Synthetic Sewage Research Articles

Low-cost, reliable, and highly efficient removal of COD and total nitrogen from sewage using a sponge-filled trickling filter.

Development of low-cost and reliable reactors demanding minimal supervision is a need-of-the-hour for sewage treatment in rural areas. This study explores the performance of a multi-stage sponge-filled trickling filter (SPTF) for sewage treatment, employing polyethylene (PE) and polyurethane (PU) media. Chemical oxygen demand (COD) and nitrogen transformation were evaluated at hydraulic loading rates (HLRs) ranging from 2 to 6 m/d using synthetic sewage as influent. At influent COD of ∼350 mg/L, PU-SPTF and PE-SPTF achieved a COD removal of 97% across all HLRs with most of the removal occurring in the first segments. Operation of PE-SPTF at an HLR of 6 m/d caused substantial wash-out of biomass, while PU-SPTF retained biomass and achieved effluent COD < 10 mg/L even at HLR of 8-10 m/d. The maximum Total Nitrogen removal by PE-SPTF and PU-SPTF reactors was 93.56 ± 1.36 and 92.24 ± 0.66%, respectively, at an HLR of 6 m/d. Simultaneous removal of ammonia and nitrate was observed at all the HLRs in the first segment of both SPTFs indicating ANAMMOX activity. COD removal data, media depth, and HLRs were fitted (R2 > 0.99) to a first-order kinetic relationship. For a comparable COD removal, CO2 emission by PU-SPTF was 3.5% of that of an activated sludge system.

Achieving Long-Term Stability of Partial Nitrification and Autotrophic Denitrification in an MABR via Sulfide Dosing.

While partial nitrification (PN) has the potential to reduce energy for aeration, it has proven to be unstable when treating low-strength wastewater. This study introduces an innovative combined strategy incorporating a low rate of oxygen supply, pH control, and sulfide addition to selectively inhibit nitrite-oxidizing bacteria (NOB). This strategy led to a stable PN in a laboratory-scale membrane aerated biofilm reactor (MABR). Over a period of 260 days, the nitrite accumulation ratio exceeded 60% when treating synthetic sewage containing 50 mg NH4+-N/L. Through in situ activity testing and high-throughput sequencing, the combined strategy led to low levels of nitrite-oxidation activity (<5.5 mg N/m2 h), Nitrospira species (relative abundance <1%), and transcription of nitrite-oxidation genes (undetectable). The addition of sulfide led to simultaneous PN and autotrophic denitrification in the single-stage MABR, resulting in over 60% total inorganic nitrogen removal. Sulfur-based autotrophic denitrification consumed nitrite and inhibited NOB conversion of nitrite to nitrate. The combined strategy has potential to be applied in large-scale sewage treatment and deserves further exploration.

Impacts on Soil and Cowpea Plants Fertigated with Sanitary Sewage through Subsurface Drip Irrigation

The application of sanitary sewage using subsurface drip irrigation can mitigate current challenges related to water availability and food production. However, before implementing these techniques, it is crucial to conduct studies to assess their impacts on soil and plants. The objective of this study was to evaluate chemical changes in the soil and the development of cowpeas subjected to sanitary sewage applied by drippers with different flow rates and installation depths. Drippers were positioned at various depths (0 to 30 cm) and operated with flow rates of 1.6 and 3.8 L h−1. Cowpeas were cultivated in pots with clayey soil, using synthetic sanitary sewage based on the maximum limit of nitrogen fertilization. Irrigation management was controlled in terms of soil moisture, which was monitored using TDR probes. The results indicated that reducing the depth of the drippers positively affected grain production and the development of cowpeas. Fertigation with sanitary sewage at greater depths increased soil phosphorus concentrations and base saturation. Dripper depth also influenced soil concentrations of phosphorus, potassium, calcium, and magnesium, while sodium concentrations decreased with greater depth. It is concluded that dripper flow rates did not impact soil chemical parameters or the agronomic characteristics of cowpeas. However, despite nutrient supply at greater depths, the subsurface drip irrigation system proved unsuitable for cowpea production in clayey soil.

