Bed Denitrification Research Articles

Application of Deep-bed Denitrification Filter in Sewage Treatment

The combined process of A2/O oxidation ditch, high efficiency sedimentation tank and denitrification deep bed filter was adopted in Sewage Treatment Plant of Hefei City to treat municipal domestic sewage. The effluent quality could meet the discharge limit of major water pollutants in urban sewage treatment plants and industrial industries of Chaohu Lake Basin (DB34/2710-2016). In addition to the parameters of design and operation, the effect of SS and deep denitrification was summarized in detail in this paper. The results showed that the combined process SS and denitrification effect was removed very well. The operational results demonstrated SS removal efficiency 74.3%,TN removal efficiency (92.3％) in the biosystem ,in which 80.0％ and 12.3％ of TN in influent were removed in the pre-denitrif ication in oxidation ditch and post-denitrification in deep bed denitrification filter, respectively. The deep bed denitrification filter could be used as the safeguard for effluent TN with the addition of external carbon source to ensure the efficiency of TN less than 5 mg/L.

Study of nitrogen removal efficiency of the filled bed reactors using alkali-treated corncobs-sulfur (mixotrophic) for treating the effluent from simulated urban wastewater plants

China's urban wastewater treatment plants' nitrogen discharge standards have become more stringent in recent years.In this experiment, the filled bed denitrification system with corncob-sulfur as fillers were constructed for the secondary effluent of the wastewater. The optimum operating conditions of the denitrification reactor with different fillers as electron donors were investigated by varying the operating parameters.According to the experiment, the alkali pretreated corncobs could maintain long-term denitrification effect. The optimum HRT for the mixotrophic denitrification reactor with alkali-treated corncob-sulfur as filler was 1.5 h, with a minimum effluent NO3–-N concentration of 0.31 mg/L and a removal rate of 98.62%, and effluent nitrite nitrogen, NH4+-N, and sulfate accumulation of 0.03 mg/L, 0.71 mg/L and 72.4 mg/L. The reactor with mixed nutrient type had the most abundant species community structure by high-throughput sequencing analysis.

Moving and Fixed Biological Biofilm Systems in Wastewater Treatmentwhen dose an Application Makes Sense

This study demonstrates the optimization of different Biofilm applications in wastewater treatment for a cost-effective solution. The increase of wastewater treatment cost because of high treatment efficiency requested and energy consumption makes such applications very interested in this field. Therefore, aerated reactors for wastewater treatment units were designed to work as Submerged Fixed Biofilm Bed, on the basis of biofilm-microorganisms attached to monolithic plastic supports to increase the treatment efficiency. This application depends on the aerobic process and achieved by the aeration in BOD reduction and Nitrifications reactors (Oxidation of organic compounds and nitrification). This was implemented by mixing and transport treatment processes within the biofilm attached to the plastic fixed media. The anaerobic reactor in this study was designed also to be simultaneous the de-nitrification stage by the application of a moving bed de-nitrification reactor which was considered as a part of the wastewater treatment process to achieve high treatment efficiency for the study pilot plant. The one-year-scientific evaluation was conducted onsite for the municipal wastewater pilot plant includes a test series with well-defined treatment parameters (soft mixing of the suspending the moving bed carriers; intermediate solids removal unit prior to the nitrification reactors; the mechanism for preventing the carriers to move with the flow into the subsequent reactor) such as waste-water-flow, quality, temperature, salinity, organic and hydraulic load and extensive sampling). The above application of the compact-container-system is considered as a typical field of application, for the following reasons: Need of quality improvements discharged into water body, which is often in the vicinity of bathing beaches; Need for Nutrient-Removal-Systems to avoid algae growth going into water bodies and; Space limitations in a resort and saving the implementation capital cost). The comparison between the application of the biofilm concept and the activated sludge system saved more than 40% tank size; 85% space/area; and up to 30% construction cost.

Wastewater Treatment by Using Biofilm Technologies as a Low-Cost Solution for Rural Areas

The increase of demands on treatment efficiency and cost effective solution for municipal and Industrial wastewater treatment technologies leads to new interest in the biofilm technology. Different fixed growth biofilm reactors are commercially used to increase wastewater treatment efficacy, saving space and energy. Aerated Submerged Fixed Biofilm Bed (SFBB) reactors work based on biofilms attached to plastic supports. Mixing and transport processes within the fixed media are achieved by the aeration in aerobic systems (oxidation of organic compounds and nitrification), and denitrification can be realized in anoxic conditions. The concept of application the moving bed in this study for denitrification reactor (MBDR) has been considered as a viable extension of the capabilities of a SFBB plant in the anaerobic-denitrification stage. Therefore, this novel study was implemented as pilot hybrid-reactor-container-plant to treat municipal wastewater of 200 PE, based on a combination of an aerated submerged fixed bed biofilm (SFBB) and an anoxic moving bed denitrification (MBDR) reactor. The one-year evaluation of this concept shows high nitrification, denitrification rates and, BOD reduction; by controlling the effluent (BOD5≤10 mg/l, COD ≤100 mg/l, TSS: ≤25 mg/l, NH4-: ≤2 mgN/l, NO3≤10 mgN/l)). However, Implementing of certain novel elements leads to improve operation process: (Mixing, intermediate solids removal unit, applicability of Moving bed for denitrification and submerged fixed film in aerobic reactor..etc).

