Total Ammonia Nitrogen Removal Efficiency Research Articles

Rhizofiltration potential of floating aquatic macrophytes (FAMs) in Nile Tilapia (Oreochromis niloticus L.) tanks

Currently additional sustainable ways to mitigate the degradation of water quality are being researched all over the world. Phytoremediation is one of the serious efforts towards sustainability. The main objective of this study was to assess the rhizofiltration potential of water lettuce (Pistia stratiotes), common duckweed (Lemna minor) and mosquito fern (Azolla pinnata) on the removal of total ammonia-nitrogen (TAN) in circular outdoor tanks. Physico-chemical water quality parameters such as dissolved oxygen (DO), temperature and pH were also monitored. It was observed that the mean initial TAN concentration in all treatments were statistically comparable. In the final TAN concentration, tank with L. minor had the highest TAN concentration which was significantly different to tanks with P. stratiotes and A. pinnata. Likewise, tanks with L. minor had the lowest removal efficiency. For the DO concentration, it was observed that DO in all treatments was depleted in the first one week of the study. However, on the ninth day of the study, DO started to rise. Tanks with P. stratiotes had shown the highest trend among treatments. Mean temperature and pH in all treatments were statistically comparable. For the relationship of root length and TAN removal efficiency of floating aquatic macrophytes, it was observed that there was a strong positive correlation. These results show that the utilization of these floating aquatic macrophytes as bioremediator in small-scale tilapia production are feasible. In addition, other physico-chemical water quality parameters such as phosphorus, total dissolved solids, alkalinity, hardness, nitrate, and nitrite can be conducted.

Evaluation of the main pollutants present in Brazilian landfill leachates using ecotoxicity assays

The present study investigated the acute toxic effects caused by the main pollutants found in landfill leachates: total ammonia nitrogen (TAN), alkalinity, and humic substances (HS) for the test organisms Vibrio fischeri, Danio rerio, Daphnia similis, and Artemia sp. The leachates were obtained from two Brazilian landfills with different ages and operating modes. Air stripping and membrane filtration treatability experiments were performed to remove pollutants from the leachate. The results showed high toxicity of the raw leachate from both landfills for the studied organisms. In the individual treatments, air stripping achieved TAN and alkalinity removal efficiencies > 99%, and the membrane filtration treatment achieved HS removal efficiencies > 98%. Compared to the individual treatments, the combination of treatments resulted in the most significant reductions in leachate toxicity from both landfills for all test organisms studied. The principal component analysis showed a strong correlation between COD or HS parameters and the toxicity of V. fischeri and strong correlations between TAN and the toxicity of D. rerio, D. similis, and Artemia sp. Finally, this study highlights the application of a treatment route to remove acute toxicity from complex effluents, such as landfill leachate, to avoid potential environmental hazards to the aquatic ecosystem.

Mathematical modelling of an intermittent anoxic/aerobic MBBR: Estimation of nitrification rates and energy savings

This study aimed at modelling the performance of a novel MBBR configuration, named A/O-MBBR, comprised of a pre-anoxic reactor, with an HRT of 4.5 h, coupled with an intermittent anoxic/aerobic MBBR (HRT = 6.8 h). The lab-scale system was fed with municipal wastewater with an average influent Total Ammonia Nitrogen (TAN) and total COD (TCOD) concentrations of 46 mg of TAN-N L−1 and 310 mg TCOD L−1. During the whole experimental period, TAN removal efficiency was always higher than 96%; denitrification was also very effective, achieving nitrate and nitrite concentrations in the effluent both lower than 5 mg NOx-N L−1 on average. Moreover, TCOD average removal efficiency was equal to 85%. Modelling was performed to investigate the nitrification efficacy enhancement; to this aim, a biofilm model was developed, adopting the equations for mixed-culture biofilms and the Activated Model Sludge n°1 (ASM1) for the biological processes rates. The model allowed to determine the maximum uptake rate for autotrophic growth (μA was 2.5 d−1) and the semisaturation constant (KOA was 0.2 mg O2 L−1), suggesting that the nitrification process was 3-fold faster than average and very effective at low oxygen concentrations. The model estimated that about 85% of TAN was removed by the biofilm and only the remaining part by suspended biomass in the bulk liquid. Finally, it was assessed that the A/O-MBBR configuration allowed for a 45–60% savings of the energy requirement compared to a Benchmark WWTP layout.

