TiO2-PES Fibrous Composite Material for Ammonia Removal Using UV-A Photocatalyst

This study focused on the development and characterization of TiO2-PES composite fibers with varying TiO2 loading amounts using a phase inversion process. The resulting composite fibers exhibited a sponge-like structure with embedded TiO2 nanoparticles within a polymer matrix. Their photocatalytic performance for ammonia removal from aqueous solutions under UV-A light exposure was thoroughly investigated. The findings revealed that PeTi8 composite fibers displayed superior adsorption capacity compared to other samples. Moreover, the study explored the impact of pH, light intensity, and catalyst dosage on the photocatalytic degradation of ammonia. Adsorption equilibrium isotherms closely followed the Langmuir model, with the results indicating a correlation between qm values of 2.49 mg/g and the porous structure of the adsorbents. The research underscored the efficacy of TiO2 composite fibers in the photocatalytic removal of aqueous under UV-A light. Notably, increasing the distance between the photocatalyst and the light source resulted in de-creased hydroxyl radical concentration, influencing photocatalytic efficiency. These findings contribute to our understanding of TiO2 composite fibers as promising photocatalysts for ammonia removal in water treatment applications.

An assessment Protocal of Ammonia Removal Efficacy for Air Purification Products

A device is designed to assess the ammonia removal effect of passive air purification products which derived the QB/T 2761-2006 Methods for determination of purificatory effect of indoor environment decontamination product.The device is composed of three parts:ammonia generator,ammonia removal device and ammonia collection device,which is made up of common laboratory equipment.The reagents used are common acid and alkali reagents in the laboratory.During the experiment,5.0mL of 25%concentrated ammonia water is added to the ammonia generator as the ammonia source,and filter paper is used as the sample carrier.Take 3.0g sample and add it to the filter paper,after the ammonia is absorbed by the filter paper with the sample,the residual ammonia is collected and measured by acid-base titration.The ammonia removal efficacy of the sample is calculated by the ammonia absorption amount of the blank sample and the sample to be tested.This method has the characteristics of simple equipment,small area,toxic or harmful substance free,and fabulous accuracy.Four different samples were tested,and the results matched the standard method.

Ammonia removal from low-strength municipal wastewater by powdered resin combined with simultaneous recovery as struvite

Low-strength municipal wastewater is considered to be a recoverable nutrient resource with economic and environmental benefits.Thus,various technologies for nutrient removal and recovery have been developed.In this paper,powdered ion exchange resin was employed for ammonia removal and recovery from imitated low-strength municipal wastewater.The effects of various working conditions(powdered resin dosage,initial concentration,and pH value)were studied in batch experiments to investigate the feasibility of the approach and to achieve performance optimization.The maximum adsorption capacity determined by the Langmuir model was 44.39 mg/g,which is comparable to traditional ion exchange resin.Further,the effects of co-existing cations(Ca^(2+),Mg^(2+),K^(+))were studied.Based on the above experiments,recovery of ammonia as struvite was successfully achieved by a proposed two-stage crystallization process coupled with a powdered resin ion exchange process.Scanning electron microscopy(SEM)and X-ray diffractometry(XRD)results revealed that struvite crystals were successfully gained in alkaline conditions(pH=10).This research demonstrates that a powdered resin and two-stage crystallization process provide an innovative and promising means for highly efficient and easy recovery from low-strength municipal wastewater.

Preparation of Clay/Biochar Composite Adsorption Particle and Performance for Ammonia Nitrogen Removal from Aqueous Solution

This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance of NH4^+-N by composite adsorption particle was monitored under different raw material proportions and initial NH4^+-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH4^+-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH4^+-N concentration of 20 mg L^-1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH4^+-N removal from surface water.