Effect of zeolites on the reduction of the ecotoxicity of carbamazepine in the environment

In this study, the impact of calcination of zeolites on the ecotoxicity of carbamazepine solutions in two matrices, water and synthetic sewage, was assessed. Two types of zeolites were tested: natural zeolite, in the form of a zeolite rock consisting mainly of clinoptilolite, and a synthetic zeolite type 5 A. Additionally, zeolites were calcined at a temperature of 200 °C. The kinetics of carbamazepine adsorption in aqueous solutions and in synthetic sewage matrix was determined. Higher adsorption capacity was obtained for carbamazepine aqueous solutions as well as zeolites after the calcination process. Considering type of zeolite, the highest and fastest uptake of carbamazepine was observed for natural zeolite after calcination. In the case of ecotoxicity, carbamazepine solutions before adsorption was the most toxic towards Raphidocelis subcapitata, next Aliivibrio fischeri and Daphnia magna, regardless to the matrix type. The differentiation in toxicity regarding the type of matrix was observed, in the case of algae and bacteria, higher toxicity was demonstrated by carbamazepine solutions in the water matrix, while in the case of crustaceans—the sewage matrix. After the adsorption process, the toxicity of carbamazepine solutions on zeolites decreased by 34.5–60.9 % for R. subcapitata, 33–39 % for A. fischeri and 55–60 % for D. magna, thus confirming the effectiveness of the proposed method of carbamazepine immobilization.

Adsorption of ammonium ion (NH4+) using mordenite-chitosan from synthetic and actual sewage: Batch and fixed-bed studies

The untapped NH4+ in sewage has the potential to be recovered as fertilizer via the adsorption process. While zeolite-chitosan has demonstrated better performance in nutrient recovery compared to powder zeolite, research on mordenite-chitosan remains limited. Therefore, this study focused on the mordenite-chitosan for NH4+ recovery. Based on the characterization, the physicochemical properties of mordenite-chitosan closely resemble the mordenite. The addition of chitosan has increased the adsorption capacity of mordenite by 15%. The adsorption of NH4+ on mordenite-chitosan fitted well to the Langmuir linear model with an estimated adsorption capacity of 17.7 mg/g (R2 = 0.991). The positive entropy with an enthalpy value of 44.47 kJ/mol suggests a random organization of NH4+ ions, endothermic process, and ion-exchange. Mordenite-chitosan adhered well to the Thomas model, with NH4+ adsorption capacity of 17.97 mg/g, 6.14 mg/g, and 4.84 mg/g in synthetic sewage, influent, and effluent, respectively. Factors such as the negativity of the surface mordenite-chitosan, Si/Al ratio, and framework flexibility are likely to influence the NH4+ adsorption capacity. Overall, the ion-exchange property of mordenite-chitosan emerges as the main contributor to its efficacy in NH4+ recovery.

Microplastics Prevalence in Different Cetaceans Stranded along the Western Taiwan Strait.

Microplastics (MPs) pollution is of global concern, which poses serious threats to various marine organisms, including many threatened apex predators. In this study, MPs were investigated from nine cetaceans of four different species, comprising one common dolphin (Delphinus delphis), two pygmy sperm whales (Kogia breviceps), one ginkgo-toothed beaked whale (Mesoplodon ginkgodens), and five Indo-Pacific humpback dolphins (Sousa chinensis) stranded along the western coast of the Taiwan Strait from the East China Sea based on Fourier transform infrared (FTIR) spectroscopy analysis. Mean abundances of 778 identified MPs items were 86.44 ± 12.22 items individual-1 and 0.43 ± 0.19 items g-1 wet weight of intestine contents, which were found predominantly to be transparent, fiber-shaped polyethylene terephthalate (PET) items usually between 0.5 and 5 mm. The abundance of MPs was found at a slightly higher level and significantly correlated with intestine contents mass (p = 0.0004*). The MPs source was mainly likely from synthetic fibers-laden sewage discharged from intense textile industries. Our report represents the first study of MPs in pelagic and deep-diving cetaceans in China, which not only adds baseline data on MPs for cetaceans in Asian waters but also highlights the further risk assessment of MPs consumption in these threatened species.

Impact of mixed microalgal and bacterial species on organic micropollutants removal in photobioreactors under natural light

Single microalgae species are effective at the removal of various organic micropollutants (OMPs), however increased species diversity might enhance this removal. Sixteen OMPs were added to 2 continuous photobioreactors, one inoculated with Chlorella sorokiniana and the other with a microalgal-bacterial community, for 112 d under natural light. Three media were sequentially used in 3 Periods: I) synthetic sewage (d 0–28), II) 10x diluted anaerobically digested black water (AnBW) (d 28–94) and III) 5x diluted AnBW (d 94–112). Twelve OMPs were removed > 30 %, while 4 were < 10 % removed. Removal efficiencies were similar for 9 OMPs, yet the mixed community showed a 2–3 times higher removal capacity (µg OMP/g dry weight) than C. sorokiniana during Period II pseudo steady state. The removal decreased drastically in Period III due to overgrowth of filamentous green algae. This study shows for the first time how microbial community composition and abundance are key for OMPs removal.

