Ammonia Removal Research Articles

Oxide Glasses for Removal of Ammonia and Nitrogen Derivatives from Industrial Wastewater

Adsorption is a rapid and known method to treat wastewater and remove contaminants such as ammonia (NH3+) and nitrogen derivatives. Herein, novel adsorption materials are demonstrated to eliminate the most hazard industrial and municipal contaminants including ammonia and nitrogen derivatives. Oxide glasses as new adsorbing media are beneficial for wastewater treatment due to dangling bond defects and non-bridging oxygen, which act as adsorption centers. Oxide glasses are characterized by their low cost and simple preparation method. Different types of oxide glasses including borate, phosphate, silicate, and germinate glasses are used as adsorbents to estimate the glass type of the optimal removal efficiency. It is found that the higher removal efficiency is exhibited for both borate and silicate glasses. Therefore, by preparing hybrid borate-silicate (borosilicate) glass, the best efficiency is achieved. The influences of boundary conditions including contact time, adsorption temperature, and adsorbent dosage on the efficiency of adsorption process are demonstrated. The optimal removal efficiency is achieved when using borosilicate glass sample (as adsorbent) with contact time of 90 min, adsorption temperature of 70 °C, and adsorbent dosage of 1.5 mg/100 ml. Finally, by comparing our results with the previous adsorption treatment works, it is found that adsorption capacity of ammonia reached to 9.12 mg/g, which is a valid and acceptable value.

Enhanced biological phosphorus removal from wastewater and dynamics of microbial population in dual PAOs symbiosis system

Low level of volatile fatty acids (VFAs) is a key factor limiting the performance of enhanced biological phosphorus removal (EBPR) by traditional polyphosphate accumulating organisms (PAOs). A newly discovered PAOs capable of fermenting macromolecular organic matter into short-chain VFAs could solve the problem. However, the roles of traditional and fermented PAOs in wastewater treatment processes and the collaboration between functional microorganisms remain unknown. In this study, a sequencing batch reactor (SBR) was operated with alternating anaerobic oxic (An/O) mode to investigate the effect of mixed carbon source ratios, namely, acetate (NaAc):casein hydrolysate (Cas aa) = 4:0, 3:1, 1:1, 1:3 and 0:4, on EBPR performance and microbial community structure. The results showed that the phosphorus removal efficiency remained stable as NaAc was the sole carbon source. When NaAc:Cas aa varied from 3:1 to 1:3, the recovery of system performance took less time compared to the last Run, implying an adaptation of PAOs to Cas aa. Moreover, the anaerobic phosphorus release time was found to increase with the increasing amount of VFAs from Cas aa degradation, indicating the enrichment of fermented bacteria and the utilization of VFAs by traditional PAOs. Increasing the dose of Cas aa also generated more NH4+-N, owing to the reaction of the groups in the amino acids with water, causing a drastic decrease of ammonium removal efficiency from 88.9 % to 15.2 %. The ideal process performance implied that EBPR by dual PAOs synergistic symbiosis occurred in the system with NaAc:Cas aa = 1:1. Meanwhile, the results of 16S ribosomal RNA (16S rRNA) genes-Illumina MiSeq high-throughput sequencing showed that the abundance of traditional PAOs decreased from 22.4 % (4:0) to 11.6 % (1:1) and to 4.9 % (0:4), but fermented PAOs increased from 9.9 % to 19.5 %, then decreased to 17.3 %. Dual PAOs synergistic symbiosis could be of great potential for EBPR in treating low VFAs wastewater.

