possibilities in aquaponic systems. The goal of the present study was to evaluate the aquaponics production of two garnish species: scallion (S) and parsley (P), using effluents of pacu and red tilapia culture. Two aquaponics devices were used, differing according to the fish species, generating two different effluents. Thus, for plant performance, four treatments were evaluated in a factorial design (plant species and fish effluent as main factors), as followed: Pacu-S, Tilapia-S, Pacu-P, and Tilapia-P, with three replicates each, for 35 days. Fish performance was evaluated using Student’s t test. Each experimental device included a fish tank, filters, and six experimental units for the plants (floating rafts). Results indicated that feed conversion ratio (FCR) was higher in tilapia as compared to pacu (p 0.05), except for higher number of leaves per plant in scallion cultured using pacu effluent. Plant performance comparing both plant species indicated that scallion performed better as compared to parsley in all parameters. In addition, scallion also performed better related to the plant quality index. The results indicate that pacu presented a viable alternative for the aquaponics production, and regarding to the garnish, scallion performed better results as compared to parsley.

Impact of treated wastewater on organismic biosensors at various levels of biological organization

Relating the treated wastewater quality and its impact on organismic biosensors (Prussian carp, Carassius gibelio and earthworm, Eisenia fetida) was the main objective of the study. The impact on health status of fish living downstream, microbiological contamination and antimicrobial resistance, fish tissue structure, blood biochemistry, oxidative stress, genotoxic effects, as well as multixenobiotic resistance mechanism (MXR) was assessed. Treated wastewater discharged from the WWTP modified the environmental parameters and xenobiotic concentrations of the receiving surface waters. Potential bacterial pathogens from fish and respective waters were found in relatively low numbers, although they comprised aeromonads with a zoonotic potential. High resistance profiles were determined towards the tested antimicrobial compounds, mostly sulfamethoxazole and erythromycin. Histopathology primarily revealed gill lamellar fusion and reduction of interlamellar spaces of effluent fish. A significant increase in plasma values of urea, total proteins, albumins and triglycerides and a significant decrease in the activity of plasma superoxide dismutase were noted in carp from the effluent-receiving canal. Micronucleus test did not reveal significant differences between the examined groups, but a higher frequency of erythrocyte nuclear abnormalities was found in fish sampled from the effluent-receiving canal. Earthworms indicated to the presence of MXR inhibitors in water and sludge samples, thus proving as a sensitive sentinel organism for environmental pollutants. The integrative approach of this study could serve as a guiding principle in conducting evaluations of the aquatic habitat health in complex bio-monitoring studies.

Utilization of effluent fish farms in tomato cultivation

Abstract The main objective of this research is to study to which extent the content of nutrients in water farming is sufficient for growing tomato plants. The obtained results indicated that the nutrients consumption increased with increasing the flow rate. The root and shoot length increased with increasing effluent flow rate, when the effluent flow rate increased from 4.0 to 6.0 L h−1, the length of root and shoot significantly increased from 50.33 to 55.33 and 149.33 to 191.33 cm, respectively, at the end of growing period. The fresh and dry mass of shoot significantly increased from 998.01 to 1372.10 and 83.71 to 275.09 g plant−1, respectively, with increasing flow rate from 4.0 to 6.0 L h−1. The fresh and dry mass of root significantly increased from 388.07 to 423.91 and 30.37 to 38.98 g plant−1, respectively, with increasing flow rate from 4.0 to 6.0 L h−1. The fruit yield significantly increased from 1.06 to 1.37 kg plant−1 with increasing flow rate from 4.0 to 6.0 L h−1. The fruit mass and number of fruits increased from 75.07 to 81.32 g and 14.12 to 16.85 with increasing flow rate from 4.0 to 6.0 L h−1. The water use efficiency increased from 5.54 to 7.16 kg m−3 with increasing flow rate from 4.0 to 6.0 L h−1. Using the effluent fish farm could save fertilizers which equivalents 0.13 LE kg−1 fruits (130 LE t−1 fruits). Besides it is considered as an organic product which is safe for the human health.

