Removal Efficiencies Of NH3-N Research Articles

Microbiology community changes during the start-up and operation of a photosynthetic bacteria-membrane bioreactor for wastewater treatment

A pilot-scale photosynthetic bacteria-membrane bioreactor was applied to treat wastewater and culture photosynthetic bacteria (PSB) cells, and microbial communities at different stages were analyzed to reveal the underlying roles of efficient long-time operation of this reactor. After 40days start-up, the reactor was successfully operated for 180days. The results showed that the PSB-membrane bioreactor operated stably, with high COD and NH3-N removal efficiency of 95%. The PSB biomass could maintain a high cell concentration with a 10% harvest each day. Analysis of the microbial community showed that bacterial communities changed dramatically at different stages. The dominant bacteria were Ectothiorhodospira in the beginning to Caenispirillum and Pannonibacter during the stable operation. The Shannon index from 1.876 dropped to 1.477 after 6months. The diversity of PSB community decreased during the process. It revealed that the microbial community on the membrane was more diverse than that inside the bioreactor.

Advanced treatment of petrochemical wastewater by combined ozonation and biological aerated filter.

The secondary effluent from a petrochemical wastewater treatment plant was treated by biological aerated filter (BAF) before and after ozonation, namely BAF1 and BAF2, respectively. The results showed that BAF2 fed with the ozonized secondary effluent exhibited a high efficiency in degrading organic pollutants. The removal efficiency of COD and NH4-N was 6.0 ± 3.2 and 48.2~18.6% for BAF1 and 12.5 ± 5.8 and 62.1~40.9% for BAF2, respectively, during the whole operation. The integration system of ozonation and BAF could tolerate a higher organic loading rate. When HRT decreased from 4 to 1h, COD removal efficiency decreased from 12 to 4% for the BAF1 system, but it kept almost unchanged at high levels of 27-32% for the ozonation-BAF2 system, with around 20% removal by ozonation. The biomass in BAF2 exhibited a higher activity of protease, DHA, and SOUR than that in BAF1. The organic pollutants in influent and effluent of BAF were mainly ester compounds, which were difficult to biodegrade by BAF. The predominant genera in BAF1 were Gemmatimonadaceae uncultured, Thauera, and Thiobacillus, while the dominant genera in BAF2 were Nitrospira, Gemmatimonadaceae uncultured, and Flexibacter, respectively. Overall, BAF2 performed better than BAF1 in organic pollutant removal and microbial activity. The ozonation process was vital for BAF to treat petrochemical secondary effluent.

Nutrient removal from synthetic and secondary treated sewage and tannery wastewater through phycoremediation

ABSTRACTIn this study, potential microalgae species (Chlorella vulgaris, Scenedesmus dimorphus, Chlorococcum sp. and Chlamydomonas sp.) have been studied for nutrient removal from synthetic and industrial wastewater. Batch experiments were carried out to investigate the removal performance among four chosen species at different nitrogen and phosphorus concentrations. NH4-N and PO4-P were varied from 13.2 to 52.8 mg/L and 6.6 to 26.4 mg/L, respectively, by keeping N:P ratio as 2:1. In synthetic wastewater, maximum NH4-N and PO4-P removal efficiencies of 88.6% and 91.2% were obtained with C. vulgaris when compared to the other microalgae studied. Further studies were carried out using C. vulgaris in batch experiments to investigate the nutrient removal performance in secondary treated sewage, soak liquor and composite tannery effluent. Experimental results indicated that NH4-N, NO3-N, PO4-P and chemical oxygen demand (COD) removal efficiencies were found to be 68.6%, 74%, 71.5% and 90.2%, respectively, in secondary treated sewage. Maximum removal efficiencies of NH4-N, NO3-N, PO4-P and COD in composite tannery wastewater were found to be 55%, 85.6%, 60.5% and 43.4%, respectively. In soak liquor, maximum removal efficiencies of NH4-N, NO3-N, PO4-P and COD were found to 66.7%, 62.6%, 63.6% and 93.8%, respectively.

