High Concentration Of Ammonia Nitrogen Research Articles

Preliminary investigation on the causes of red tides in Qinhuangdao coastal areas in 2022.

To explore the causes of red tides in Qinhuangdao coastal water, we conducted surveys on both water quality and red tides during April to September of 2022 and analyzed the relationships between main environmental factors and red tide organisms through the factor analysis and canonical correspondence analysis. The results showed that there were eight red tides along the coast of Qinhuangdao in 2022, with a cumulative blooming area of 716.1 km2. The red tides could be divided into three kinds based on the major blooming organisms and occurrence time, Noctiluca scintillans bloom, diatom-euglena (Skeletonema costatum, Eutreptiella gymnastica, Pseudo-nitzschia spp.) bloom, and dinoflagellate (Scrippsiella trochoidea and Ceratium furca) bloom. Seasonal factor played roles mainly during July to September, while inorganic nutrients including nitrogen and phosphorus influenced the blooms mainly in April and July. The canonical correspondence analysis suggested that N. scintillans preferred low temperature, and often bloomed with high concentrations of ammonium nitrogen and dissolved inorganic phosphorus. S. costatum, E. gymnastica, and Pseudo-nitzschia spp. could tolerate broad ranges of various environmental factors, but favored high temperature and nitrogen-rich seawater. C. furca and S. trochoidea had higher survival rate and competitiveness in phosphate-poor waters. Combined the results from both analyses, we concluded that the causes for the three kinds of red tide processes in Qinhuangdao coastal areas in 2022 were different. Adequate diet algae and appropriate water temperature were important factors triggering and maintaining the N. scintillans bloom. Suitable temperature, salinity and eutrophication were the main reasons for the diatom-euglena bloom. The abundant nutrients and seawater disturbance promoted the germination of S. trochoidea cysts, while phosphorus limitation caused the blooming organism switched to C. furca and maintained the bloom hereafter.

Recovery of ammonia nitrogen and phosphate from livestock farm wastewater by iron-magnesium oxide coupled lignite and its potential for resource utilization.

A new adsorbent called iron-magnesium oxide coupled lignite (CIMBC) was developed to address the challenges of recovering high concentrations of ammonia nitrogen and phosphate in livestock farm wastewater and improving the inefficient use of lignite (BC) with low calorific value. CIMBC was synthesized using the modified ferromagnesium salt double-coating method. The experiments demonstrated that Fe2O3 and MgO could be effectively loaded onto the surface of BC at a Fe/Mg molar ratio of 1:2 and pyrolysis temperature of 500°C. The optimal conditions for adsorption were determined to be an N/P concentration ratio of 2:1, adsorbent dosage of 1g/L, and pH of 7. The presence of coexisting cations (Ca2+ and Mg2+) inhibited the removal of ammonia nitrogen but enhanced the removal of phosphate. Likewise, the presence of coexisting anions (CO32- and SO42-) hindered the removal of both ammonia nitrogen and phosphate. The adsorption behavior followed the pseudo-second-order model and the Langmuir model, with a maximum adsorption capacity of 95.69mg N/g for ammonia nitrogen and 101.32mg P/g for phosphate. The adsorption process was a spontaneous endothermic process controlled by multiple levels. The main mechanisms of adsorption involved electrostatic attraction, intra-particle diffusion, ion exchange, chemical precipitation, and coordination exchange. After 5 times of adsorption-desorption, the recovery rate of CIMBC is less than 50%, and the removal rate of phosphate is less than 40%. Although the RCIMBC exhibited low reusability, but also it showed potential in removing heavy metals (Pb) from wastewater and for use as a slow-release fertilizer. CIMBC is a promising new adsorbent, which can realize resource utilization of lignite with low calorific value while removing nitrogen and phosphorus.

High efficiency and stable partial nitration achieved via gel immobilization

Long-term high efficiency and stable partial nitrification (PN) performance was achieved using gel-immobilized partial nitrifying bacteria. The PN characteristics of the filler under high and low ammonia nitrogen concentrations and low temperature were comprehensively studied and the rapid reactivation was achieved after reactor breakdown or long stagnation period. The results showed that the maximum ammonia oxidation rate was 66.8 mg•(L•h)−1 and the nitrite accumulation rate was above 95 % for the filler. Efficient and stable PN performance depends on the high abundance of ammonia-oxidizing bacteria (AOB) inside the filler and dynamically microbial community. In addition, the oxygen-limited zone and competition between the microorganisms inside the filler effectively inhibited the growth of nitrite oxidizing bacteria, and the sludge outside the filler assisted in this process, which supported the dominant position of AOB in fillers. This study provides a reliable technology for the practical application of the PN nitrogen removal process.