An integrated novel plasma-microalgae approach for landfill leachate treatment using a high-ammonia tolerant strain of Chlorella vulgaris

Landfilling is the most common method worldwide to deal with the produced municipal solid wastes (MSW). Nonetheless, one major drawback of landfilling is the production of landfill leachate (LL). Various methods for LL treatment exist which can mainly be divided into biological and physical-chemical methods, however integrating both approaches result in more effective treatment. In this study, an indigenous Chlorella vulgaris was isolated from a landfill leachate treatment site, purified, and genetically identified for leachate treatment purposes. One replicate, C.V.M* (CCAP 211/141), of the tested Chlorella vulgaris showed an outstanding growth in 20 % LL (v/v) with a significant ammonia removal (p < 0.05). To confirm these findings, both of the Chlorella vulgaris replicates (C.V.M* and C.V.N) were further tested in 20 % LL (v/v). A dramatic increase in the growth of C.V.M* by 19-fold over its peer C.V.N with a 75 % ammonia removal (starting from concentration 290.73 mg/L) was observed. This percentage is further improved when injecting plasma activated microbubbles as a pre-treatment step. The plasma pre-treatment resulted in LL decolourisation after 3 h and reduced ammonia-N concentration by 1.9-fold. C.V.M* showed the highest growth in 20 % LL pre-treated by plasma compared to the untreated LL with a final biomass yield of 0.38 g/L, increase in the total ammonia-N removal (79 %) and a significant decrease in the pH value (8.6–6.67). Whole genome sequencing for both replicates revealed differences in genotypes between them which might indicate the possibility of a developed mutation or sexual reproduction that might have increased the ability of replicate/strain C.V.M* to tolerate harsher conditions and higher ammonia-N concentrations in 20 % diluted LL. These results might pave the way for a possible powerful candidate in LL treatment using a high-ammonia tolerant algal strain which when coupled with plasma pre-treatment might provide an effective, eco-friendly, and sustainable LL treatment approach.

Oxygen affinity and light intensity induced robust phosphorus removal and fragile ammonia removal in a non-aerated bacteria-algae system

Non-aerated bacteria-algae system gaining O2 through photosynthesis presents an alternative for costly mechanical aeration. This study investigated oxygen supply and performance of nutrients removal at low and high light intensity (LL and HL). The results showed that P removal was high and robust (LL 97 ± 1.8 %, HL 95 % ± 2.9 %), while NH4+-N removal fluctuated dramatically (LL 66 ± 14.7 %, HL 84 ± 8.6 %). Oxygen generated at illumination of 200 μmol m−2 s−1, 6 h was sufficient to sustain aerobic phase for 2.25 g/L MLSS. However, O2 produced by algae was preferentially captured in the order of heterotrophic bacteria (HB), ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB). Oxygen affinity coupled with light intensity led to NOB suppression with stable nitrite accumulation ratio of 57 %. Free nitrous acid (FNA) and light stimulated the abundance of denitrifying polyphosphate accumulating organism (DPAO) of Flavobacterium, but with declined P-accumulating metabolism (PAM) of P release, P/C, K/P and Mg/P ratios. Flavobacterium and cyanobacteria Leptolyngbya, along with biologically induced CaP in extracellular polymeric substances was the key to robust P removal. AOB of Ellin6067 and DPAO of Flavobacteria offer a promising scenario for partial nitrification-denitrifying phosphorus removal.

The microbiome of two strategies for ammonia removal with the sequencing batch moving bed biofilm reactor treating cheese production wastewater.

Cheese production facilities must abide by sewage discharge bylaws that prevent overloading municipal water resource recovery facilities, eutrophication, and toxicity to aquatic life. Compact treatment systems can permit on-site treatment of cheese production wastewater; however, competition between heterotrophs and nitrifiers impedes the implementation of the sequencing batch moving bed biofilm reactor (SB-MBBR) for nitrification from high-carbon wastewaters. This study demonstrates that a single SB-MBBR is not feasible for nitrification when operated with anerobic and aerobic cycling for carbon and phosphorous removal from cheese production wastewater, as nitrification does not occur in a single reactor. Thus, two reactors in series are recommended to achieve nitrification from cheese production wastewater in SB-MBBRs. These findings can be applied to pilot and full-scale SB-MBBR operations. By demonstrating the potential to implement partial nitrification in the SB-MBBR system, this study presents the possibility of implementing partial nitrification in the SB-MBBR, resulting in the potential for more sustainable treatment of nitrogen from cheese production wastewater.