Removal of high concentrated ammonia nitrogen from landfill leachate by landfilled waste layer

The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste collected in Shanghai, China, which was characterized by high food waste content. The NH + 4 removal efficiency in the system of SBR nitrifying reactor followed by fresh and matured landfilled waste layer in series was studied. In the nitrifying reactor, above 90% of NH + 4 in leachate was oxidized to NO - 2 and NO - 3. Then high concentrated NO - 2 and NO - 3 were removed in the way of denitrification process in fresh landfilled waste layer. At the same time, degradation of fresh landfilled waste was accelerated. Up to the day 120, 136.5 gC/(kg dry waste) and 17.9 gN/(kg dry waste) were converted from waste layer. It accounted for 50.15% and 86.89% of the total carbon and nitrogen content of preliminary fresh waste, which was 4.42 times and 5.17 times higher than that of reference column respectively. After filtering through matured landfilled waste, BOD 5 concentration in leachate dropped to below 100 mg/L, which would not affect following nitrification adversely. Because the matured landfilled waste acted as a well methanogenic reactor, 23% of carbon produced accumulatively from fresh landfilled waste degradation was converted into CH 4.

Enhanced biological nutrient removal by the alliance of a heterotrophic nitrifying strain with a nitrogen removing ecosystem

Nitrogen removal from synthetic wastewater was investigated in an airlift bioreactor （ALB）, augmented with a novel heterotrophic nitrifier Pseudonocardia ammonioxydans H9^T under organic carbon to nitrogen ratios （Corg/N） ranging from 0 to 12. Effect of the inoculated strain was also determined on the settling properties and the removal of chemical oxygen demand （COD）. Two laboratory scale reactors were set up to achieve a stable nitrifying state under the same physicochemical conditions of hydraulic retention time （HRT）, temperature, pH and dissolved oxygen （DO）, and operated under the sequencing batch mode. The level of DO was kept at 0.5- 1.5 mg/L by periodic stirring and aeration. Each specific Corg/N ratio was continued for duration of 3 weeks. One of the reactors （BR2） was inoculated with P ammonioxydans H9^T periodically at the start of each Corg/N ratio. Sludge volumetric index （SVI） improved with the increasing Corg/N ratio, but no significant difference was detected between the two reactors. BR2 showed higher levels of nitrogen removal with the increasing heterotrophic conditions, and the ammonia removal reached to the level of 82%-88%, up to10% higher than that in the control reactor （BR1） at Corg/N ratios higher than 6; however, the ammonia removal level in experimental reactor was up to 8% lower than that in control reactor at Corg/N ratios lower than 2. The COD removal efficiency progressively increased with the increasing Corg/N ratios in both of the reactors. The COD removal percentage up to peak values of 88%-94% in BR2, up to 11% higher than that in BR1 at Corg/N ratio higher than 4. The peak values of ammonia and COD removal almost coincided with the highest number （18%-27% to total bacterial number） of the exogenous bacterium in the BR2, detected as colony forming units （CFU）. Furthermore, the removal of ammonia and COD in BR2 was closely related to the number of the inoculated strain with a coefficient index （R2） up to 0.82 and 0.85 for ammonia and COD, respectively. These results suggest that it was more efficient for both the ammonia and carbon nutrient removals in a reactor inoculated with a heterotrophic nitrifier at high Corg/N ratio, inferring that the heterotrophic nitrifers would be practically more available in the treatment of wastewater with high level of ammonia and COD.

Regenerable adsorbent for removing ammonia evolved from anaerobic reaction of animal urine

The waste gas evolved from biodegradation of animal urine contains ammonia causing environmental concerns. A new and effective method for removing ammonia from such waste gas using reactive adsorption is presented. In the process, activated carbon impregnated with H2SO4（H2SO4/C） is employed. Ammonia in the waste gas reacts with H2SO4 on the adsorbent instantaneously and completely to form （NIL）2SO4. The H2SO4/C adsorbent is high in NH3 adsorption capacity and regenerable. The NH3 removal capacity of this regenerable adsorbent is more than 30 times that of the adsorbents used normally in the industry. The spent H2SO4/C is regenerated by flowing low-pressure steam through the adsorbent bed to remove the （NH4）2SO4 from the adsorbent. The regeneration by-product is concentrated （NH4）2SO4 solution, which is a perfect liquid fertilizer for local use. Re-soaking the activated carbon with H2SO4 solution rejuvenates the activity of the adsorbent. Thus the H2SOJC can be reused repeatedly. In the mechanism of this reactive adsorption process, trace of H20 in the waste gas is a required, which lends itself to treating ammonia gas saturated with moisture from biodegradation of animal urine.

Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products（DBPs） may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine（NDMA）, may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes.The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon（PAC） sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than67% ammonia and 70%–100% N-nitrosamine precursors were removed by Mordenite zeolite（except 3-（dimethylaminomethyl）indole（DMAI） and 4-dimethylaminoantipyrine（DMAP））. PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors（dimethylamine（DMA）, ethylmethylamine（EMA）, diethylamine（DEA）, dipropylamine（DPA）, trimethylamine（TMA）, DMAP, and DMAI） during the alum coagulation process.

A bioaugmentation failure caused by phage infection and weak biofilm formation ability

Two biological aerated filters （BAF） were setup for ammonia removal treatment of the circulation water in a marine aquaculture. One of the BAFs was bioaugmented with a heterotrophic nitrifying bacterium, Lutimonas sp. H10, where the ammonia removal was not improved and the massive inoculation was even followed by a nitrification breakdown from day 9 to 18. The nitrification was remained stable in control BAF operated under the same conditions. Fluorescent in situ hybridization （FISH） with rRNA-targeted probes and cultivable method revealed that Lutimonas sp. H10 almost disappeared from the bioaugomented BAF within 3 d, and this was mainly due to the infection of a specific phage as revealed by flask experiment, plaque assay and transmission electron observation. Analyses of 16S rRNA gene libraries showed that bacterial groups from two reactors evolved differently and an overgrowth of protozoa was observed in the bioaugmented BAF. Therefore, phage infection and poor biofilm forming ability of the inoculated strain are the main reasons for bioaugmentation failure. In addition, grazing by protozoa of the bacteria might be the reason for the nitrification breakdown in bioaugmented BAF during day 9-18.

Ammonia and phosphorus removal from using cash crop waste-derived agricultural runoff biochars

Adsorption of biochars(BC)produced from cash crop residuals is an economical and practical technology for removing nutrients from agricultural runoff.In this study,B C made of orange tree trunks and tea tree twigs from the Laoguanhe Basin were produced and modified by aluminum chloride(Al-modified)and ferric sulfate solutions(Fe-modified)under various pyrolysis temperatures(200℃-600℃)and residence times(2-5 h).All produced and modified B C were further analyzed for their abilities to adsorb ammonia and phosphorus with initial concentrations of 10-40 mg/L and 4-12 mg/L,respectively.Fe-modified Tea Tree B C 2h/400℃showed the highest phosphorus adsorption capacity of 0.56 mg/g.Al-modified Orange Tree B C 3h/500℃showed the best performance for ammonia removal with an adsorption capacity of 1.72 mg/g.FTIR characterization showed that P=O bonds were formed after the adsoiption of phosphorus by modified BC,N-H bonds were formed after ammonia adsorption.X P S analysis revealed that the key process of ammonia adsorption was the ion exchange between K+and N H 44.Phosphorus adsorption was related to oxidation and interaction between PO43-and Fe3+.According to X R D results,ammonia was found in the form of potassium amide,while phosphorus was found in the form of iron hydrogen phosphates.The sorption isotherms showed that the Freundlich equation fits better for phosphorus adsorption,while the Langmuir equation fits better for ammonia adsorption.The simulated runoff infiltration experiment showed that 97.3%of ammonia was removed by Al-modified Orange tree B C 3h/500℃,and 92.9%of phosphorus was removed by Fe-modified Tea tree B C 2h/400℃.

Study on the mechanism of copper-ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal

Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method（SFM） was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.