Research progress of leachate treatment in waste transfer station

The garbage leachate generated by the waste transfer station has the characteristics of scattered water sources, relatively small water quantity, large fluctuations in water quality and quantity, and high concentrations of organic matter, ammonia nitrogen, suspended solids, and other pollutants. These characteristics make it prone to environmental hazards. This paper analyzes the characteristics and hazards of leachate from waste transfer stations and introduces the current research status of physico-chemical, biological, and combined treatment of leachate from waste transfer stations. Meanwhile, this paper introduces engineering practices for leachate treatment in waste transfer stations, offering a valuable reference for research and engineering practices in this field. Finally, this review discusses pretreatment, economic, low-carbon, and high-efficiency treatment methods and facilities, the recovery of valuable elements, energy recycling technologies, and the demand outlook for high-standard deep treatment processes.

Influence of Mesophilic Bacteria Inoculation with Chicken Manure for Biogas Production Enhancement in Anaerobic Digestion (AD) Process

The objective of this study is to investigate biogas production by anaerobic digestion using mesophilic bacteria mixed with Palm Oil Mill Effluent (POME). This project aims to determine the volume of biogas generation and volatile fatty acid (VFA) production from chicken manure via the anaerobic digestion process. Anaerobic digestion (AD) of chicken manure (CM) often faces obstacles, including high total ammonia nitrogen (TAN) concentration, inorganic soil particles, and wood chips. The digestion process was carried under batch mode conditions in Scott bottles of 1.0 L active volume. The bottles were immersed in a water bath to control their temperature at 37℃. The characteristics of total solid, volatile solid of mass fraction, pH, and temperature on the amount of biogas produced were studied. The investigation showed that biogas production can be enhanced by inoculation of another material. The optimum biogas composition in the AD system was recorded by Inoculum I, which was achieved on Day 2 at 560 mL/L. The highest cumulative methane yield was observed in the leachate with Inoculum (I), which was 8976 mL/gVS, while the CML produced 4 mL/g VS. The anaerobic digestion (AD) process augmented with inoculum demonstrated heightened efficacy in biogas generation and VFA concentration reduction during the acidogenic phase, surpassing the observed performance in chicken manure leachate.

Performance and mechanism of Al, N co-doped carbon/nano-TiO2 photocatalytic oxidation for the removal of ammonia nitrogen and Ni/Co complexes from ternary precursor wastewater

The process of producing ternary precursors for new lithium batteries produces industrial wastewater containing high concentrations of ammonia nitrogen and metal ammonia complexes, which requires strict treatment. In this study, a simple and efficient photocatalyst (Al, N co-doped carbon/nano-TiO2) with excellent adsorption and photocatalytic properties was developed. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption–desorption test, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), which indicated that the catalyst had excellent specific surface area and strong light absorption properties. In addition, the performance of photocatalytic treatment of ternary precursor wastewater was investigated by varying the amount of Al doping, the loading of nano-TiO2, the amount of catalyst input, changing the adsorption and photocatalytic time. The results suggested that the 3.0 g/L of Al, N co-doped carbon/nano-TiO2 composite photocatalyst achieved 91.45% degradation efficiency of ammonia nitrogen and the removal efficiency of nickel and cobalt was 99.11% and 98.34%, respectively. EDS and XPS analyses showed that ammonia nitrogen pollutants in the wastewater were eventually degraded to nitrogen and nitrogen oxides, with nickel and cobalt adsorbed on the catalyst surface in the form of Ni2+ and Co2+.

Nitrogen and phosphorus recovery from hemodialysis wastewater to use as an agricultural fertilizer

IntroductionHemodialysis wastewater contains high concentrations of ammonia nitrogen and phosphorus. Recovery of these nutrients as soil fertilizers represents an interesting opportunity to ensure a sustainable fertilizer supply. MethodsIn this paper, a simple method for recovering phosphorous and nitrogen as crystalline struvite [MgNH4PO4·6H2O] is presented. An integrated cost model is also presented in order to create a positive business case. ResultsRecovery rates in form of struvite of 95% of PO43−-P and 23% of NH4+-N were achieved with a profit. ConclusionTo the best of our knowledge, this paper is the first to study the recovery of these naturally occurring minerals from hemodialysis wastewater. This offers great potential for the valorization of this type of wastewater.