Physical filtration of nutrients utilizing gravel-based and lightweight expanded clay aggregate (LECA) as growing media in aquaponic recirculation system (ARS)

The aquaponic recirculation system (ARS) combined aquaculture and hydroponic systems in a mutually beneficial environment. In this study, African catfish, Clarias gariepinus with Butterhead lettuce, Lactuca sativa were cultivated to evaluate gravel-based media and lightweight extended clay aggregate (LECA) as a physical filtration in the nutrient's removal. The performance of both tested growing media was assessed through the reduction of nutrient concentrations in the circulated water, which were total ammonia nitrogen (TAN), nitrite-nitrogen (NO2--N), nitrate-nitrogen (NO3--N), and phosphorus (PO43--P). Statistically, there were significant differences in the percentage of nutrient removal between gravel-based media and LECA treatment for TAN, NO2--N, NO3--N, and PO43--P. TAN removal efficiency achieved 92.47 ± 1.03% in LECA compared to 61.26 ± 2.69% in gravel-based media. For NO2--N, the removal efficiency was 77.25 ± 1.47% and 22.43 ± 6.84% in LECA and gravel-based media. The removal efficiency of NO3--N on LECA was two times more than gravel-based, 60.03 ± 1.58% and 30.77 ± 1.54%. The removal efficiency of PO43--P was 64.29 ± 1.82% for LECA while 27.43 ± 1.62% for gravel-based media. In addition, L. sativa yield was significantly higher in LECA with 64,961.71 ± 1295.61 g/m² as compared to 31,0582.82 ± 877.07 g/m² in gravel-based media. Significantly higher SGR of C. gariepinus in LECA with 3.94 ± 0.11%/day compared to 3.10 ± 0.12%/day in gravel-based media. LECA is an adsorptive substrate with a high removal capacity for phosphorus and nitrogen in aquaculture wastewater, increase its use as growing media in ARS or hydroponics.

Application of alginate-immobilized microalgae beads as biosorbent for removal of total ammonia and phosphorus from water of African cichlid (Labidochromis lividus) recirculating aquaculture system.

Immobilized microalgae are a promising approach to incorporate microalgae in recirculating aquaculture system (RAS) for water purification. In the present study, two types of biosorbents including sodium alginate-immobilized Scenedesmus spp. and Chlorella spp. beads (algal beads) and sodium alginate beads without microalgae (alginate beads) were prepared. In the first experiment (static test), the potential of two biosorbents to remove different concentrations of total ammonia nitrogen (TAN) and total phosphorus (TP) from water was investigated. In the second experiment, two prepared biosorbents were used as biofilter in a RAS for rearing African cichlid (Labidochromis lividus) for 30 days. The survival rate and growth indices of fingerling fish and removal efficiency of two biosorbents for TAN, NO3-N, and TP were determined. The results of static test showed that the removal efficiency and uptake capacity of the two biosorbents for TAN and TP increased during 30 days of the experiment, and these values for the algal beads were higher than the alginate beads. The TAN removal efficiency of the two biosorbents increased with increasing TAN concentration from 0.5 to 5 mg L-1. The application of algal beads in the RAS improved the survival rate, final weight, final length, weight gain, and daily growth index (DGI%) indices of fish compared to those cultured in the RAS containing the alginate beads and the control (P<0.05). The algal and alginate beads decreased the TAN concentration by 42.85% and 28.57% compared to the control after 30 days of cultivation period, respectively. The uptake of nitrate was not observed by the two biosorbents during cultivation period. The TP removal efficiency of algal beads reached 44.90% after 30 days. The findings of this study indicated that the sodium alginate-immobilized microalgae could be considered as a suitable biofilter to be incorporated into a RAS to improve water quality and consequently enhance the growth and health of fish.