Shiitake spent mushroom substrate as a sustainable feedstock for developing highly efficient nitrogen-doped biochars for treatment of dye-contaminated water

Edible white-rot mushrooms are organisms that are cultivated at an industrial scale using wood-based substrates. The mushroom industry has an estimated annual production of 34 Mt of edible mushrooms, and approximately 70 wt% of the substrate is left as waste known as spent mushroom substrate (SMS). The huge volumes of SMS generated by mushroom farms hinder proper recycling, meaning that combustion or open-field burning are common disposal practices. This paper shows a concept that could help reduce the environmental impact of the mushroom industry. SMS from the cultivation of shiitake mushroom was used as a carbon precursor for the production of nitrogen-doped activated biochar that was used to remove reactive orange-16 (RO-16) azo dye from water, as well as contaminants from two synthetic effluents and real sewage water. Melamine was used as a nitrogen dopant and phosphoric acid as an activating agent. Samples without the addition of melamine were used for comparison. The doping/impregnation process was carried out in one-step, followed by pyrolysis at 700 and 900 °C for 1 h. BET, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used for the characterization of the biochars. The specific surface area of the doped samples was slightly lower, i.e., 1011 m2/g (SMS-700 °C), 810 m2/g (SMS-700 °C + N), 1095 m2/g (SMS-900 °C), and 943 m2/g (SMS-900 °C + N). Raman spectroscopic analysis showed that the N-doped biochars had more defective carbon structures than the non-doped ones. XPS analysis showed that doping with melamine led to the formation of N-functionalities on the surface of the biochar particles. The kinetics of adsorption were well represented by the Avrami model. The adsorption isotherms were well-fitted by the Liu model. The maximum adsorption capacities (qmax) of RO-16 were much higher for the N-doped biochars, i.e., 120 mg/g (SMS-700 °C), 216 mg/g (SMS-700 °C + N), 168 mg/g (SMS-900 °C), and 393 mg/g (SMS-900 °C + N). N-doped biochar samples were more effective for the removal of contaminants from synthetic effluents and sewage water. N-doped biochar produced at 900 °C showed good recyclability. This work concludes that SMS is a valuable waste that could be used for the production of activated carbon and that N-doping helped to improve the adsorption performance to a great extent.

Coagulation performance and floc characteristics of Fe–Ti–V ternary inorganic coagulant for organic wastewater treatment

A novel Fe–Ti–V ternary inorganic coagulant (VTMS) was prepared from vanadium titanomagnetite (VTM) by two-step sulfuric acid leaching method, which is simple, efficient, and economical. VTMS was used to treat four typical organic wastewaters: synthetic domestic sewage, oily wastewater, surface water, and algae-laden water. The results indicated that it was superior to conventional coagulants. VTMS achieved a turbidity removal rate of nearly 100 % for all four wastewaters. In addition, it performed better in organic matter removal than polyaluminum chloride (PAC) with a larger floc size and higher growth rate. These results were attributed to the hydrolysis of Fe, Ti, and V, which formed a chain structure that improved the adsorption, bridging, and sweeping performances of VTMS. Based on the observations of coagulation performance, floc properties, and zeta potential, the predominant coagulation mechanisms appeared to be charge neutralization in synthetic domestic sewage and bridging flocculation in oily wastewater, surface water, and algae-laden water. Sweep coagulation also played a role in the coagulation processes for all four wastewaters. This study provided efficient technical guidance for large-scale production and application of Ti-based coagulants.

Effectiveness of Opuntia ficus indica (cactus) fruit juice for sludge conditioning.