Upcycling of used ceramic membrane as media in upflow biological reactor treating low strength wastewater

This work investigates the feasibility of media prepared from used (fouled) ceramic membrane (CM) in an upflow biological reactor (UBR) treating synthetic low strength wastewater (chemical oxygen demand, COD ∼ 200 mg/L) representative of an urban drain. The UBR was operated over 163 days at different hydraulic retention times (HRTs) of 48 h, 36 h, 24 h, 12 h and 6 h with corresponding upflow velocity between 0.06 m/d and 0.45 m/d. The COD removal was comparable at HRTs between 48 h and 12 h i.e., 83.4 ± 5.2 % (48 h), 80.5 ± 7.5 % (24 h), 76.2 ± 6.7 % (36 h) and 84.7 ± 7.2 % (12 h), followed by a marginal drop at 6 h HRT (69.9 ± 5.6 %). Ammonia removal was observed at HRTs of 48 h (37.6 ± 24.3 %) and 36 h (50.1 ± 20 %) only. Phosphate followed the same trend with removal observed at higher HRTs alone: 48 h (28.9 ± 12.5 %), 36 h (33.2 ± 8.7 %) and 24 h (23 ± 26.8 %). Total suspended solids (TSS) in the treated effluent was the lowest at 12 h HRT (6.2 mg/L). Only ∼ 3 % reduction in media porosity was observed after 163 days of operation. Overall, this media showed the recycling potential of fouled CM in a biological wastewater treatment system.

Enhanced simultaneous removal of phosphate and ammonium from swine wastewater using magnetic magnesium–loaded Chinese herbal medicine residues: Performance, mechanism, and resource utilization

Magnetic magnesium (Mg)–loaded Chinese herbal medicine residues (MM–TCMRs) were fabricated to simultaneously remove and recover phosphate and ammonium from wastewater. The MM–TCMRs exhibited larger specific surfaces and rougher structures with massive spherical particles than those of original residues. They could be separated by adjusting the magnetic field. The phosphate and ammonium adsorption by MM–TCMRs were matched with the pseudo–second–order model, while the Langmuir model yielded the maximum adsorption capacities of 635.35 and 615.57 mg g−1, respectively. Struvite precipitation on the MM–TCMRs surface was the primary removal mechanism with electrostatic attraction, ligand exchange, intra–particle diffusion, and ion exchange also involved. The recyclability of MM–TCMRs confirmed their good structural stability. More importantly, the nutrient–loaded MM–TCMRs enhanced alfalfa growth and improved soil fertility in planting experiments. Collectively, the MM–TCMRs are promising candidates for nutrient removal and recovery from wastewater.

Multidrug-resistant plasmid RP4 inhibits the nitrogen removal capacity of ammonia-oxidizing archaea, ammonia-oxidizing bacteria, and comammox in activated sludge

In wastewater treatment plants (WWTPs), ammonia oxidation is primarily carried out by three types of ammonia oxidation microorganisms (AOMs): ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and comammox (CMX). Antibiotic resistance genes (ARGs), which pose an important public health concern, have been identified at every stage of wastewater treatment. However, few studies have focused on the impact of ARGs on ammonia removal performance. Therefore, our study sought to investigate the effect of the representative multidrug-resistant plasmid RP4 on the functional microorganisms involved in ammonia oxidation. Using an inhibitor-based method, we first evaluated the contributions of AOA, AOB, and CMX to ammonia oxidation in activated sludge, which were determined to be 13.7%, 41.1%, and 39.1%, respectively. The inhibitory effects of C2H2, C8H14, and 3,4-dimethylpyrazole phosphate (DMPP) were then validated by qPCR. After adding donor strains to the sludge, fluorescence in situ hybridization (FISH) imaging analysis demonstrated the co-localization of RP4 plasmids and all three AOMs, thus confirming the horizontal gene transfer (HGT) of the RP4 plasmid among these microorganisms. Significant inhibitory effects of the RP4 plasmid on the ammonia nitrogen consumption of AOA, AOB, and CMX were also observed, with inhibition rates of 39.7%, 36.2%, and 49.7%, respectively. Moreover, amoA expression in AOB and CMX was variably inhibited by the RP4 plasmid, whereas AOA amoA expression was not inhibited. These results demonstrate the adverse environmental effects of the RP4 plasmid and provide indirect evidence supporting plasmid-mediated conjugation transfer from bacteria to archaea.