In-situ fixed bed denitrification in sequential biofiltration: laboratory testing of solid substrates

Abstract High nitrate concentrations in wastewater treatment plant effluents and aquifers can challenge sequential biofiltration systems in preventing nitrite and gas formation in the sand bed, as well as to achieve the regulated limit value for nitrate in potable water reuse applications. This study investigates the introduction of electron donors in the form of organic fixed bed materials as an in-situ anoxic zone into sequential biofiltration systems. Laboratory batch and column tests with straw, soft wood, peat, polylactic acid (PLA), and polycaprolacton (PCL) revealed incomplete denitrification with a hydraulic retention time below 10 h, high organic carbon leaching, especially during the first three months, and gas accumulation within the filter bed. Therefore, ex-situ denitrification prior to oxic biofilters or in a defined side-stream treatment is recommended. No enhanced transformation of trace organic chemicals was observed under nitrate reducing conditions. Peat revealed a sorption potential for 5-methyl-benzotriazole, carbamazepine, benzotriazole, and metoprolol.

A pilot-scale deep bed denitrification filter for secondary effluent treatment using sodium acetate as external carbon.

A pilot-scale quartz sand deep bed denitrification filter (DBDF) using sodium acetate as the additional carbon source was implemented to treat secondary effluent, with a high nitrate nitrogen (NO3 -N) concentration and low C/N ratio, from an urban municipal water resource recovery facility. By the 18th day, results showed that the removal efficiency of NO3 -N and the chemical oxygen demand (COD) were stable at above 85% and 70%, respectively. When the filter layer depth was set to 1,600mm and the concentration of additional sodium acetate was maintained at 51mg/L, the total nitrogen and COD concentrations of the DBDF effluent were stabilized below 5 and 30mg/L, respectively. The quartz sand DBDF had a good effect on the removal of dissolved organic matter, especially for aromatic protein-like and tryptophan protein-like substances. Bacteria with denitrification function, such as Cloacibacterium and Zoogloea, became increasingly dominant with increasing filling layer depth. PRACTITIONER POINTS: The denitrification filter had a good effect on the removal of aromatic protein-like and tryptophan protein-like substances. Cloacibacterium and Zoogloea became increasingly dominant with increasing filling layer depth.

Denitrification process of deep bed denitrification filter for secondary effluent from urban sewage treatment plant

In recent years, the sewage discharge standards are getting stricter, and advanced wastewater treatment is more important. Therefore, further advanced treatment of the effluent from the wastewater treatment plant has become a research hotspot. In this study, deep bed denitrification filter (DBDF) was used to treat secondary effluent from urban sewage treatment plants. The effects of different carbon and nitrogen ratios (C/N) and hydraulic retention time (HRT) on the nitrogen removal efficiency of the system were investigated. The results showed that the optimum C/N of the reactor was 5, and the optimum HRT was 0.5h. After running for 15 days under the optimal conditions, the results showed that DBDF ran stably, and the denitrification effect was good. The average effluent concentrations of COD and TN were 16.4 and 6.9mg/L, and the average removal rates were 77.0% and 57.7% respectively.

Development of model simulation based on BioWin and dynamic analyses on advanced nitrate nitrogen removal in deep bed denitrification filter.

A pilot-scale deep bed denitrification filter using quartz sand as the filter media was operated under filtration velocity of 5.23m/h. Nitrate, nitrite, ammonia, and total nitrogen removal rates were relatively high at influent C/N ratios of 4:1 and 5:1. A model was developed using software to simulate the processes operating in the filter and improve the related parameters in the actual operations. The normalized sensitivity coefficient and the mean square sensitivity measure were used for the sensitivity analysis. Results showed that the stoichiometric parameters were the most sensitive, which were related to methylotrophs and biofilm. Measured data were consistent with the simulations. Moreover, the order of significance of factors affecting nitrate nitrogen removal was as follows: influent chemical oxygen demand, influent nitrate nitrogen, and hydraulic retention time. Last, the denitrification dynamic model was obtained at influent C/N ratio of 5:1.

Advanced nitrogen removal from municipal wastewater treatment plant secondary effluent using a deep bed denitrification filter.