The possibility of using Opuntia ficus indica fruit juice (OFIFJ) as a bioflocculant for conditioning the synthetic kaolin sludge and sewage sludge (region Oran, Algeria, and Pau, France) was studied. Turbidity of the supernatant, dryness of the sludge cake, and total time of filtration (TTF) were examined parameters. Using vacuum filtration, lime was also tested as a chemical conditioner and gives good results on Lescar (France) sewage sludge in terms of cake's dryness, filtrate quality, turbidity (13.54%), and total time of filtration (TTF = 85.29%), comparing to the industrial polymer (Sedifloc 408C; turbidity; 8.33% and TTF: 2.94%). For the sewage sludge of Oran (Algeria), the results obtained with OFIFJ were compared to those obtained with the cladodes juice of the same plant OFIC, and also with a cationic polymer (Superfloc 8396). For an optimum dosage, it showed that OFIFJ has a flocculation activity as same as the cladodes juice OFIC for sludge conditioning and gives better results in terms of turbidity (dosage of 22.4g/kg DM: 3.7 NTU for OFIC, dosage of 8.36: 3.63 NTU for OFIFJ. Dryness was enhanced from 14.91 to 22.93% (OFIC 16g/kg DM) and to 24.48% (OFIF 20.9g/kg DM) but for TTF, we found the opposite. In fact, this plant showed to be an available, biodegradable, and non-toxic flocculant. For kaolin synthetic sludge (30%), the optimum dosages of those conditioners were found to be 0.066gkg-1 for OFIC, comparing between vacuum filtration and filtration compression; turbidity was enhanced for both techniques, contrary to dryness. Concerning the Oran city sewage sludge, both turbidity and dryness were optimized. Same thing for the France sewage sludge, all the studied parameters were enhanced with the two studied bioflocculants.

Unravelling the Biohydrogen Production Potential from a Co-Digestion Process of Banana Processing Wastewater and Synthetic Sewage by Anaerobic Fermentation: Performance Evaluation and Microbial Community Analysis

Unravelling the Biohydrogen Production Potential from a Co-Digestion Process of Banana Processing Wastewater and Synthetic Sewage by Anaerobic Fermentation: Performance Evaluation and Microbial Community Analysis

Spatio-temporal analysis of the sources and transformations of anthropogenic nitrogen in a highly degraded coastal basin in Southeast China.

Nitrogen transport from terrestrial to aquatic environments could cause water quality deterioration and eutrophication. By sampling in the high- and low-flow periods in a highly disturbed coastal basin of Southeast China, hydrochemical characteristics, nitrate stable isotope composition, estimation of potential nitrogen source input fluxes, and the Bayesian mixing model were combined to determine the sources and transformation of nitrogen. Nitrate was the main form of nitrogen. Nitrification, nitrate assimilation, and NH4+ volatilization were the main nitrogen transformation processes, whereas denitrification was limited due to the high flow rate and unsuitable physicochemical properties. For both sampling periods, non-point source pollution from the upper to the middle reaches was the main source of nitrogen, especially in the high-flow period. In addition to synthetic fertilizer, atmospheric deposition and sewage and manure input were also major nitrate sources in the low-flow period. Hydrological condition was the main factor determining nitrate transformation in this coastal basin, despite the high degree of urbanization and the high volume of sewage discharge in the middle to the lower reaches. The findings of this study highlight that the control of agricultural non-point contamination sources is essential to pollution and eutrophication alleviation, especially for watersheds that receive high amounts of annual precipitation.

Evaluation of leachate impact on domestic sewage co-treatment in aerobic granular sludge systems

Aerobic granular sludge (AGS) technology has been consolidated for sewage treatment. However, studies about the co-treatment of landfill leachate in municipal wastewater treatment plants (MWWTPs) with AGS systems are still incipient. The engineering and microbiological aspects of leachate co-treatment with sewage in step-feeding (R1) and conventional (R2) AGS systems were evaluated. Initially, synthetic sewage with a gradual increase in the organic load for granule formation was used (Periods I and II). Subsequently, co-treatment with leachate pre-treated by coagulation-flocculation was carried out with 5% (Period III) and 10% (Period IV) concentrations. Finally, methanol supplementation was conducted as an attempt to improve nutrients removal performance (Period V). Based on the results obtained, the co-treatment in granular reactors was feasible. The best conditions were obtained in R1 during Period V with methanol supplementation. Step-feeding produced a more compact and resistant aerobic granular biomass, resulting in better operational stability. Moreover, this strategy favored denitrification, especially during methanol supplementation, minimizing one of the main problems reported regarding leachate co-treatment in AGS systems. As a result, higher total nitrogen (TN) removals were obtained. At the end of the last period, in R1, Chemical Oxygen Dissolved (COD), TN, and Dissolved Organic Carbon (DOC) removals were 93%, and phosphorus removal was 54%, reaching values higher or similar to other AGS investigations with sewage, leachate, or co-treatment. Therefore, the strategies investigated unprecedentedly contribute to consolidating the domestic sewage co-treatment with leachate in AGS systems and providing a good perspective for other industrial wastewaters.