Characterization of simultaneous ammonium and nitrate removal and microbial communities in airlift reactor using 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) as carbon source and biofilm carrier

As a novel trend, solid carbon sources are applied to act as electron donors and biofilm carrier in biological denitrification process. In this study, simultaneous nitrate and ammonium removal process in an airlift sequencing batch reactor using 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) as carbon source and biofilm carrier under intermittent aeration conditions was established to treat effluent of synthetic marine recirculating aquaculture system. The results showed that maximum nitrate and ammonia nitrogen removal rates of 0.45 and 0.09 kg m−3 d−1 were achieved. No significant nitrite accumulation was found during 200-day operation, while effluent dissolved organic carbon accumulation and particle size reduction significantly increased. Microbial community analysis and batch tests illuminate that the generated sludge and attached biofilm played important roles in nitrogen removal. This study demonstrates the potential mechanism for the nitrogen removal process mediated by 3-hydroxybutyrate-co-3-hydroxyvalerate and provide a new idea for the alternative solutions of solid carbon sources.

Multifunctional photocatalytic membrane distillation for treatment of hypersaline produced water using hydrophobically modified tubular ceramic membranes

Produced water (PW) is the subsurface water brought to the surface during oil and gas production. PW is primarily disposed of by deep well injection, but it can be treated for beneficial use applications. However, efficient technologies for treating hypersaline PW with complex water chemistry are limited. This study developed an innovative, multifunctional photocatalytic membrane distillation (PMD) technology using hydrophobically modified tubular ceramic membranes coated with TiO2 nanoparticles as photocatalysts for treating unconventional PW. The effects of membrane modifications were characterized in terms of membrane morphology, pore size, chemical functionality, zeta potential, hydrophobicity, liquid entry pressure, water production, permeate water quality, and membrane fouling and scaling propensity. The desalination performance of the PMD technology was demonstrated using unconventional PW with total dissolved solids concentrations of 135,000 mg/L and 175,000 mg/L, and NH3-N concentrations of 1551 mg/L and 613 mg/L, respectively. The novel PMD concept provides a promising technology for hypersaline PW treatment, and TiO2 coating significantly reduced membrane fouling and scaling, improved distillate quality, and maintained stable permeate flux. The photocatalyst activation by ultraviolet-light emitting diodes (UV-LED) light further increased the permeate flux and enhanced the total organic carbon removal from 82.0% (without UV-LED) to 89.7% (with UV-LED). UV-LED irradiation did not affect ammonia and metals removal in PMD, reaching 99.4% and > 99.99% removal, respectively.

Electricity-driven microbial protein production: Effect of current density on biomass growth and nitrogen assimilation