Ammonia nitrogen removal from coking wastewater and high quality gypsum recovery by struvite recycling by using calcium hydroxide as decomposer

This study deals with the highly significant and cost-effective pretreatment of the high concentration of the Total Ammonia Nitrogen (TAN) in coking wastewater to improve the biodegradability. Struvite crystallization is a promising process for TAN removal, but the high operating cost hinders its application. To solve this problem, a novel struvite recycling process was proposed for pre-treating TAN present in the coking wastewater, within which struvite was decomposed in the solid-liquid system using Ca(OH)2 as the decomposer. The results indicates that 91% of ammonium in struvite could be stripped out from the decomposition solution, with Ca(OH)2:NH4+ in the molar ratio of 2:1, temperature at 35 °C and a gas to liquid volume ratio of 3500. The resulting solution, post the escape of the ammonia, was dissolved by sulfuric acid. Approximately 100% of the phosphate and magnesium were observed to be released from the insoluble phosphate compounds, resulting in the formation of high-purity gypsum. A TAN removal efficiency of 89% could be achieved by reusing the supernatant after the dissolution of the decomposition product, at pH 9.5 and the Mg:TAN:PO4–P molar ratio of 1.2:1:1. The pilot-scale test demonstrated that approximately 86% TAN was removed from the coking wastewater and the purity of recovered could reach over 99%. Further economic analysis proves that the operation cost of the proposed process is 0.55$ per m3 of coking wastewater, showing a 73% cost reduction when compared to struvite crystallization without recycling.

Effect of mixing ratios of natural inorganic additives in removing ammonia and sulfide in the liquid phase during anaerobic digestion of slaughterhouse waste

In this study, the efficacy of inorganic additives in the removal of total ammonia nitrogen (TAN) and sulfide in the aqueous phase of slaughterhouse waste undergoing anaerobic digestion in the batch reactor was investigated. A mixture of natural inorganic additives processed from the anthill and red rock soil samples collected from Arusha, Tanzania were used as adsorbents in different ratios. These materials were chosen in regard to their abundance in the local environment, surface properties, and elemental composition. Before analysis, the materials were pulverized and calcined at 700 and 900 °C for 2 h in a furnace and then sieved to 250 μm fine particle size. XRD analysis revealed that the anthill soil sample is endowed with major mineral phases of quartz and hematite while red rock soil contains albite, pyroxene, and quartz as predominant phases. The anthill and red rock soil samples calcined at 900 °C displayed higher BET surface areas of 815.35 and 852.35 m2/g, respectively. The mixture of anthill soil and red rock soil in a ratio of 3:1 had a higher TAN removal efficiency of 92% at a contact time of 30 min compared to other ratios. On the other hand, a ratio of 1:2 showed a higher sulfide removal efficiency of 79% at a contact time of 60 min. Adsorption isotherm studies revealed that the Jovanovich model fitted better to the experimental data than the Langmuir and Freundlich models. The results demonstrated further that inorganic additives have a synergistic effect on stimulating methanogenesis as well as eliminating ammonia and sulfide during anaerobic digestion of slaughterhouse waste. Our findings demonstrate that anthill and red rock soils can be exploited as affordable, ecofriendly, and efficient adsorbents for mitigation of TAN and sulfide from the liquid phase and sustenance of methanogenesis.

Effect of pore size of monofilament woven filter cloth as supporting material for dynamic membrane filtration on performance using aerobic membrane bioreactor technology

AbstractDynamic membranes (DMs) defined as cake layer forms on a support material such as filter cloth have been of great interest in recent years. The usage of DMs can reduce the capital cost significantly and energy consumption during wastewater treatment by replacing the conventional membrane. The formation of an active dynamic cake layer is highly related to the retention of particles on the support material surface. In this study, different pore sizes of monofilament woven filter cloth made of polypropylene (PP; 20, 40, and 60 μm) were installed as a flat sheet in a DM bioreactor (DMBR) to treat high strength food wastewater [&gt;1,000 mg/L chemical oxygen demand (COD)]. The wastewater treatment performances, namely COD, turbidity, total solid separation, and total ammonia nitrogen removal efficiencies, were assessed daily. The system achieved average COD removals higher than 80% and 70% for smaller pore size and larger pore size, respectively. Based on the results (duration of 4 days), the 20 μm pore size monofilament filter cloth was found most suitable for the cake layer development. The results also demonstrate that the biofilm composed of the cake layer of the DM on smaller pore size significantly concurs with the high treatment efficiency compared with the larger pore size.