UTILIZATION OF EFFELUENT FISH FARMS IN TOMATO CULTIVATION

The main objective of this research is to study to which extent the content of nutrients in water farming is sufficient for growing tomato plants. The obtained results indicated that the nutrients consumption increased with increasing the flow rate. The root and shoot length increased with increasing effluent flow rate, when the effluent flow rate increased from 4.0 to 6.0 L h-1, the length of root and shoot significantly increased from 50.33 to 55.33 and 149.33 to 191.33 cm, respectively, at the end of growing period. The fresh and dry mass of shoot significantly increased from 998.01 to 1372.10 and 83.71 to 275.09 g plant-1, respectively, with increasing flow rate from 4.0 to 6.0 L h-1. The fresh and dry mass of root significantly increased from 388.07 to 423.91 and 30.37 to 38.98 g plant-1, respectively, with increasing flow rate from 4.0 to 6.0 L h-1. The fruit yield significantly increased from 1.06 to 1.37 kg plant-1 with increasing flow rate from 4.0 to 6.0 L h-1. The fruit mass and number of fruits increased from 75.07 to 81.32 g and 14.12 to 16.85 with increasing flow rate from 4.0 to 6.0 L h-1. The water use efficiency increased from 5.54 to 7.16 kg m-3 with increasing flow rate from 4.0 to 6.0 L h-1. Using the effluent fish farm could save fertilizers which equivalents 0.13 LE/kg fruits (130 LE/ton fruits). Besides it is considered as an organic product which is safe for the human health.

Azospirillum brasilense Enhances Recycling of Fish Effluent to Support Growth of Tomato Seedlings

Increasing environmental concerns and growing demand for safer and sustainable food production presents significant challenges for agricultural production. One potential technique, which could help improve crop productivity without adverse impact on the environment, is the use of beneficial microbes in crop production systems. This study evaluated the effects of three Azospirillum brasilense strains on tomato seedlings fertilized with effluent from freshwater fish aquaculture. Seeds were inoculated with A. brasilense strains Sp7, Sp7-S and Sp245 before sowing and after transplanting. Seedlings were raised under controlled greenhouse conditions with natural light. Inoculated seedlings produced longer roots (67%), bigger leaves (22%), higher seedling biomass (>33%), and greater protein (15%) and endogenous plant IAA (94%) contents. Inoculation with Sp7 and Sp245 increased the number of leaves and stem diameter by 8 and 10%, respectively. Seedling height was also increased by inoculation, but only with Sp7. In addition, seedlings inoculated with strains Sp7-S and Sp245 had higher total phosphorus content, while inoculation with Sp245 increased the activity of the enzyme peroxidase, which suggests that plant defense responses had been triggered. The result demonstrates the potential of the applied A. brasilense strains to enhance the usefulness of fish effluent as fertilizer for tomato seedling production.

Response of Cucumber Seedlings Fertilized with Fish Effluent to Azospirillum brasilense

ABSTRACTAn emphasis on reducing use of agrochemicals and recycling organic waste to alleviate pollution and nutrient discharge to the environment has prompted exploration of beneficial microbes and aquaculture wastewater in agriculture production. A study was conducted to investigate effects of strains Sp7, Sp7-S, and Sp245 of Azospirillum brasilense on cucumber (Cucumis sativus L.) seedlings fertilized with fish effluent. Cucumber seed were inoculated prior to germination and transplanting. Seedlings were grown in a greenhouse with natural light. Inoculated seedlings produced longer roots, greater root biomass, and higher total phosphorus, endogenous plant indole-3-acetic acid, and peroxidase activities. Inoculation caused small changes in the fish effluent bacterial community, indicating that these strains can be integrated into a production system utilizing fish effluent as a fertilizer. A. brasilense could be a valuable agent to help maximize the usefulness of aquaculture wastewater to support plant growth.