Conventional agro-systems are characterised by low nitrogen conversion efficiencies, primarily due to excessive loads and limited plant nitrogen assimilation into grains by plants. Therefore, it is crucial to explore technologies that can achieve higher nitrogen assimilation efficiencies in food production. This study shows the development of a sustainable bioelectrochemical platform for ammonium recovery and upgrading into bacterial protein-rich biomass. Electrochemically-assisted batch fermenters were operated in galvanostatic mode to examine the impact of current density (0.0 – 1.0 mA·cm−2) on bacterial growth. The results revealed a linear increase in volumetric biomass productivity rate with the increment in current density. At the high current densities tested (1.0 mA·cm−2), the more elevated growth and ammonium removal rates were achieved (473 ± 164 mgTSS·L−1·d−1 and 93 ± 39 mgN·L−1·d−1, respectively). Adjusting the current density allowed for the production of biomass with high hydrogen (H2) and nitrogen yields, indicating the influence of H2 availability on these values (up to 2.6 gTSS·gH2−1 and 6.9 gTSS·gN−1, respectively). This study confirms the potential of the electro-microbial platform in recovering and transforming nutrients, particularly nitrogen, into microbial biomass that can be utilised as edible protein or organic fertiliser. The findings highlight the viability of this approach for achieving efficient nitrogen assimilation and biomass production, offering promising prospects for addressing nitrogen utilisation challenges in conventional agro-systems.

Removal of ammonium by‐products produced during biocementation soil improvement using rinse injection strategies

AbstractBio‐mediated soil improvement technologies leverage microbial enzymatic and metabolic processes to generate minerals, gases and biopolymers that can improve soil engineering behaviours with the potential to reduce detrimental environmental impacts when compared with conventional methods. Ureolytic biocementation is perhaps the most widely researched of these processes and relies on urea hydrolysis in the presence of calcium to initiate the precipitation of calcium carbonate minerals on soil particle surfaces and contacts, thereby improving soil behaviours. Although effective, urea hydrolysis generates aqueous ammonium by‐products that may result in undesirable environmental and human health impacts, if left unaddressed. Recent studies have shown the potential of rinse solution injections to effectively remove generated ammonium following biocementation through both advective flow and the removal of sorbed ammonium from soil surfaces; however, critical gaps remain in our understanding of the effect of rinse solution composition and injection strategies on ammonium removal efficacy. In this study, 16 soil column experiments were performed to investigate the effect of rinse solution cation types, cation concentrations, applied injection sequences and biocementation treatment variations on the removal of ammonium from a biocemented poorly graded sand. All columns receiving cation‐enriched rinse solutions achieved greater than 98% aqueous, 65% sorbed and 95% total ammonium removal after injecting 12 pore volumes, with no detectable impacts on cementation integrity. Cation‐enriched solutions specifically enhanced sorbed ammonium removal and achieved sorbed ammonium concentrations up to 2 orders of magnitude less than those observed in columns rinsed with deionized water alone. Columns receiving K+‐based rinse solutions and 12 daily 1‐PV rinse injections also achieved greater total ammonium removal when compared with comparable columns receiving rinse solutions containing other cations and continuous 12‐PV rinse injections.

Performance of a modified and intermittently operated slow sand filter with two different mediums in removing turbidity, ammonia, and phosphate with varying acclimatization periods

The present study investigated the utilization of blood clam shells as a potential substitute for conventional media, as well as the influence of the acclimation time on the efficacy of an intermittent slow sand filter (ISSF) in the treatment of real domestic wastewater. ISSF was operated with 16 h on and 8 h off, focusing on the parameters of turbidity, ammonia, and phosphate. Two media combinations (only blood clam shells [CC] and sand + blood clam shells [SC]) were operated under two different acclimatization periods (14 and 28 d). Results showed that SC medium exhibited significantly higher removal of turbidity (p < 0.05) as compared to CC medium (45.99 ± 26.84 % vs. 3.79 ± 9.35 %), while CC exhibited slightly higher (p > 0.05) removal of ammonia (23.12 ± 20.2 % vs. 16.77 ± 16.8 %) and phosphate (18.03 ± 11.96 % vs 13.48 ± 12 %). Comparing the acclimatization periods, the 28 d of acclimatization period showed higher overall performances than the 14 d. Further optimizations need to be conducted to obtain an effluent value below the national permissible limit, since the ammonia and phosphate parameters are still slightly higher. SEM analysis confirmed the formation of biofilm on both mediums after 28 d of acclimatization; with further analysis of schmutzdecke formation need to be carried out to enrich the results.