Nitrification in the presence of sulfide and organic matter in a sequencing moving bed biofilm reactor (SMBBR) with zeolite as biomass carrier

AbstractBACKGROUNDThe biological nitrification process is inhibited in the presence of sulfide and organic matter (OM). The use of immobilized biomass on inert carriers may help to decrease this inhibition. Thus, the main goal of the present work was to develop a sequencing moving bed biofilm reactor (SMBBR) using zeolite as biomass carrier and to determine its performance in presence of sulfide and OM.RESULTSThe use of zeolite as biomass carrier improves both the total ammonia nitrogen (TAN) oxidation and nitrate accumulation, allowing the system to be able to treat higher nitrogen loading rates. The SMBBR with zeolite in presence of sulfide and OM performed nitrification better than a sequencing batch reactor (SBR), by keeping the TAN and chemical oxygen demand (COD) removal efficiency at &gt;90% for both inhibitory conditions. The SMBBR also is able to degrade COD by ≤98%. Finally, biomass with zeolite settled faster than biomass without zeolite, improving the sludge volume index (SVI) by 53.8%.CONCLUSIONSIt was possible to develop a SMBBR system using zeolite as biomass carrier. The SMBBR could maintain a nitrifying system under inhibitory conditions, allowing efficiencies of TAN and COD removal as high as 90%. © 2019 Society of Chemical Industry

Simple improvement of digested sludge quality: is postaeration the key?

Postaeration, where digested sludge is introduced into aerobic conditions, is a technology that could improve the quality of sludge and sludge liquor in many ways. Although it is a fairly simple process, only few data about the effect of postaeration have been published. In this study, batch experiments have been performed first, indicating that postaeration affects the total ammonia nitrogen (TAN) and sludge dewaterability. In the removal of TAN, both stripping and biological oxidation can play an important role depending on specific condition. Then the postaeration was investigated in a semicontinuous batch reactor. In addition, the effect of postaeration on the concentration of selected micropollutants such as pharmaceuticals, EOX and AOX was studied. The hydraulic retention time (HRT) of 8, 6, 4 and 2 days and different aeration intensities were tested. The TAN removal efficiency achieved was about 40-60%, sludge dewaterability expressed by sludge cake total solids (TS) concentration after dewatering improved relatively by 5-30%. In addition, TS degradation is also taking place and therefore the reduction of the amount of final sludge to be disposed could be even higher. The biggest changes in observed parameters were recorded at the longest HRT.

Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Application of biofloc technology could effectively treat wastewater. However, the effect of influent carbon to nitrogen ratio (C/N ratio) on water quality and microbial community structure evolution in suspended growth bioreactors (SGBRs) through biofloc technology is still unclear. Here, we show that the total ammonia nitrogen (TAN) and nitrite nitrogen in the effluent of the C/N 10 treatment was significantly higher than that in the C/N 15, C/N 20 and C/N 25 treatments (p &lt; 0.05). Higher TAN removal efficiency was obtained in treatments of C/N 15, C/N 20 and C/N 25, and there was no accumulation of nitrite nitrogen and nitrate nitrogen. Increasing the C/N ratio strengthened the elimination ability of total phosphorus and chemical oxygen demand (COD). The concentrations of TAN and COD first dropped to the lowest level and then increased slightly within one cycle in all treatments. The accumulation of biomass in the reactors increased with the increasing C/N ratio, indicating that a higher C/N ratio was conducive to microbial proliferation. The 16S rRNA sequencing revealed that the microbial community diversity in SGBRs was significantly higher than that in the natural wastewater (P0). The predominant phylum were Proteobacteria, Bacteroidetes and Verrucomicrobia, but Saccharibacteria occupied a dominant position in the late period of the experiment. Pathogens, such as Aeromonas, Acidovorax, Flavobacterium, and Malikia were significantly decreased after high C/N ratio simulative wastewater treating natural wastewater in the reactors. In summary, the water quality and biomass concentrations in SGBRs can be improved under the conditions of influent C/N ratio, equal to or greater than 15.