Fish effluents promote root growth and suppress fungal diseases in tomato transplants

Gravel, V., Dorais, M., Dey, D. and Vandenberg, G. 2015. Fish effluents promote root growth and suppress fungal diseases in tomato transplants. Can. J. Plant Sci. 95: 427-436. Aquaculture systems generate large amounts of wastes which may constitute a beneficial amendment for horticultural crop in terms of nutrients, plant growth promoter and disease suppressiveness. This study aimed to determine (1) the nutrient value of rainbow trout farming effluents coming from two feed regimes and (2) the plant growth and disease suppressiveness effects of those fish farming effluents on tomato transplants. The effluent sludge from Skretting Orient™ (SO) had a higher content of P (38 vs. 32 mg L-1), K (23 vs. 11 mg L-1), N (19 vs. to 11 mg NO3 L-1; 186 vs. 123 mg NH4 L-1), and a higher NO3:NH4 ratio (1:9 vs. 1:13) compared with the Martin Classic (MC), while MC was richer in Mg (42 vs. 24 mg L-1) and Ca (217 vs. 169 mg L-1). For the first trial, a stimulating effect of the fish effluent was observed on plant height, leaf area and root dry biomass, while only the root biomass was increased during the second trial. Fish sludge was rich in microorganisms (97 and 142 µg fluorescein h-1 mL-1 for SO and MC, respectively) and their ability to suppress Pythium ultimum Trow and Fusarium oxysporum f.sp. lycopersici (Sacc.) Snyder & Hansen was observed. Both crude fish effluents reduced in vitro mycelial growth of P. ultimum and F. oxysporum, by 100 and 32%, respectively, while MC effluents showed a higher inhibition against F. oxysporum. When fish effluents were sterilized by filtration or autoclaving, lower in vitro inhibition of P. ultimum and F. oxysporum was observed. Mixed fish effluents reduced tomato plant root colonization by P. ultimum (by up to 5.7-fold) and F. oxysporum (by up to 2.1-fold). These results showed that fish effluent can be used as soil amendments to promote plant growth and increase soil suppressiveness, which in turn can prevent soil-borne diseases.

Fish effluents promote root growth and suppress fungal diseases in tomato transplants

Gravel, V., Dorais, M., Dey, D. and Vandenberg, G. 2015. Fish effluents promote root growth and suppress fungal diseases in tomato transplants. Can. J. Plant Sci. 95: 427–436. Aquaculture systems generate large amounts of wastes which may constitute a beneficial amendment for horticultural crop in terms of nutrients, plant growth promoter and disease suppressiveness. This study aimed to determine (1) the nutrient value of rainbow trout farming effluents coming from two feed regimes and (2) the plant growth and disease suppressiveness effects of those fish farming effluents on tomato transplants. The effluent sludge from Skretting Orient™ (SO) had a higher content of P (38 vs. 32 mg L−1), K (23 vs. 11 mg L−1), N (19 vs. to 11 mg NO3 L−1; 186 vs. 123 mg NH4 L−1), and a higher NO3:NH4 ratio (1:9 vs. 1:13) compared with the Martin Classic (MC), while MC was richer in Mg (42 vs. 24 mg L−1) and Ca (217 vs. 169 mg L−1). For the first trial, a stimulating effect of the fish effluent was observed on plant height, leaf area and root dry biomass, while only the root biomass was increased during the second trial. Fish sludge was rich in microorganisms (97 and 142 µg fluorescein h−1 mL−1 for SO and MC, respectively) and their ability to suppress Pythium ultimum Trow and Fusarium oxysporum f.sp. lycopersici (Sacc.) Snyder & Hansen was observed. Both crude fish effluents reduced in vitro mycelial growth of P. ultimum and F. oxysporum, by 100 and 32%, respectively, while MC effluents showed a higher inhibition against F. oxysporum. When fish effluents were sterilized by filtration or autoclaving, lower in vitro inhibition of P. ultimum and F. oxysporum was observed. Mixed fish effluents reduced tomato plant root colonization by P. ultimum (by up to 5.7-fold) and F. oxysporum (by up to 2.1-fold). These results showed that fish effluent can be used as soil amendments to promote plant growth and increase soil suppressiveness, which in turn can prevent soil-borne diseases.