Nitrogen removal from sewage and septage in constructed wetland mesocosms using sand media amended with biochar

Biochar has been identified as a media amendment to improve nutrient removal from wastewater, and N retention and plant growth in agroforestry. It therefore has the potential for treating domestic wastewater. The aim of this research was to compare nitrogen removal and plant growth in pure sand and sand amended with biochar, in wetland mesocosms (240L) receiving sewage. There were seven media treatments based on the proportions of biochar in the sand media (100% sand, sand and coir peat, 5, 10, 15, 20, 25% biochar). The plant species were Paperback tree (Melaleuca quinquenervia) and Lemongrass (Cymbopogon citratus). The mesocosms were continuously loaded for 8 months with secondary clarified wastewater (SCW) (16L/day). Septage was then intermittently loaded (20L/2days) for a further 8 months. Inflow and outflow samples were monitored for TN, NH4-N, and NOx-N.All treatments showed good nitrogen removal efficiency. Average removal efficiencies of TN, NOx-N and NH4-N in the mesocosms loaded with SCW ranged from 71 to 87%, 81 to 93% and 65 to 79%, for 100% Sand to 25% Biochar respectively. For septage, the removal efficiencies ranged from 63 to 81%, 69 to 87% and 66 to 81%, for 100% Sand to 25% Biochar respectively. Significant differences of nitrogen outflow concentrations were observed between pure sand and sand amended with biochar. Physical chemical properties of the biochar would have facilitated microbial processes and adsorption. Strong positive correlations were observed between biochar content in the media and nitrogen removal rates. The increased nitrogen removal may be attributed to higher mineralisation of organic nitrogen and NH4-N, especially in the case of septage where strong correlation was observed between BOD5 and TN removal. Total N biomass in the plants harvested after 21 months ranged from 13.4–14.0gN. The addition of biochar did not increase plant N biomass in either species.

Mechanism of high contaminant removal performance in the expanded granular sludge blanket (EGSB) reactor involved with granular activated carbon for low-strength wastewater treatment

The sludge granulation in an anaerobic bioreactor is rather difficult for treating low-strength wastewater. In this study, an expanded granular sludge blanket (EGSB) reactor involved with granular activated carbon (GAC) was employed to treat wastewater at different operational conditions. In general, a stable COD removal performance was operated at the HRT condition of 8, 6, 5, and 4 h, and Vup ranges from 1.09 to 2.44 m h−1. However, the NH3-N removal efficiency was at a relatively low level resulted from the nitrification efficiency was limited to the low dissolved oxygen concentration in anaerobic bioreactor. Adding GAC to the raw sludge, the average size of granular sludge and enzymatic [dehydrogenase activity (DHA) and specific methanogenic activity (SMA)] activities presented an increase trend with the experiment grows. In addition, the promotion of organic load rate (OLR) and Vup might stimulate the external mass transfer effect in EGSB reactor, which resulted in the increase of extracellular polymeric substances (EPS) content. DNA sequencing analysis demonstrated that the growth of Aeromonas genus was the main reason for the unstable distribution of acetoclastic and hydrogenotrophic methanogens in HRT condition of 4 h.

Improving sludge settleability by introducing an innovative, two-stage settling sequencing batch reactor

Sludge settleability is considered one of the main drawbacks of sequencing batch reactors. The aim of this study therefore is to improve sludge settleability by introducing a novel, two-stage settling sequencing batch reactor (TSSBR) separated by an anoxic stage. The performance of the TSSBR was compared with that of a normal operating sequencing batch reactor (NOSBR), operating with the same cycle time. The results show a significant improvement in sludge settleability and nitrogen compound removal rates for the TSSBR over the NOSBR. The average removal efficiencies of NH3-N, NO3-N and NO2-N have been improved from 76.6%, 86.4% and 87.3% respectively for the NOSBR to 89.2%, 95.2% and 96% respectively for the TSSBR. In addition, the average SVI30 for the NOSBR has been reduced from 42.04ml/g to 31.17ml/g for the TSSBR. After three months of operation, there was an overgrowth of filamentous bacteria inside the NOSBR reactor, while the morphological characteristics of the sludge inside the TSSBR reactor indicated a better and homogenous growth of filamentous bacteria.