Electrically-assisted anaerobic digestion under ammonia stress: Facilitating propionate oxidation and activating methanogenesis via direct interspecies electron transfer

Electrical assistance is an effective strategy for promoting anaerobic digestion (AD) under ammonia stress. However, the underlying mechanism of electrical assistance affecting AD is insufficiently understood. Here, electrical assistance to AD under 5 g N/L ammonia stress was provided, by employing a 0.6 V voltage to the carbon electrodes. The results demonstrated remarkable enhancements in methane production (104.6 %) and the maximal methane production rate (207.7 %). The critical segment facilitated by electro-stimulation was the microbial metabolism of propionate-to-methane, rather than ammonia removal. Proteins in extracellular polymer substances were enriched, boosting microbial resilience to ammonia intrusion. Concurrently, the promoted humic/fulvic-substances amplified the microbial electron transfer capacity. Metagenomics analysis identified the upsurge of propionate oxidation at the anode (by e.g. unclassified_c__Bacteroidia), and the stimulations of acetoclastic and direct interspecies electron transfer-dependent CO2-reducing methanogenesis at the cathode (by e.g. Methanothrix). This study provides novel insights into the effect of electrical assistance on ammonia-stressed AD.

Simultaneous and efficient removal of ammonium and nitrate by a novel isolated Agrobacterium tumefaciens M

A novel nitrogen removal strain M, was isolated and identified as Agrobacterium tumefaciens M. Strain M could remove 100% and 99% of 100 mg/L ammonium and nitrate mainly through assimilation, with elimination rates of 8.61 and 4.60 mg/L/h, respectively. The optimal growth and nitrogen elimination conditions were obtained by a single-factor experiment, including a shaking speed of 150 rpm, pH of 7, C/N ratio of 15, and carbon supply of sucrose (ammonium) and sodium citrate (nitrate). Key genes involved in nitrogen metabolism, including napAB, nirK, norBC, nosZ, nirBD, glnA, and nasAB, were identified in strain M. Moreover, strain M exhibited excellent nitrogen removal efficiencies higher than 90% when ammonium and nitrate coexisted. All results indicated that strain M shows great nitrogen removal potential.

Wastewater Treatment System Optimization for Sustainable Operation of the SHARON–Anammox Process under Varying Carbon/Nitrogen Loadings

Partial nitritation (PN) coupled with the anaerobic ammonium oxidation (Anammox) process has improved ammonium removal in wastewater treatment plants (WWTPs). The operation conditions of this process, i.e., the dissolved oxygen (DO) and the influent ammonium and nitrite concentrations, drive the process to an equilibrium to suppress nitrite-oxidizing bacteria and achieve a proper nitrite over ammonium (NO2/NH4) ratio. This study aimed to implement a set of control strategies in a WWTP model BSM2-SHAMX, combining PN in a single reactor system for high-activity ammonia removal over nitrite (SHARON) to an Anammox reactor, using proportional–integrative–derivative (PID) control and model predictive control (MPC) in a cascade. For correct coupling, the PN should maintain an output NO2/NH4 ratio between 1 and 1.3, suitable for the Anammox process. In the cascade controller feedback loop, the primary control loop controls the NO2/NH4 ratio through the DO concentration from the secondary control loop, which guarantees better effluent nitrogen removal. The performance of the plant was assessed by evaluating the control strategies with different influent carbon/nitrogen (C/N) loadings. The study results showed that the MPC controllers provided better results, with an improvement of 36% in the operational cost compared to the base case with a cost around 26,000 EUR/d, and better nitrogen removal surpassing 90% removal, 10% more than the base case.