Maximizing Fish Effluent Utilization for Vegetable Seedling Production by Azospirillum Brasilense

Recycling of nutrients from organic sources and modifying farming practices towards sustainable agriculture have gained considerable attention in recent years. This is due to the growing awareness of the declining environmental quality and arable land, and significant depletion of oil and water reserves that drive agriculture production. This study evaluated the impacts of three Azospirillum brasilense strains (i.e. Sp7, Sp7-S and Sp245) on the growth of vegetable seedlings (i.e. tomato, lettuce and cucumber) fertilized with fish effluent. Seeds and seedlings were inoculated prior to germination and transplanting, respectively, and were grown in a greenhouse with natural light. Results show that inoculation with these strains increased root length and endogenous plant IAA (indole-3-acetic acid) of all vegetables. Inoculated tomato seedlings produced bigger leaves, higher dry plant biomass and protein content. Likewise, taller plants with bigger stems and more leaves, and higher fresh plant biomass were documented, but with Sp7 only. Strain Sp245 also triggered an increase of peroxidase enzyme activity. In lettuce, inoculation produced taller seedlings, more leaves and higher peroxidase activity. Chlorophyll and protein content were also increased, but with Sp7 only. In cucumber, inoculated seedlings increased seedling root biomass with higher total phosphorus content and peroxidase activity. Furthermore, inoculation caused little or no adverse impact on the fish effluent bacterial community indicating that these strains can be integrated into production system that utilizes fish effluent as a fertilizer, e.g. Aquaponics. A. brasilense could be a valuable agent to help maximize the usefulness of fish effluent or wastewater from freshwater aquaculture for plant production.

Effect of Flow Rate and Length of Gully on Lettuce Plants in Aquaponic and Hydroponic Systems

The main objective of this research is to study the effect of source of nutrients, water flow rate and length of gully to know the possibility of producing lettuce plants depending on the nutrients existing in effluent fish farm as compared with the lettuce production using standard nutrient solutions. To achieve that was studied the effect of source of nutrients (effluent fish water and nutrient solution), flow rate (1.0, 1.5 and 2.0 L min-1) and length of gully (2, 3 and 4 m) on the following parameters: nutrient uptake, dry weight and NO3-N content in plant. The obtained results indicated that the fresh and dry weight of shoots increased in nutrient solution over those of effluent fish farm. The fresh and dry weight of shoots decreased with increasing the flow rate and the length of gully. The dry weight of roots increased in nutrient solution over those of effluent fish farm. The dry weight of roots decreased with increasing the flow rate and the length of gully. The NO3-N content significantly increased in nutrient solution over those of effluent fish farm. The NO3-N content decreased with increasing the flow rate and length of gully. The NO3/protein ratio increased in nutrient solution over those of effluent fish farm.

Response of Potus Plants (Epipremnum Aureum) to Irrigation with Drainage Water of Ornamental Fish Basins and Magnesium Sulphate as Foliar Fertilizer

This study was carried out at the laboratory of National Research Centre, Egypt during two successive seasons on 2012 and 2013 to study the response of potus plants ( Epipremnum Aureum) irrigated by drainage water of ornamental fish basins diluted with tap water (DWOFB) at the concentrations 100% DWOFB, 75% DWOFB + 25% Tap water and 50% DWOFB + 50% Tap water) and interacted with magnesium sulphate as foliar fertilizer rate (MFFR) at the concentrations MFFR1 (25 ppm) and MFFR2 (50 ppm). The results indicated that, the plants watered with absolute fish effluent (100% fish) single or interacted with Mg 50 ppm performed the highest growth parameters, the highest percentage of carbohydrate and significant increase in photosynthetic pigments. The foliar application of Mg 50 ppm had positive effect on growth parameters and significantly increases in photosynthetic pigments. The plants irrigated with fish water effluent 75% followed by 50% had the second and the third largest average growth parameters and chemical constituents respectively.