Removal of selected nitrogenous heterocyclic compounds in biologically pretreated coal gasification wastewater (BPCGW) using the catalytic ozonation process combined with the two-stage membrane bioreactor (MBR)

Three identical anoxic-aerobic membrane bioreactors (MBRs) were operated in parallel for 300 consecutive days for raw (R1), ozonated (R2) and catalytic ozonated (R3) biologically pretreated coal gasification wastewater (BPCGW) treatment. The results demonstrated that catalytic ozonation process (COP) applied asa pretreatment remarkably improved the performance of the unsatisfactory single MBR. The overall removal efficiencies of COD, NH3-N and TN in R3 were 92.7%, 95.6% and 80.6%, respectively. In addition, typical nitrogenous heterocyclic compounds (NHCs) of quinoline, pyridine and indole were completely removed in the integrated process. Moreover, COP could alter sludge properties and reshape microbial community structure, thus delaying the occurrence of membrane fouling. Finally, the total cost for this integrated process was estimated to be lower than that of single MBR. The results of this study suggest that COP is a good option to enhance pollutants removal and alleviate membrane fouling in the MBR for BPCGW treatment.

Bioenergy generation and rhizodegradation as affected by microbial community distribution in a coupled constructed wetland-microbial fuel cell system associated with three macrophytes

Rhizodeposits excreted by various macrophytes might lead to the potential discrepancy of microbial community distribution in constructed wetland coupled with microbial fuel cell (CW-MFC), which has been considered as main factors for the variations of bioelectricity generation during wastewater treatment. In this study, CW-MFC has been associated with three macrophytes (J. effuses, T. orientalis and S. validus) for domestic sewage treatment, also unplanted CW-MFC was performed as a control system. Macrophyte T. orientalis and S. validus can significantly strengthen the bioenergy output in CW-MFC. Highest current (94.27mAm−2) and power densities (21.53mWm−2) were obtained in CW-MFC planted with T. orientalis. Removal efficiencies of COD, NO3-N and NH3-N in CW-MFC planted with S. validus was respectively 5.8%, 7.2%, and 23.9% higher than that of unplanted system. Notably, the oxygen depletion in S. validus CW-MFC reactor during the dark cycle was higher that of other reactors. Results of high-throughput sequencing analysis showed that higher biodiversity was observed in rhizosphere than that of anode material, and the relative abundance of Desulfobulbus sp. and Geobacter sp. has been apparently promoted in the samples of rhizosphere. However, a higher relative abundance of electrochemically active bacteria (Proteobacteria) was observed on the surface of anode electrode material. In addition, microbes (Cytophagales, Clostridium sp., and Dechloromonas sp., and so forth) found in rhizosphere show a capability to decompose refractory contaminants. These contaminants and death roots in the upper part of wetland could be oxidized to fat acids, which may be used as the electrons acceptors for promoting the bioelectricity generation during wastewater treatment.

The investigation of paper mill industry wastewater treatment and activated sludge properties in a submerged membrane bioreactor.

The paper mill industry produces high amounts of wastewater and, for this reason, stringent discharge limits are applied for sustainable reclamation and reuse of paper mill industry wastewater in many countries. Submerged membrane bioreactor (sMBR) systems can create new opportunities to eliminate dissolved substances present in paper mill wastewater including. In this study, a sMBR was operated for the treatment of paper mill industry wastewater at 35 h of hydraulic retention time (HRT) and 40 d of sludge retention time (SRT). The chemical oxygen demand (COD), NH3-N and total phosphorus (TP) removal efficiencies were found to be 98%, 92.99% and 96.36%. The results demonstrated that sMBR was a suitable treatment for the removal of organic matter and nutrients for treating paper mill wastewater except for the problem of calcium accumulation. During the experimental studies, it was noted that the inorganic fraction of the sludge increased as a result of calcium accumulation in the reactor and increased membrane fouling was observed on the membrane surface due to the calcification problem encountered. The properties of the sludge, such as extracellular polymeric substances (EPS) and soluble microbial products (SMP), relative hydrophobicity, zeta potential and floc size distribution were also monitored. According to the obtained results, the total EPS was found to be 43.93 mg/gMLSS and the average total SMP rejection by the membrane was determined as 66.2%.