Hydrogen Production by Aqueous Phase Reforming of Synthetic Sewage Using Pt/C Catalyst: Effect of Reaction Parameters and Pre-Treatment Strategies

Hydrogen Production by Aqueous Phase Reforming of Synthetic Sewage Using Pt/C Catalyst: Effect of Reaction Parameters and Pre-Treatment Strategies

Study of the hydraulic correlation in the removal of pollutants from synthetic wastewater by means of a filter with Musa Paradisiaca

Background: The objective of this work was to decontaminate synthetic sewage from fouracid blue (BRL) dye, with characteristics similar to those of the textile industry, to determine the correlation between flow rate, permeability and removal of hexavalent chromium (Cr+ 6), Cupper (Cu), chemical oxygen demand COD and color using Paradise Muse filter bed. Methods: three concentrations of BRL synthetic wastewater were prepared, determining the initial concentrations of Color, pH, COD, Cr +6 and Cu. In addition, the hydraulic characteristics of the fiber were determined in four types of fiber cut. The synthetic wastewater was filtered in a filtration cell with the three fiber cuts, using three speeds, the time used for these tests was 180 minutes. Water samples were collected every 5 minutes and then analyzed in the laboratory. Simple exponential smoothing was performed on the data obtained, and the statistical analysis of variance ANOVA of 2 factors. Results: The results show that flow velocity and permeability are correlated with color removal, COD and Cr+ 6, determining that the best treatment was to use 1 cm fiber and high flow velocity in which 77.92% and 70.01% for color and COD respectively. In contrast, for Cr+ 6 the best treatment was fiber at 1 cm and low flow velocity removing up to 80% of the concentration of this contaminant and for Cu the best treatment was fiber at 3 cm and low flow velocity removing up to 88.69%. Conclusions: It was determined that the Musa Pardisiaca fiber is capable of absorbing contaminants, but the effectiveness of the treatment depends on the initial conditions of the synthetic water, the cut of the fiber and the velocity. In addition, it is important to mention that, in order to lower heavy metal concentrations, low flow rates should be used.

Long-Term Performance of Nitrogen Removal and Microbial Analysis in an Anammox MBBR Reactor with Internal Circulation to Provide Low Concentration DO.

The anammox process is considered as a revolutionary new denitrification technology. In this study, the anammox process was started in a single-stage moving bed biofilm reactor (MBBR) and the mechanism of excess removal of ammonia nitrogen was studied. At stage I (day 0-51), anammox bacteria (AnAOB) was enriched by feeding synthetic sewage without adding organic carbon. The removal rate of ammonia nitrogen was maintained at about 54% and the removal rate of total inorganic nitrogen was maintained at about 62%. At stage II (day 52-91), internal circulation was added into the MBBR. After adding internal circulation, the ammonium removal efficiency reached about 96% (at day 56) and the total nitrogen removal efficiency reached about 86%. At day 90, the biofilm sample was drowned out for high-throughput sequencing. The results showed that the relative abundance of AnAOB was 23.23%. The dominant anammox genus was Candidatus Brocadia. The relative abundance of Nitrosomonas (ammonia oxidizing bacteria, AOB) was 0.63%. The excess ammonia nitrogen was removed by AOB and AnAOB through the partial nitrification and anammox (PNA) process.

Reuse of expired dairy products and sewage in the production of biogas by anaerobic digestion

Dairy industry is a prominent sector of the agro-industry with global production of 906 million tonnes of milk. Several dairy products are wasted due their high perishability. Anaerobic digestion is a sustainable alternative for reducing this waste aiming biogas production. This study evaluated the co-digestion of expired dairy products (EDP) with synthetic sewage from two assays using two types of dairy waste, separately: Assay I (EDP mixture of 80% of milk + 15% of yogurt + 5% of milk cream) and Assay II (industrial raw mixture of EDP). Both assays were composed of 20 g COD L-1 (Chemical Oxygen Demand per Liter) using anaerobic batch reactors (1.0 L) assembled in duplicates with 0.5 L headspace (N2) and working volume of 0.5 L with initial pH 8.2, at 37 °C, in a static mode. The cumulative CH4 productions were 2722.5 NmL in 31 days of operation (Assay I) and 3140.0 NmL in 25 days of operation (Assay II). Equivalent CH4 yields were obtained for the both assays with ~330 NmLCH4 g CODrem-1. Carbohydrates and COD removals were 96.8% and 98.0%; 87.3% and 89.4%, respectively. The co-digestion of EDP with sewage was effective to CH4 production with efficient organic matter removal. These results encourage new strategies for reuse of expired dairy products by the use of anaerobic digestion.