Response of lettuce seedlings fertilized with fish effluent to Azospirillum brasilense inoculation

The continuous use of agrochemical inputs in modern agriculture for better crop productivity has resulted in unexpected environmental impact. This issue has raised public interest in exploring environmental friendly sustainable practices. In this study, three strains of Azospirillum brasilense (Sp7, Sp7-S and Sp245) were evaluated for their impacts on the growth of lettuce seedlings grown with fish effluent (FE) as a source of nutrients. Lettuce seeds were inoculated with these strains before sowing and at transplanting, and grown under greenhouse condition with natural light. Despite the existing indigenous microflora and low level of nutrients in the FE, the A. brasilense strains survived at populations ranging from 5 to 6 cfu g− 1 of roots and altered important agronomic traits, which led to growth enhancement. In particular, inoculated seedlings showed significant increase in the number of leaves, seedling height and root length. Chlorophyll and protein content were also improved, but only with Sp7 strain. However, the expression of pathogenesis-related protein, i.e., peroxidase, and level of endogenous indole-3-acetic acid increased by more than 50% in response to inoculation with the strains. Azospirillum inoculation also showed little or no adverse impact on the FE bacterial community indicating that it can be incorporated into a system that uses FE as a nutrient source, e.g., aquaponics. Thus, A. brasilense could be a valuable agent to help maximize the usefulness of FE or wastewater from freshwater aquaculture to further support plant growth.

Simultaneous C and N removal from saline salmon effluents in filter reactors comprising anoxic-anaerobic-aerobic processes: Effect of recycle ratio

Salmon processing generates saline effluents with high protein load. To treat these effluents, three compact tubular filter reactors were installed and an integrated anoxic/anaerobic/aerobic process was developed with recycling flow from the reactor's exit to the inlet stream in order to save organic matter (OM) for denitrification. The reactors were aerated in the upper section with recycle ratios (RR) of 0, 2, and 10, respectively, at 30°C. A tubular reactor behave as a plug flow reactor when RR = 0, and as a mixed flow reactor when recycle increases, thus, different RR values were used to evaluate how it affects the product distribution and the global performance. Diluted salmon process effluent was prepared as substrate. Using loads of 1.0 kg COD m−3d−1 and 0.15 kg total Kjeldahl nitrogen (TKN) m−3d−1 at HRT of 2 d, 100% removal efficiencies for nitrite and nitrate were achieved in the anoxic-denitrifying section without effect of the dissolved oxygen in the recycled flow on denitrification. Removals >98% for total organic carbon (TOC) was achieved in the three reactors. The RR had no effect on the TOC removal; nevertheless a higher efficiency in total nitrogen removal in the reactor with the highest recycle ratio was observed: 94.3% for RR = 10 and 46.6% for RR = 2. Results showed that the proposed layout with an alternative distribution in a compact reactor can efficiently treat high organic carbon and nitrogen concentrations from a saline fish effluent with OM savings in denitrification.

Development and Evaluation of PEG-Lithium Citrate Salt Based Aqueous Two Phase System and Its Application in Partitioning of Proteins from Fish Industry Effluent

A aqueous two phase system (ATPS) comprising of PEG (Average mol. Wt: 4000, 6000, 8000) – lithium citrate salt-water systems were studied. The basic studies like binodal curve data generation and equilibrium studies were carried out. Furthermore, the binodal model and Othmer-Tobias and Bancroft models for phase equilibria were used for reproducing the experimental binodal data and phase equilibrium composition data, respectively. Good agreement was obtained with the experimental binodal data and tie line data with the models. The effective excluded volume values were obtained from the binodal model for the present ATPS. The tie line length was determined through the phase equilibrium composition data. This system was used to partition crude proteins of the fish industry effluent. The effects of PEG and salt weight fraction in terms of tie line length and effective excluded volume on partitioning coefficient of crude protein were studied in detail. From the results it was observed that, the crude proteins present in the fish effluent were partitioned in the PEG rich phase and the maximum partition coefficient of 7.82 was obtained. The results are discussed in the context of practical potential of this citrate based ATPS in separating crude proteins from fish industry effluent.