Investigating nitrogen removal using simultaneous nitrification-denitrification in transferring wastewater through collection networks with small-diameter pipes

This study evaluates the removal of nitrogen compounds from wastewater in modified, small diameter gravity slope (SDGS) pipes during its conveyance. A 13-meter long, closed loop, wastewater collection network was designed and built at laboratory scale. The modified SDGS consists of Polyvinyl Chloride (PVC) tubes with perforated plastic netting fixed to the inner surfaces, to enhance biofilm attachment and growth under gravity flow. The system was operated at constant temperature using synthetic wastewater similar to municipal wastewater. The efficiency of ammoniacal nitrogen (NH3-N) removal at initial chemical oxygen demand (COD) concentrations of 340, 570, and 860 mg/L was studied. The NH3-N batch concentrations tested were 4.58, 6.32, and 9.48 mg/L, respectively. The results showed that nitrogen loss under aerobic conditions may have been due to simultaneous nitrification and denitrification, which began to operate when the biofilm was between 2.5 and 5.5 mm thick. A maximum NH3-N removal efficiency of 75% was achieved following 10 hours' circulation period, at a COD concentration of 570 mg/L.

Potential of integrated vertical and horizontal flow constructed wetland with native plants for sewage treatment under different hydraulic loading rates.

In this study, a pilot-scale integrated constructed wetland with vertical flow (VF) and horizontal flow (HF) in series was designed and investigated to evaluate sewage wastewater treatment capacity. The VF unit was planted with Canna indica and was 1.2 m long, 1.2 m wide, and 1.2 m high; whereas the HF unit contained Colocasia esculenta and was 3.0 m long, 1.0 m wide, and 1.0 m high. The system was operated under different hydraulic loading rates (HLRs) of 0.1, 0.2, and 0.15 m/d. The effluent concentrations differed as HLR changed, and the means were total suspended solids (TSS): 87 mg/L; biological oxygen demand (BOD5): 31 mg/L; chemical oxygen demand (CODCr): 59 mg/L; ammonium nitrogen (NH4-N): 5.3 mg/L; nitrate nitrogen NO3-N: 8.4 mg/L; total nitrogen (TN): 7.1 mg/L; phosphate (PO4-P): 0.9 mg/L; and total coliforms (TCol): 1,485 most probable number (MPN)/100 mL. The average removal efficiencies for TSS, BOD5, TN, NH4-N, PO4-P, and TCol were 28.3, 74.9, 79, 76.2, 3.6, and 82%, respectively. There were significant differences in the effluent concentrations among the three HLRs (P < 0.05), except for PO4-P.

High-load domestic wastewater treatment using a combined anaerobic-aerobic bio-filter with coal cinder as medium

ABSTRACTA combined anaerobic-aerobic bio-filter technology was used for field treatment of high-organic-load domestic wastewater with coal cinder as the bio-filter medium. The effects of parameters, including hydraulic retention time (HRT) and backflow ratio, on the decrease in the chemical oxygen demand (COD), NH3-N, total nitrogen (TN), total phosphorus (TP), and turbidity were investigated. The results showed the obvious influence of the HRT and ratio of backflow on wastewater treatment. Under the optimal HRT condition of 18 h, the removal efficiencies of COD, NH3-N, TN, TP, and turbidity were 67.9%, 95.6%, 30.4%, 65.6%, and 83.8%, respectively. When the backflow ratio (2:1) was added to the treatment system, the TN removal obviously increased, and the removal efficiencies of COD, NH3-N, TN, TP, and turbidity were 88.1%, 91.7%, 69.9%, 69.6%, and 97.5%, respectively. These results indicated that the combined technology has the potential as a treatment method for high-organic-load domestic wastewater.

Construction of Microbial Consortium and Its Directly Treatment for the Black-odor Water

Recently, how to efficiently treat the black-odor water in China has become an urgent issue. In this study, a microbial consortium which consisted of yeast, actinomyce and nitrobacteria isolated from East Sha River located in Beijing was constructed and used to directly treat black-odor water, and the removal efficiency was also investigated. The experimental results showed that the microbial consortium exhibited more significant removal efficiency in comparison with single strains. The mixing proportion of single strains in the microbial consortium was then optimized. It was found that a high removal level of COD, NH3-N and TP could be achieved when the mixing proportion of yeast, actinomyce and mitrobactera was set at 1:1:1, and their removal efficiencies arrived at 60.2%, 81.7% and 85.7%, respectively. Furthermore, the optimizing microbial consortium was applied to treat other some black-odor water from Qing River, Qinghe Park and a pharmaceutical manufactory, respectively. With the exception of water sample from the pharmaceutical manufactory, the optimizing microbial consortium showed obvious potentials to treat the black-odor water, especially the water from urban rivers. Removal efficiencies of NH3-N, TP and chroma in the water sample from Qing River were above 95%.