Simultaneous nitrification and denitrification conducted by Halomonas venusta MA-ZP17-13 under low temperature conditions

Nitrification is a key step in the global nitrogen cycle.Compared with autotrophic nitrification,heterotrophic nitrification remains poorly understood.In this study,Halomonas venusta MA-ZP17-13,isolated from seawater in shrimp aquaculture (Penaeus vannamei),could simultaneously undertake nitrification and denitrification.With the initial ammonium concentration at 100 mg/L,the maximum ammonium-nitrogen removal rate reached98.7%under the optimal conditions including C/N concentration ratio at 5.95,p H at 8.93,and Na Cl at 2.33%.The corresponding average removal rate was 1.37 mg/(L·h)(according to nitrogen) in 3 d at 11.2℃.By whole genome sequencing and analysis,nitrification-and denitrification-related genes were identified,including ammonia monooxygenase,nitrate reductase,nitrite reductase,nitric oxide dioxygenase and nitric oxide synthase;while no gene encoding hydroxylamine oxidase was identified,it implied the existence of a novel nitrification pathway from hydroxylamine to nitrate.These results indicate heterotrophic bacterium H.venusta MA-ZP17-13 can undertake simultaneous nitrification and denitrification at low temperature and has potential for NH_(4)^(+)-N/NH_(3)-N removal in marine aquaculture systems.

Effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product

The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25—28℃, pH 7.5? ?.0 , and the influent ammonia nitrogen of 40—70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl - 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much high chlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrification to nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the total domestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organics declined obviously(less than 60%). It was found that the effect of seawater salinity on the removal of organics was negative rather than positive one as shown for ammonia removal.

Electrochemical removal of ammonium nitrogen in high efficiency and N_(2) selectivity using non-noble single-atomic iron catalyst

Ammonia nitrogen (NH_(4)^(+)-N) is a ubiquitous environmental pollutant,especially in offshore aquaculture systems.Electrochemical oxidation is very promising to remove NH_(4)^(+)-N,but suffers from the use of precious metals anodes.In this work,a robust and cheap electrocatalyst,iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C),was developed for electrochemical removal of NH_(4)^(+)-N from in wastewater containing chloride.The FeSAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon(Fe-NPs/N-C),unmodified carbon and conventional Ti/IrO_(2)-TiO_(2)-RuO_(2)electrodes.And high removal efficiency (>99%) could be achieved as well as high N_(2)selectivity (99.5%) at low current density.Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH_(4)^(+)-N.This study provides promising inexpensive catalysts for NH_(4)^(+)-N removal in aquaculture wastewater.

Removing ammonia from air with a constant pH, slightly acidic water spray wet scrubber using recycled scrubbing solution

Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this studywas to determine if a spray scrubber with slightly acidic and higher p H scrubbing solution （pH from 2 to 8） could effectively remove NH3 from NH3 laden air （such as animal building exhaust air）, and also collect this valuable resource for rater use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH3/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8while maintaining constant air velocity at 1.3 m. s-1. Next, air velocity was increased （2and 3 m.s-1） while solution pH remained constant at pH6. At 1.3 m.s -1, NH3 removal efficiencies ranged between 49.0% （pH8） and 84.3% （pH2）. This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH3 molecules. The NH3 removed from the air was held in solution as NH4＋ and accumulates over time so the solution should be an excellent fertilizer.

Recent advances in application of moving bed bioreactors for wastewater treatment from recirculating aquaculture systems: A review

In recent years,government investments in implementing restrictive public policies on the treatment and discharge of effluents from the aquaculture industry have increased.Hence,efficient and cleaner methods for aquaculture production are needed.Recirculating aquaculture systems(RAS)offers water conservation by recycling the treated aquaculture water for reuse.RAS wastewater treatment using a moving bed bioreactors(MBBRs)process has been considered well suited for maintaining good water quality,thereby making fish farming more sustainable.Currently,improvements were achieved in tackling the influence of salinity,organic matter,disinfectant,and bioreactor start-up process on the MBBR performance efficiency.This review highlights an updated overview of recent development made using MBBR to treat the residual water from RAS.Precisely,nitrification and simultaneous nitrification-denitrification(SND),and other hybrid processes for nitrogen removal were elucidated.Finally,future challenges and prospects of MBBRs in RAS facilities that need to be considered were also proposed.