Efficient Ammonia Removal in the Rosetta Branch of the River Nile using Activated Carbon: A Comprehensive Study

Efficient Ammonia Removal in the Rosetta Branch of the River Nile using Activated Carbon: A Comprehensive Study

Rapid start-up of the biofilter for simultaneous manganese and ammonia removal at low temperature: Effects of phosphate and copper

In low-temperature environments, low nutrients such as inorganic salts limiting microbial proliferation further extended the start-up period of biofilters for drinking water treatment. This study explored the ammonia and manganese (Mn) removal performance and the relevant mechanisms under single and combined PO43− at 30 μg/L and Cu2+ at 10 μg/L. The start-up periods of R0 (control), R1 (Cu2+ single), R2 (PO43− single) and R3 (combined Cu2+ and PO43−) were 98, 82, 32 and 24 days, respectively. PO43− increased the concentration of extracellular polymeric substances (EPS) by stimulating cellular metabolism, which promoted the formation of biofilm. Additionally, the combined Cu2+ and PO43− significantly promoted the ammonia monooxygenase (AMO) and nitrite oxidoreductase (NXR) activities, which further facilitated the removal of ammonia. The combined Cu2+ and PO43− accelerated the conversion of NH4+-N to NO2−-N and NO2−-N to NO3−-N processes thereby reducing the inhibition of Mn removal by NH4+-N and NO2−-N, and the kinetics of biological manganese oxidation showed that the combined Cu2+ and PO43− increased the rate of Mn removal, which both promoted the Mn removal in the biofilters. Furthermore, the combined Cu2+ and PO43− supported the proliferation of functional microorganisms. In summary, the synergistic effect of Cu2+ and PO43− enhanced the Mn and ammonia removal performance and achieved rapid start-up of the biofilter at low temperatures.

Removal of iron, manganese and ammonium from contaminated mine water by biochar immobilized Acinetobacter sp. AL-6 under acid condition, and the role of extracellular polymeric substances

In acidic mine wastewater, Mn and Fe are among the prime heavy metals and pose a great threat to the ecological environment and human health. Combining biological and physical methods to treat heavy metal contaminated water bodies is a promising remediation technique. In this study, grapefruit peel biochar immobilized Acinetobacter sp. AL-6 (co-system) was applied to treat the contaminated water with co-existing Mn2+, Fe2+ and NH4+-N. The results showed that almost 100% of Mn2+, Fe2+, Zn2+ and Cu2+ were removed in bioreactor, and was transferred to Mn2+, Fe3+, Zn2+ and Cu2+ precipitates on the surface of co-system without N2O accumulation. Especially, Mn2+ and Fe2+ were adsorbed in extracellular polymers (EPS) of strain AL-6. The present study mainly confirmed that the combined system of biochar and bacteria had great potential in the complex water removal of multiple heavy metals and NH4+-N, and also revealed the regulation of heavy metals by the EPS of strain.

Utilizing Coffee Husk Biochar as an Effective Adsorbent for Ammonium Removal in Groundwater

The study investigated the performance of a novel biochar derived from coffee husks (BCFH) and its alkaline-activated product (BCFH-NaOH) for ammonium removal in the aqueous solution. Several batch experiments were conducted with the synthetic solution to determine the adsorption properties of the biochars. At the initial ammonium concentration of 50 mg/L, the optimal dosage for both materials was 10 g/L, while the ideal pH range was 4-9. The equilibration adsorption time on both materials is within 30 minutes, indicating their high practical applicability. Both the pseudo-first order and pseudo-second order kinetic were applied successfully to describe the adsorption kinetics (R2 &gt;0.95). The isotherms can be defined by both Langmuir and Freundlich models, showing that ammonium removal by biochars is a complex process. BCFH-NaOH showed better performance, with the maximum adsorption capacity reaching 9.97 mg-NH4/g, compared to 6.64 mg-NH4/g of BFCH. Finally, BCFH-NaOH was tested with a practical groundwater sample (Co = 11.5 mg-NH4/L), achieving a sorption efficiency of up to 80 % while eliminating most of the hardness. These results show that the modified coffee husk biochar could be applied as a low-cost, environmentally friendly adsorbent for ammonium removal.