Ammonia nitrogen removal and recovery from acetylene purification wastewater by air stripping.

Ammonia nitrogen (NH4-N) contaminated wastewater has posed a great threat to the safety of water resources. In this study, air stripping was employed to remove and recover NH4-N from acetylene purification wastewater (APW) in a polyvinylchloride manufacturing plant. Investigated parameters were initial APW pH, air flow rate, APW temperature and stripping time. The NH4-N removal by air stripping has been modeled and the overall volumetric mass transfer coefficient (KLa) of the stripping process has been calculated from the model equation obtained. In addition, the ability of H2SO4 solution to absorb the NH3 stripped was also investigated. The results indicated that under the experimental conditions, the APW temperature and its initial pH had significant effects on the NH4-N removal efficiency and the KLa, while the effects of other factors were relatively minor. The removal efficiency and residual concentration of NH4-N were about 91% and 12 mg/L, respectively, at the optimal operating conditions of initial APW pH of 12.0, air flow rate of 0.500 m3/(h·L), APW temperature of 60 °C and stripping time of 120 min. One volume of H2SO4 solution (0.2 mol/L) could absorb about 93% of the NH3 stripped from 54 volumes of the APW.

Denitrification of aging biogas slurry from livestock farm by photosynthetic bacteria

Huge amount of aging biogas slurry is in urgent need to be treated properly. However, due to high NH3-N concentration and low C/N ratio, this aging biogas slurry is refractory for traditional methods. Its denitrification has become a big challenge. In this paper, photosynthetic bacteria (PSB) were employed to handle this problem. The results showed denitrification of aging biogas slurry by PSB treatment was promising. The highest removal efficiency of NH3-N reached 99.75%, much higher than all other treatments. The removal of NH3-N followed pseudo zero order reaction under dark-aerobic condition. The better inoculation rate for NH3-N removal was 30%; and aerobic condition was more beneficial for NH3-N removal than anaerobic condition because of different metabolic pathways.

PRE-TREATMENT AMMONIA REMOVAL OF SCHEDULED WASTE LEACHATE WITH HYDRATED LIME AND CAUSTIC SODA

Leachate is known to be hazardous wastewater in terms of its organic matter and ammonia content. Various methods have been studied extensively for the treatment of different types of leachate. However, scheduled waste leachate is rarely studied due to its complex characteristics and highly contaminated nature compared to other types of landfill leachates. In this study, hydrated lime (Ca(OH)2) and caustic soda (NaOH) as softener agent were used for increasing the pH of the treatment process of scheduled waste leachate to remove ammonia-nitrogen (NH3-N). Chemical oxygen demand (COD) and colour removal were also evaluated. Jar test experiments was performed using Ca(OH)2 and NaOH at varying dosages ranging from nil to 12 g L-1. A Historical Data Design (HDD) of Response Surface Methodology (RSM) was employed to optimize the parameters affecting NH3-N, COD and colour removal efficiency. The optimal conditions obtained from desirable response were predicted at 5.9 g L-1 of Ca(OH)2 dosage, where the maximum NH3-N, COD and colour removal efficiency would be 49%, 18% and 66%, respectively. Meanwhile for NaOH, dosage of 6.4 g L-1 waspredicted to remove NH3-N, COD and colour up to 32%, 4% and 42%, respectively. The predicted values concurred with the experiments, in which Ca(OH)2 successfully reducing NH3‑N, COD and colour up to 52 %, 17.5 % and 65 %, while NaOH could only remove NH3-N, COD and colour by up to 35 %, 2 % and 49 %, respectively. The results obtained from this study suggest that hydrated lime (Ca(OH)2), is more feasible to be used for the pre-treatment process of scheduled waste leachate as less dosage is required with higher removal efficiencies of NH3-N, COD and colour. This study demonstrates that RSM was a reliable tool to predict the optimum dosage and suitable types of chemicals for the removal of NH3-N, COD and colour from the available data.