With the improvement of wastewater discharge standards, wastewater treatment plants (WWTPs) are continually undergoing technological improvements to meet the evolving standards. In this study, a quartz sand deep bed denitrification filter (DBDF) was used to purify WWTP secondary effluent, utilizing high nitrate nitrogen concentrations and a low C/N ratio. Results show that more than 90% of nitrate nitrogen (NO3-N) and 75% of chemical oxygen demand (COD) could be removed by the 20th day of filtration. When the filter layer depth was set to 1,600 mm and the additional carbon source CH3OH was maintained at 30 mg L-1 COD (20 mg L-1 methanol), the total nitrogen (TN) and COD concentrations of DBDF effluent were stabilized below 5 and 30 mg L-1, respectively. Analysis of fluorescence revealed that DBDF had a stronger effect on the removal of dissolved organic matter (DOM), especially of aromatic protein-like substances. High throughput sequencing and qPCR results indicate a distinctly stratified microbial distribution for the main functional species in DBDF, with quartz sand providing a good environment for microbes. The phyla Proteobacteria, Bacteroidetes, and Chloroflexi were found to be the dominant species in DBDF.

The “self cleaning inherent gas denitrification-reactor” for nitrate elimination in RAS for pike perch (Sander lucioperca) production

Denitrification reactors have proven their functionality in commercial recirculation aquaculture systems (RAS). Nevertheless, clogging occurs due to the low hydraulic loads necessary to accomplish anoxic conditions for a successful denitrification process in RAS, which hampers the adjustment of stable working conditions within fixed bed denitrification reactors. Reactors working on the basis of activated sludge demand careful hydraulic control and/or complex configurations for sludge retention.To develop a low-maintenance denitrification reactor, an enclosed moving bed filter, driven by recirculation of the inherent, oxygen poor gas was designed. A Self cleaning Inherent gas Denitrification reactor (SID-reactor) of 0.65m3, which offered a moving bed volume of 0.39 m3 was connected with a RAS of semi-industrial scale for pike perch (Sander lucioperca) production. This species indicates suboptimal environmental conditions (as e.g. NO3-N concentrations above approximately 68mgl−1) by prompt reduction of the feed intake. In different experimental series, the SID-reactor was operated with denatured ethanol, methanol, acetic acid or glycerin as carbon sources and changing operational modes.Clogging was prevented by a 40 second inherent gas recirculation twice an hour, which provided continuous, maintenance free operation with marginal energy demand. With inlet (RAS) and outlet NO3-N concentrations in the range of 49mgl−1 and 12mgl−1, mean denitrification rates of 199g to 235g NO3-N per m3 moving bed volume and day were determined for all tested carbon sources. Negative effects on the feed intake of the reared pike perch were detected with all carbon sources except methanol. Changing the mode of operation to continuous circulation of the filter bed at inlet NO3-N concentrations of 26mgl−1, the denitrification performance reached 451g NO3-N per m3 moving bed volume and day. The SID-reactor allowed for the reduction of freshwater exchange in the pike perch RAS from 600 l to 70 l (−88%) and the sodium bicarbonate buffer from 182g to 31g (−83%) per kg of administered food. The easy and reliable operation of the SID-reactor could help to establish controlled denitrification as a routine purification step in RAS.

Full-scale operating experience of deep bed denitrification filter achieving <3 mg/l total nitrogen and <0.18 mg/l total phosphorus

The Arlington County Wastewater Pollution Control Plant (ACWPCP) is located in the southern part of Arlington County, Virginia, USA and discharges to the Potomac River via the Four Mile Run. The ACWPCP was originally constructed in 1937. In 2001, Arlington County, Virginia (USA) committed to expanding their 113,500 m³/d, (300,000 pe) secondary treatment plant to a 151,400 m³/d (400,000 pe) to achieve effluent total nitrogen (TN) to <3 mg/l and total phosphorus (TP) < 0.18 mg/l. Key to this conversion was the implementation of deep bed denitrification filters to simultaneously achieve both low effluent TN and TP concentrations. A challenge with implementing this technology is maintaining a health denitrifying biomass within the denitrification filters while reducing an essential nutrient, phosphorus, to very low concentrations. This paper will review the steps from concept to the first year of operation, including pilot and full-scale operating data and the capital cost for the denitrification filters.

Can We Operate Deep Bed Denitrification Filters With Limited Phosphorus?

Can We Operate Deep Bed Denitrification Filters With Limited Phosphorus?

Can We Operate Deep Bed Denitrification Filters with Limited Phosphorus?

Can We Operate Deep Bed Denitrification Filters with Limited Phosphorus?