The concept of load ratio applied to bioelectrochemical systems for ammonia recovery

AbstractBACKGROUNDThe load ratio is a crucial parameter to optimize the current driven recovery of total ammonia nitrogen (TAN) from urine. The load ratio is the ratio between the current density and the TAN loading rate. It is currently not known if the load ratio concept applies to a bioelectrochemical system (BES) because the current density and TAN loading rate cannot be controlled independently.RESULTSWe found a clear increasing trend in TAN removal efficiency with respect to load ratio in the BES for both human and synthetic urine. The maximum TAN removal efficiency was 60.9% at a load ratio of 0.7, corresponding to a TAN transport rate of 119 gN m−2 day−1 at an electrical energy input of 1.9 kWh kgN−1 (synthetic urine). Low load ratios (&lt;1) were obtained, indicating that the current was not enough to transport all the TAN across the membrane.CONCLUSIONSBES and ES show the same general relationship between TAN removal efficiency and load ratio. Therefore, given a stable current density, the concept of load ratio can also predict the TAN removal efficiency in BES. Higher current densities, and insights into the factors limiting current, are needed to increase the load ratio and therefore the TAN removal efficiency. © 2019 The Authors. Journal of Chemical Technology &amp; Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry.

Hydrogen Gas Recycling for Energy Efficient Ammonia Recovery in Electrochemical Systems.

Recycling of hydrogen gas (H2) produced at the cathode to the anode in an electrochemical system allows for energy efficient TAN (Total Ammonia Nitrogen) recovery. Using a H2 recycling electrochemical system (HRES) we achieved high TAN transport rates at low energy input. At a current density of 20 A m-2, TAN removal rate from the influent was 151 gN m-2 d-1 at an energy demand of 26.1 kJ gN-1. The maximum TAN transport rate of 335 gN m-2 d-1 was achieved at a current density of 50 A m-2 and an energy demand of 56.3 kJ gN-1. High TAN removal efficiency (73-82%) and recovery (60-73%) were reached in all experiments. Therefore, our HRES is a promising alternative for electrochemical and bioelectrochemical TAN recovery. Advantages are the lower energy input and lower risk of chloride oxidation compared to electrochemical technologies and high rates and independence of organic matter compared to bioelectrochemical systems.

Electrochemical Treatment of Recirculating Aquaculture Wastewater Using a Ti/RuO2-IrO2 Anode for Synergetic Total Ammonia Nitrogen and Nitrite Removal and Disinfection

Wastewater treatment and biosecurity are essential for intensive recirculating aquaculture system (RAS) production. In this study, the viability of the electrochemical process using a Ti/RuO2-IrO2 anode for synergetic total ammonia nitrogen (TAN) and nitrite removal and disinfection of semi-commercial RAS wastewater was evaluated. During the electrochemical oxidation process, the effects of the applied current density, sodium chloride concentration, and initial pH on the removal of TAN and nitrite were investigated. Experiment results indicated that under the conditions of 1.7 g L-1 sodium chloride concentration and 60 min electrolysis time, TAN removal efficiencies reached 78% at a current density of 60 mA cm-2, while nitrite removal efficiencies reached more than 95% at a current density of 30 mA cm-2. TAN removal due to an indirect oxidation mechanism followed second-order kinetics, while nitrite removal was described by pseudo-first-order kinetics in low-salt water (1.7 g L-1). The kinetics for electro-oxidation of TAN and nitrite affected by the current density were expressed as kTAN = 1.0 x 10-5 J-0.0002 and kNO2- = 1.9 x 10-3 J-0.0041, respectively. For disinfection, the active chlorine in situ generated by electrochemical treatment caused and inactivation. The results showed that the two objective pathogens can be sterilized rapidly, which indicated that no extra treatment for disinfection was needed. Finally, a comparison was made of the energy consumption in this study with those in the literature. This study showed that the Ti/RuO2-IrO2 anodic oxidation process has a potential for sustainable RAS wastewater treatment.