A novel design for a compact constructed wetland introducing multi-filtration layers coupled with subsurface superficial space

A novel design for a compact constructed wetland with a multi-layer structure is proposed in this study. A four-layer vertical flow constructed wetland (VFCW) in which four filtration layers were coupled with three subsurface superficial spaces (SSS) was designed, so that the land needed for a VFCW can decrease to one-fourth as large as a conventional single-layer VFCW. The treatment performance of the proposed multi-layer constructed wetland (MLCW) was tested by treating anaerobic digestates containing CODCr and nutrients in high concentrations. The removal efficiencies for CODCr, total phosphorus (TP) and NH4-N were >99%, >96% and >99%, respectively, and a high nominal oxygen transfer rate (OTR) of 102gO2/m2d was attained. This indicated successful aerobic treatment despite a much smaller land area being used compared with that required for a single-layer VFCW. To enhance denitrification, the treatment performance of MLCW was also tested under partially saturated conditions, when the third and fourth filtration layers were saturated with water. The removal efficiency for total nitrogen (TN) improved to 76.5%, while that for CODCr, TP and NH4-N was comparable to that obtained in unsaturated conditions. This result indicated that MLCW with partially saturated layers may provide an alternative hybrid system enhancing both aerobic and anaerobic treatment, although further research to improve anaerobic reactions is required. Nevertheless, the potential of MLCW as a novel approach to reduce the land area needed for constructed wetlands (CWs) was clearly demonstrated.

Enhancement of surface flow constructed wetlands performance at low temperature through seasonal plant collocation

In the present study, a novel seasonal plant collocation system (SPCS), specifically the Potamogeton crispus and Phragmites australis series system, was investigated to enhance the performance of surface flow constructed wetlands (SFCWs) at low temperature. Results of a year-round experiment showed that SPCS conquered the adverse effect of low temperature and achieved sustainable nutrients removal. In addition, during winter, removal efficiencies of NH4-N, TP, COD, and TN in SPCS were 18.1%, 17.6%, 10.1% and 5.2% higher than that in the control, respectively. P. crispus and P. australis complemented each other in terms of plant growth and plant uptake during the experiment period. Furthermore, it emerged that P. crispus could increase the quantity of ammonia oxidizing bacteria by 10.2%, due to its high oxygen enrichment ability. It is suggested that seasonal plant collocation has a promising future in SFCWs of areas being affected by climate change, e.g. northern China.

Performance of integrated anaerobic/aerobic sequencing batch reactor treating poultry slaughterhouse wastewater

The present study investigates the performance of a new configuration laboratory-scale bioreactor comprising of two regimes (anaerobic & aerobic) in one reactor with physical separation and it is known as integrated anaerobic/aerobic sequencing batch reactor (IAASBR). The IAASBR is designed for treating high-strength wastewater such as poultry slaughterhouse wastewater (PSW) along with the simultaneous removal of organic carbon and ammoniacal nitrogen (NH3-N). The IAASBR exhibits that the average removal efficiency of total COD (TCOD), soluble COD (SCOD), NH3-N, fat, oil & grease (FOG), and total suspended solids (TSS) were (97%±2%), (95%±3%), (98%±1.3%), (90%±11%), and (96%±3%) respectively. The laboratory comparison test revealed that IAASBR configuration has enhanced the sludge settle-ability for aerobic SBR more than the conventional SBR or settling tank. Furthermore, IAASBR could tolerate the shock loading occurrence, handle organic loading rate (OLR) up to 4.5kg(TCOD)m−3d−1 and produce a high-quality effluent complying with Malaysian standards of industrial’s effluents.

Effect of bioflocculation on fouling-related biofoulants in a membrane bioreactor during saline wastewater treatments

A membrane bioreactor (MBR) was operated in two modes; with and without the inoculation of marine Arthrobacter cells, to investigate the effect of bioflocculation on membrane biofouling during saline wastewater treatments. The MBR-Arthrobacter system showed a higher resistance to membrane fouling than the normal MBR system. Lower concentrations of the fouling-related components and higher removal efficiencies of COD and NH3-N were observed in the MBR-Arthrobacter system. The bioflocculation of Arthrobacter preferred to settle down the humic acid-like, fulvic acid-like and aromatic proteins components (larger biomolecules) rather than the soluble microbial by-product-like components (smaller biomolecules).