Enhanced Treatment of Potato Starch Wastewater Using Chitosan-Modified Biochar Film Adsorption Coupled with Ultrafiltration

Potato starch wastewater, a byproduct of potato processing, is an escalating environmental concern due to its high concentrations of COD (chemical oxygen demand), ammonia nitrogen, and total phosphorus (TP). Addressing this challenge, this research introduced a novel method combining chitosan-modified biochar film (CBC) adsorption with subsequent ultrafiltration. SEM (scanning electron microscope), FTIR (Fourier transform infrared spectral), XRD (X-ray diffractometer), and BET (specific surface area) analyses validated CBC’s enhanced surface characteristics, confirming successful chitosan (CS) film impregnation. CBC exhibited superior adsorption capacities, especially 40%wt-CBC, optimizing COD removal at 79.8%, ammonia nitrogen at 93.3%, and TP at 91.2%. Kinetic studies associated the adsorption process with a pseudo-second-order model, highlighting chemical adsorption. Additionally, the Langmuir isotherm model suggested monolayer adsorption with no inter-adsorbate interactions. The treated effluent, post adsorption, was directed through an ultrafiltration membrane, ensuring water quality suitable for reuse. This integrative treatment not only offers an effective solution for potato starch wastewater management but also underscores the potential for sustainable water resource recovery in the food processing sector.

Simultaneous nitrification/denitrification in a single-chamber stainless steel bioelectrochemical reactor

The removal of nitrogen from wastewater with a low C/N ratio often requires additional carbon sources to address the shortage of electron donors, which increases the cost. We explored a simple and energy effecient means for treating wastewater with a high concentration of ammonia nitrogen under anoxic conditions without the addition of carbon sources. We constructed a stainless steel tube as an anaerobic single-chamber microbial electrolysis cell (MEC) for investigating autotrophic simultaneous nitrification/denitrification (SND). Two different structures (carbon brush vs. stainless-steel) were used to construct biocathodes and compared their performances under different voltages (1.8 V, 1.5 V, 1.2 V) applied by DC power. When voltage was applied at 1.5 V, the removal rates of TN and NH4+-N reached 19.68 ± 0.02 mg L−1 d−1 and 21.04 ± 0.17 mg L−1 d−1, respectively. Simultaneously, it achieved maximum TN and NH4+-N removal over 14 days (44.97 ± 0.28 %, 48.16 ± 0.32 %). These rates were 1.8 and 5 times of that obtained with the conventional carbon brush electrode and open-circuit control. Furthermore, microbial community and SEM analysis indicate that species of Thermomonas, Thibacillus and Thauera were the predominant autotrophic electroactive denitrifying bacteria in the reactors. Overall, we achieved a high rate of nitrogen removal, electron utilization and energy recovery in a single-chamber stainless steel MEC.

Deep-Learning-Based Water Quality Monitoring and Early Warning Methods: A Case Study of Ammonia Nitrogen Prediction in Rivers

In line with rapid economic development and accelerated urbanization, the increasing discharge of wastewater and agricultural fertilizer usage has led to a gradual rise in ammonia nitrogen levels in rivers. High concentrations of ammonia nitrogen pose a significant challenge, causing eutrophication and adversely affecting the aquatic ecosystems and sustainable utilization of water resources. Traditional ammonia nitrogen detection methods suffer from limitations such as cumbersome sample handling and analysis, low sensitivity, and lack of real-time and dynamic feedback. In contrast, automated monitoring and ammonia nitrogen prediction technologies offer more efficient methods and accurate solutions. However, existing approaches still have some shortcomings, including sample processing complexity, interference issues, and the absence of real-time and dynamic information feedback. Consequently, deep learning techniques have emerged as promising methods to address these challenges. In this paper, we propose the application of a neural network model based on Long Short-Term Memory (LSTM) to analyze and model ammonia nitrogen monitoring data, enabling high-precision prediction of ammonia nitrogen indicators. Moreover, through correlation analysis between water quality parameters and ammonia nitrogen indicators, we identify a set of key feature indicators to enhance prediction efficiency and reduce costs. Experimental validation demonstrates the potential of our proposed approach to improve the accuracy, timeliness, and precision of ammonia nitrogen monitoring and prediction, which could provide support for environmental management and water resource governance.