Repeatedly using the decomposition product of struvite by ultrasound stripping to remove ammonia nitrogen from landfill leachate

In this study, the decomposition of struvite by ultrasound stripping and the recycle use of the decomposition product for the treatment of landfill leachate were investigated. The results indicated that when the decomposition of struvite by ultrasound stripping was performed at 55°C for 40min, the ammonium in the struvite could be almost completely eliminated from the solution system. The characterization analysis showed that magnesium phosphate and the dissolved phosphate ions were the main active derivatives. Approximately 90% of the total ammonia nitrogen (TAN) in landfill leachate can be removed by reusing the decomposition product at pH 9 for 60min. Repeated use of the struvite decomposition product revealed that the TAN removal efficiency decreased with an increase in the number of recycles. However, in the process of multiple recycling, about 90% of TAN removal could be maintained by supplementing a certain amount of the preformed struvite to the solution for every recycle. An economic analysis demonstrated that 79.3% of the treatment cost could be saved by the proposed process compared to the non-recycling process.

Nutrients removal from swine wastewater by struvite precipitation recycling technology with the use of Mg3(PO4)2 as active component

The recovery and removal of nutrients from swine wastewater was investigated by employing a struvite recycling process, which used magnesium phosphate (MP) as the active component. In this study, the effect of organic matters (sodium alginate, bovine albumin and acetic acid) in swine wastewater on the crystallization of struvite and the feasibility of MP as the phosphate and magnesium sources of struvite precipitation were first evaluated. The results demonstrated that sodium alginate and bovine albumin could slightly influence the crystallization of struvite while acetic acid did not. Using MP as the phosphate and magnesium sources of struvite precipitation could achieve a removal efficiency of the total ammonia nitrogen (TAN) close to that of using pure chemicals (MgCl2∙6H2O and Na2HPO4∙12H2O). The results of struvite pyrgenation revealed that the optimal pyrogenation condition of struvite was at Mg(OH)2:NH4+ 1:1 and temperature 150°C for 3h, at which the main pyrogenation product was MP. Recycling the pyrolysate at pH 8.5 could achieve a TAN removal of 78%. When the pyrolysate was recycled for six cycles, the TAN removal efficiency could be maintained above 70%, and 67% of the struvite precipitation cost could be reduced compared to using pure chemicals.

Recycling struvite pyrolysate obtained at negative pressure for ammonia nitrogen removal from landfill leachate

Struvite precipitation coupling low-cost materials and recycling was used to remove the total ammonia nitrogen (TAN) from landfill leachate in order to reduce the overall cost of precipitator. Struvite used for recycling was formed using a stabilizing agent (SA) as the precursor, which was formulated by using phosphorus acid and low-grade magnesium oxide (LG-MgO). Results showed that use of SA and LG-MgO for struvite precipitation can achieve TAN removal near that obtained by using pure chemicals. The results of struvite decomposition indicated that maintaining a negative pressure in struvite pyrogenation has a significant effect on the improvement of the ammonium release rate. When struvite pyrogenation was conducted at a vacuum degree of 0.04MPa and at a temperature of 120°C for 3h, the ammonium release rate was >90%. The obtained pyrolysate was recycled for the treatment of landfill leachate without the addition of other chemicals, and the TAN removal efficiency was comparable to that by struvite precipitation using fresh chemicals. When pyrolysate was used repeatedly by supplementing LG-MgO at the MgO:MgHPO4 molar ratio of 0.5:1 and by prolonging the stirring time to 2h, a TAN removal efficiency >68% could be maintained in the eight-cycle process. Economic analysis revealed that the proposed recycling process could reduce 86% of the cost of struvite precipitation using pure chemicals.