Determination of cytotoxicity following oxidative treatment of pharmaceutical residues in wastewater

Pharmaceutical residues are released in the aquatic environment due to incomplete removal from wastewater. With the presence of multiple chemicals in sewage waters, contaminants may adversely affect the effectiveness of a wastewater treatment plant (WWTP). In certain cases, discharged metabolites are transformed back into their pristine structure and become bioactive again. Other compounds are persistent and can withstand conventional wastewater treatment. When WWTP effluents are released in surface waters, pristine and persistent chemicals can affect the aquatic environment. To complement WWTPs and circumvent incomplete removal of unwanted chemicals or pharmaceuticals, on-site wastewater treatment can contribute to their removal. Advanced oxidation processes (AOPs) are very powerful techniques for the abatement of pharmaceuticals, however, under certain circumstances reactive toxic by-products can be produced. We studied the application of on-site AOPs in a laboratory setting. It is expected that treatment at the contamination source can eliminate the worst polluters. Thermal plasma and UV/H2O2 oxidation were applied on simulation matrices, Milli-Q and synthetic sewage water spiked with 10 different pharmaceuticals in a range of 0.1 up to 2400μg/L. In addition, untreated end-of-pipe hospital effluent was also subjected to oxidative treatment. The matrices were activated for 180min and added to cultured HeLa cells. The cells were 24h and 48h exposed at 37°C and subsequently markers for oxidative stress and viability were measured. During the UV/H2O2 treatment periods no toxicity was observed. After thermal plasma activation of Milli-Q water (150 and 180min) toxicity was observed. Direct application of thermal plasma treatment in hospital sewage water caused elimination of toxic substances. The low cytotoxicity of treated pharmaceutical residues is likely to become negligible if plasma pre-treated on-site wastewater is further diluted with other sewage water streams, before reaching the WWTP. Our study suggests that AOPs may be promising technologies to remove a substantial portion of pharmaceutical components by degradation at the source. Further studies will have to be performed to verify the feasibility of upscaling this technology from the benchtop to practice.

Development of a low-cost electrochemical sensor for monitoring components in wastewater treatment processes

ABSTRACT Anaerobic digestion (AD) is a complex biological process widely used to decompose various types of organic matter, as well as to produce some metabolites and biogas. Diverse microorganism groups cooperate in many intricate metabolic routes so that organic matter can be degraded. However, any imbalance on these routes can lead to process instability or even failure. Therefore, a proper monitoring system, as well as a good understanding of the process, are key steps to improve performance and stability. Several mathematical models have been developed to represent AD. Despite this, process monitoring is mostly conducted by analytical methods, whose equipment is either expensive or the analyses are time-consuming, which may be a hindrance to low-budget developments. The objective of this study was to develop a low-cost electrochemical sensor to monitor components in wastewater treatment plants. Hundreds of synthetically supplemented sugarcane vinasse and synthetic domestic sewage samples were characterised. The obtained signals were used to calibrate principal component regression, partial least square and artificial neural network estimation models. The predictable variables were chemical oxygen demand, volatile fatty acids, sodium bicarbonate, beef extract, and lipids, and their R2 ranged from 0.84 to 0.99, depending on the component.

Enhanced denitrification of sewage via bio-microcapsules embedding heterotrophic nitrification-aerobic denitrification bacteria Acinetobacter pittii SY9 and corn cob

In this work, bio-microcapsules were prepared by embedding heterotrophic nitrification and aerobic denitrification (HN-AD) bacteria (Acinetobacter Pittii SY9) and corn cob. Bio-microcapsules (20 g/L of corn cob and 30% v/v suspension of strain SY9) were porous (pore size 2579.74–3725.44 nm; porosity 53.6%–79.9%). Under the appropriate conditions (C/N > 2, temperature of 20–35 ℃, rotation speed of 100–120 rpm, pH of 7–9), TN removal efficiency of bio-microcapsules reached 94.4%, and 74.0% of nitrogen was converted into N2. The results of kinetics fitting indicated that aerobic denitrification was the limiting step during HN-AD process. Bio-microcapsules could slow the carbon release of corn cob for 120 days, which ensuring high HN-AD performance even at low C/N of 2.8. Bio-microcapsule SBR could stably run for 88 days with TN removal efficiency > 90% for synthetic sewage. Bio-microcapsules embedding strain SY9 and corn cob have prospective applications for enhancing denitrification of sewage.