Enhancement of alkali- and oxidation-modified biochars derived from water hyacinth for ammonium adsorption capacity

ABSTRACT Wastewater containing high concentrations of ammonium-nitrogen (NH4 +-N) is considered a major concern because its untreated discharge has a variety of adverse effects on the environment and human health. Adsorption using biochars is an easy and cost-effective wastewater treatment method. However, aquatic plants such as water hyacinth for biochar feedstock are considered unsuitable for adsorbent use due to limited NH4 +-N adsorption capacity. In this study, biochar made from water hyacinth was modified with potassium hydroxide (KOH) and hydrogen peroxide (H2O2) to obtain highly efficient adsorbent. This study aimed to enhance NH4 +-N adsorption capacity by KOH- and H2O2-treatments and identify NH4 +-N adsorption mechanism of the modified biochars derived from water hyacinth. The NH4 +-N adsorption of all biochars was dependent on the initial solution pH increasing from pH 2 to 4, then relatively constant from pH 4 to 8. Pseudo-second-order model and Langmuir model were found to be the best fit for NH4 +-N adsorption data. The maximum NH4 +-N adsorption capacity of biochars increased about 8 times (17.1 mg g−1) and 10 times (21.5 mg g−1) after KOH- and H2O2-modification, respectively, compared to pristine biochar (2.14 mg g−1). The main NH4 +-N adsorption mechanisms were suggested as cation exchange for both biochars particularly KOH-modified biochar, and hydrogen bonding by oxygen-containing surface functional groups for H2O2-modified biochar. This study suggested that aquatic plant-based biochar, which has been considered difficult to use, had potential as a promising alternative adsorbent for removing NH4 +-N from wastewater through modification.

Visible-Light-Driven Photocatalytic Degradation of High-Concentration Ammonia Nitrogen Wastewater by Magnetic Ferrite Nanosphere Photocatalysts

In this study, magnetic CuFe2O4, MgFe2O4, and ZnFe2O4 nanosphere photocatalysts were prepared by the sol–gel method at 300 °C, 400 °C, and 500 °C, respectively (named as CF300, CF400, CF500, MF300, MF400, MF500, ZF300, ZF400, and ZF500). The characterization by X-ray diffraction (XRD) revealed that the optimal calcination temperature was 400 °C. Then, CF400, MF400, and ZF400 were used to treat high-concentration ammonia nitrogen wastewater (HCAW, 1000 mg/L) at different pH levels. The result showed that the optimal pH for CF400, MF400 and ZF400 to degrade HCAW was 9.0, and CF400 required a shorter illumination time (80 min) than MF400 and ZF400 (120 min) to completely remove ammonia nitrogen from HCAW. However, CF400 was unstable and decomposed, and a blue substance was observed during the magnetic recovery experiment. The recovery rate of ZF400 (66.7%) was higher than MF400 (53.2%) with no decomposition phenomenon, and the ammonia nitrogen removal rate of ZF400 remained above 90% after five cycles. Additionally, the ammonia nitrogen removal rate of ZF400 could reach 80.2% when the ammonia nitrogen concentration was as high as 5000 mg/L. Therefore, compared with CF400 and MF400, ZF400 was more suitable for treating HCAW.

Biosolids-Derived Biochar Improves Biomethane Production in the Anaerobic Digestion of Chicken Manure

Anaerobic digestion has attracted great interest for use in the management of organic wastes and the production of biomethane. However, this process is facing challenges, such as a high concentration of ammonia nitrogen, which affects the methanogenesis process and, thus, the production of methane. This study investigates the use of biosolid-derived biochar for mitigating ammonia stress and improving methane production during the anaerobic digestion of chicken manure, using both pristine biochar and biochar modified with a potassium hydroxide (KOH) solution. Batch mesophilic anaerobic digestion (37 °C) was carried out over 18 days. When compared to chicken-manure-only controls, a significant increase in methane formation was observed in the digesters amended with biochar and KOH-modified biochar, producing 220 L kg−1 volatile solids (VSs) and 262 L kg−1 VSs of methane, respectively, compared to 139 L kg−1 VSs from the control digesters. The use of biochar and KOH-modified biochar resulted in a significant reduction of 8 days in the lag phase. The total ammonia nitrogen (TAN) concentration was reduced in the digesters with biochar and KOH-modified biochar by 25% and 35.5%, respectively. The quantitative polymerase chain reaction (QPCR) data revealed that the number of 16S rRNA gene copies was around 50,000 and 41,000 times higher in the biochar and KOH-modified biochar digesters, respectively, compared to the control digesters on day 18. The taxonomic profiles indicated that the BC and KOH-BC digesters contained a mixture of methanogenic pathways, including acetoclastic (Methanosaetaceae), hydrogenotrophic (Methanosarcinaceae), and methylation (Methanofastidiosaceae). This mix of pathways suggests a more robust archaeal community and, hence, more efficient methanogenesis. The results show that the addition of biosolids biochar enhances anaerobic digestion, mitigates ammonia stress to methanogens, and significantly increases biogas production.