Nutrient removal efficiency ofHydropuntia corneain an integrated closed recirculation system with pink shrimpFarfantepenaeus brasiliensis

In this study, we have tested the effect of seaweed stocking density in an experimental seaweed biofilter using the economically important red seaweed Hydropuntia cornea integrated with the cultivation of the pink shrimp Farfantepenaeus brasiliensis. Nutrient removal efficiency was evaluated in relation to seaweed stocking density (2.5, 4, 6 and 8 g fw L−1). Total ammonia nitrogen (TAN) was the main nitrogen source excreted by F. brasiliensis, with concentrations ranging from 41.6 to 65 μM of NH4+-N. H. cornea specific growth rates ranged from 0.8 ± 0.2 to 1.4 ± 0.5% day−1 with lowest growth rates at higher seaweed stocking density (8 g fw L−1). Nutrient removal was positively correlated with the cultivation densities in the system. TAN removal efficiency increased from 61 to 88.5% with increasing seaweed stocking density. Changes in the chemical composition of the seaweed were analysed and correlated with nutrient enrichment from shrimp effluent. The red seaweed H. cornea can be cultured and used to remove nutrients from shrimp effluents in an integrated multi-trophic aquaculture system applied to a closed recirculation system. Recirculation through seaweed biofilters in land-based intensive aquaculture farms can also be a tool to increase recirculation practices and establish full recirculation aquaculture systems (RAS) with all their known associated benefits.

Optimization of factors with C/N ratio and flocs biomass concentration in simulated aquaculture bio-flocs systems by response surface methodology

The TAN (total ammonia nitrogen) removal efficiency was investigated in simulated aquaculture bio-flocs technology systems. The response surface methodology that was applied with a central composite rotational design and two key operational parameters, flocs biomass concentration and C/N ratio was varied in order to evaluate the system performance and achieve the optimal operational conditions in this study. A polynomial linear regression model was found to quantitatively describe the relationship between the two variables and response values with adequate fitness in the simulate aquaculture bio-flocs systems. The results showed that flocs biomass concentration and operational C/N ratio both had significant impacts on the response objectives, as well as the interactions between them. The optimal results attained from the model indicated that more than 90% TAN removal efficiency was achieved when the flocs biomass concentration and C/N ratio were around 2.0–2.5 (volatile suspended solids, g/l) and 13–16, respectively.

Evaluation of three types of structured floating plastic media in moving bed biofilters for total ammonia nitrogen removal in a low salinity hatchery recirculating aquaculture system

Three different commercially available structural plastic media were evaluated in triplicate in moving bed biofilters under low salinity (11–12 ppt) warm water culture conditions and two different feed loading rates. The culture system consisted of nine separate modules that include a double drain fish culture tank paired to a moving bed biofilter. The biofilters were filled with 0.11 m 3 of one of three different types of floating plastic structured media. The three types of media evaluated were K1 kaldnes media, MB3 media, and AMB media. Volumetric total ammonia nitrogen (TAN) removal rates (g TAN removed/m 3 media-day), TAN removal efficiency, and biofilm kinetic constants, K i (h −1) were determined for the three media types at two different daily feed load rates of 3.5 and 8.2 kg feed/m 3 media. The feed provided was a 4.8 mm slow sinking marine grower diet pellet (45% protein, 17% fat). Average (±standard deviation, SD) volumetric TAN removal rates (VTR) at the lower feed load for the three media types were 92.2 ± 26.3, 86.1 ± 27.5, and 82.5 ± 25.9 for the MB3, AMB, and K1 kaldnes media, respectively. At the higher feed load the average VTR for the three media types was 186.4 ± 53.7, 172.9 ± 47.8, and 139.9 ± 38.9 for the MB3, AMB, and K1 kaldnes media, respectively. Influent TAN concentrations varied by the feed load rate and ranged from 0.55 to 0.93 mg/L and 0.83 to 1.87 mg/L for the low and higher feed loads, respectively. The percent TAN removal rates for the MB3 media was the highest of the three media types at both the low and high feed load rates averaging 12.3% and 14.4%, respectively. The MB3 media was selected for use in the moving bed biofilters because of the greater VTR and removal efficiency results for use in the 0.11 m 3 moving bed biofilters of the hatchery recirculating aquaculture system.