Enhanced denitrification of the AO-MBBR system used for expressway service area sewage treatment: A new perspective on decentralized wastewater treatment

Decentralized wastewater treatment warrants considerable development in numerous countries and regions. Owing to the unique characteristics of high ammonia nitrogen concentrations and low carbon/nitrogen ratio, nitrogen removal is a key challenge in treating expressway service area sewage. In this study, an anoxic/oxic-moving bed biofilm reactor (A/O-MBBR) and a traditional A/O bioreactor were continuously operated for 115 days and their outcomes were compared to investigate the enhancement effect of carriers on the total nitrogen removal (TN) for expressway service area sewage. Results revealed that A/O-MBBR required lower dissolved oxygen, exhibited higher tolerance toward harsh conditions, and demonstrated better shock load resistance than traditional A/O bioreactor. The TN removal load of A/O-MBBR reached 181.5 g‧N/(m3‧d), which was 15.24% higher than that of the A/O bioreactor. Furthermore, under load shock resistance, the TN removal load of A/O-MBBR still reached 327.0 g‧N/(m3‧d), with a TN removal efficiency of above 80%. Moreover, kinetics demonstrated that the denitrification rate of the A/O-MBBR was 121.9% higher than that of the A/O bioreactor, with the anoxic tank biofilm contributing 60.9% of the total denitrification rate. Community analysis results revealed that the genera OLB8, uncultured_f_Saprospiraceae and OLB12 were the dominant in biofilm loaded on carriers, and OLB8 was the key for enhanced denitrification. FAPROTAX and PICRUSt2 analyses confirmed that more bacteria associated with nitrogen metabolism were enriched by the A/O-MBBR carriers through full denitrification metabolic pathway and dissimilatory nitrate reduction pathway. This study offers a perspective into the development of cost-effective and high-efficiency treatment solutions for expressway service area sewage.

Preparation of magnetic ZnFe2O4 nanosphere photocatalyst for high concentration ammonia nitrogen wastewater treatment

High concentration ammonia nitrogen (NH4+-N) wastewater caused a great threat on the safety of water resources. Consider that photocatalysis is an environmentally friendly technology, which can effectively removel pollutants. Herein, magnetic ZnFe2O4 nanosphere photocatalyst was prepared by sol-gel method at a calcination temperature of 300 °C, 400 °C and 500 °C and applied in eliminating high concentration NH4+-N wastewater pollutants under economical 400 °C temperature in this study. The effect of pH on magnetic ZnFe2O4 nanosphere photocatalyst treating high concentration NH4+-N wastewater was investigated. Optimally, 100 % of the initial NH4+-N (1000 mg/L) was removed, photocatalytic rate and stripping rate were 84.9% and 15.1% respectively, and NO3--N and NO2--N were barely detected at pH of 9.0 in 120 min. The quenching experiments showed that h+ and •O2- were the key reactive species to photodegrade NH4+-N. The mechanism of high concentration NH4+-N removal were proposed. Moreover, NH4+-N removal rate of recovered magnetic ZnFe2O4 nanosphere photocatalyst by magnetic force after five cycles still remained over 90%. This study demonstrated that magnetic ZnFe2O4 nanosphere photocatalyst could be a promising catalyst for the treatment of the high concentration NH4+-N wastewater.

Enhanced treatment of sludge drying condensate by A/O-MBR process: Microbial activity and community structure

With the rapid increase of sludge production from sewage treatment plants, the treatment of sludge drying condensate rich in a large amount of pollutants urgently needs to be addressed. Due to the unique characteristics of sludge drying condensate (high ammonia nitrogen and COD concentration), there are almost no reports on biological treatment methods specifically targeting sludge drying condensate. In this study, A/O-MBR process was proposed for sludge drying condensate treatment and the effects of ammonia nitrogen loads, alkalinity and aeration intensity were explored. Experimental results show that under the ammonia nitrogen load of 0.35 kg NH4+-N/(m3·d) and the aeration intensity of 0.5 m3/(m2·min), the removal rate of COD and NH4+-N could reach 94% and 99.86% with the addition of alkalinity (m(NaHCO3): m(NH4+-N) = 7:1), respectively. The distribution of living and dead microbial cells in the activated sludge of three reactors also proved that the supplement of alkalinity in the influent can ensure the feasible living conditions for microorganisms. In addition to traditional nitrifying bacteria, through the supplementation of alkalinity and the reduction of aeration intensity, the system had also domesticated high abundance heterogeneous nitrification aerobic denitrification (HN-AD) and aerobic denitrification bacteria (both more than 10% of the total bacterial count). The denitrification process of sludge drying condensate was simplified and the denitrification efficiency was greatly improved. The findings of this study could provide important theoretical guidance for the biological treatment process of sludge drying condensate.

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

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

The effects of carbon nitrogen ratio and salinity on the treatment of swine digestion effluent simultaneously producing bioenergy by microalgae biofilm

In order to remove high concentrations of ammonia nitrogen (NH4+-N) and refractory sulfamethazine (SM2) from swine digestion effluent, different carbon/nitrogen (C/N) ratios and salinity were used to determine the effects of pollutants removal in the microalgae biofilm system. Microalgae biofilm treatment under optimal environmental conditions in synthetic swine digestion effluent were C/N ratio of 20 and salinity of 140 mM. In order to make the actual swine digestion effluent discharge up to the standard, three different two-cycle treatments (suspended microalgae, microalgae biofilm, microalgae biofilm under the optimal conditions) were studied. The results showed that after two-cycle treatment with microalgae biofilm under the optimal conditions, the actual swine digestion effluent levels of total nitrogen (TN), NH4+-N, total phosphorus (TP), chemical oxygen demand (COD), SM2 were 22.65, 9.32, 4.11, 367.28, and 0.99 mg L−1, respectively, which could satisfy the discharge standards for livestock and poultry wastewater in China. At the same time, first-order kinetic simulation equations suggested a degradation half-life of 4.85 d for SM2 under optimal conditions in microalgae biofilm, and microbial community analysis indicated that the dominant genus was Halomonas. Furthermore, 35.66% of lipid, 32.56% of protein and 18.44% of polysaccharides were harvested after two-cycle in microalgae biofilm treatment under optimal environmental conditions. These results indicated that the regulation of C/N and salinity in microalgae biofilm for the treatment of swine digestion effluent was a high-efficiency strategy to simultaneously achieve wastewater treatment and bioenergy production.

Effect of influent ammonia nitrogen concentration on the phosphorus removal process in the aerobic granular sludge reactor

The effects of different influent ammonia nitrogen (NH3-N) concentrations (stage I to IV: 20, 40, 60 and 80 mg/L) on the phosphorus (P) removal process were studied in an aerobic granular sludge (AGS) reactor under anaerobic/aerobic operating conditions. The phosphorous removal performance kept stable at first (stage I and II) and then significantly deteriorated at further increase of influent NH3-N concentration (stage III and IV). On the process of microbial metabolism, further increase of NH3-N aggravated the competition between phosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) for carbon sources in the anaerobic phase, and weakened the P absorption capacity of PAOs in the aerobic phase. Denitrifying phosphate accumulating organisms (DPAOs) showed higher resistance to the increase of NH3-N concentration than traditional PAOs. On the functional structure of the system, microorganisms related to phosphorus removal in the system were mainly enriched in the granules, while microorganisms with heterotrophic denitrifying function dominated the sludge flocs to obtain higher growth advantage at high ammonia nitrogen concentration. The results of this study provide more insight into the biological stability of AGS systems.

Pretreatment of ammonia nitrogen in industrial waste leachate by struvite crystallization method

Struvite crystallization method is used to effectively remove high concentration of ammonia nitrogen from leachate during the pretreatment stage of industrial solid waste landfill (ISWL) leachate. The effects of molar ratio of phosphorus to nitrogen (P:N), molar ratio of magnesium to nitrogen (Mg:N) and pH value on ammonia nitrogen removal were discussed. The results indicate that compared with pH adjustment later, pH adjustment first increases the removal rate of ammonia nitrogen by 30–54% . When pH value is 9.5, the removal of ammonia nitrogen reaches 82%; When P:N is 0.9 ∼ 1.1, the removal of ammonia nitrogen is maintained at 78 ∼ 82%; When Mg: N is 1.1 ∼ 1.3, the removal of ammonia nitrogen reaches 90%; When the pH value is 10 and P:N:Mg is 1.1:1:1.2, the removal rate of ammonia nitrogen reaches the highest, reaching 95.9%.