Considerations for Alternative Supplemental Carbon Sources in Deep Bed Denitrification Filters to Achieve Low Effluent Nutrient Concentrations

Considerations for Alternative Supplemental Carbon Sources in Deep Bed Denitrification Filters to Achieve Low Effluent Nutrient Concentrations

Calibration and identifiability analysis of a water quality model to evaluate the contribution of different processes to the short-term dynamics of suspended sediment and dissolved nutrients in the surface water of a rural catchment

A method that combines calibration and identifiability analysis of a dynamic water quality model to evaluate the relative importance of various processes affecting the dynamic aspects of water composition is illustrated by a study of the response of suspended sediment and dissolved nutrients to a flood hydrograph in a rural catchment area in the Netherlands. Since the water quality model simulates the observed concentrations of suspended sediment and dissolved nutrients reasonably well, the most important processes during the observed flood hydrograph could be determined. These were erosion, exchange between dissolved phase and bed sediments and denitrification. It is concluded that the method is very useful for identifying the most significant model parameters and processes that are essential for water quality modelling. © 1998 John Wiley & Sons, Ltd.

Fluid bed biological nitrification and denitrification in high salinity wastewater

Wastewater from wet lime(stone)-gypsum flue gas desulphurisation (FGD) processes in coal-fired power plants contains nitrate. Where case selective catalytic reduction (SCR) of NO x is applied the wastewater can also contain ammonia. For the removal of both nitrate and ammonia, biological processes are an attractive option. A bottle-neck for application of biological processes might be the high chloride concentration and relatively high temperature of the wastewater. Therefore research work was performed in fluid-bed reactors at pilot-plant scale for both biological nitrification and denitrification. Biological nitrification was studied up to 34 gCl − /l and nitrite was the main product formed. Biological denitrification was effective up to at least 45 gCl − /l. Both nitrate and nitrite were removed effectively.

Simultaneous sulfide and acetate oxidation in a denitrifying fluidized bed reactor—II. Measurements of activities and conversion

An experimental set-up for the measurement of the biological activity of intact, fragile biomass particles in the presence of volatile substrates was used for the study of biomass taken from a fluidized bed denitrification reactor in which both acetate and sulfide were oxidized (see Part I). The biomass in this reactor consists of a thick (1–2 mm), fragile layer of biomass that develops on the suspended sand particles (0.5 mm). Conversion rates calculated from the activity measurements were in good agreement with concentration profiles observed in the fluidized bed reactor. The oxidation of elemental sulfur, an intermediate of the sulfide oxidation, to sulfate was the rate limiting step in both the activity measurements and the reactor. Short-term pulses of acetate and sulfide to the fluidized bed reactor confirmed the overcapacity for sulfide to sulfur and acetate oxidation. Omitting sulfide or acetate during an activity experiment did not result in different behaviour. Experiments in which nitrate depletion occurred showed that elemental sulfur could be used both as electron donor (oxidation to sulfate) and as electron acceptor (reduction to sulfide), while another electron donor in the particles, probably an organic polymer, remains to be identified. Activity measurements with nitrite as an electron acceptor showed an increased sulfur formation and nitrite concentrations in the reactor should therefore be kept as low as possible to ensure optimal performance of the system. Thiosulfate could readily be oxidized while propionate, although oxidized without a lag-period, led to the formation of nitrite. The versatility of conversions performed by the biomass represents either a large diversity of microorganisms or a relatively small group of very versatile organisms. Thiosphaera pantotropha, an organism isolated from the pilot plant version of this system, is an example of the latter group and further studies on the microbial composition may reveal more organisms of this type.

Process Analysis of Fluidized Bed Biofilm Reactor for Denitrification

A mathematical model is proposed herein to describe the dynamic behavior of the denitrification process in a fluidized bed biofilm reactor. The model basically consists of the following four submodels: bioparticles fluidization, bulk liquid flow pattern, substrate conversion within biofilm and biofilm thickness development. As for intrinsic denitrification reaction, a consecutive two-step reaction kinetics with nitrite as an intermediate product is adopted. All parameters needed for simulation were experimentally determined. Verification of the model was obtained in a dynamic state using a laboratory-scale fluidized bed denitrification reactor under well defined conditions.

Modeling, Optimization and Design of Fluidized Beds for Biological Denitrification

A mathematical model for fluidized bed denitrification has been derived, based on the fluidization theory and on zero order kinetics for biological nitrate reduction with nitrite as an intermediate product. Bed expansion, particle size, sludge concentration and nitrate and nitrite concentration can be calculated as a function of the height in the bed. Complete optimal conditions were not found using carrier materials of various specific gravities and with sizes above a radius of 0.2 mm, which was arbitrarily chosen as the smallest carrier particle. However, for each size and type of carrier material an optimal thickness of the biomass layer has been calculated for a standard type of wastewater at constant flow rate. For the kinetic and other constants used in this study, graphs are presented which can be used in the design of fluidized beds for denitrification.

Biological denitrification in a fluidized bed with sand as carrier material

A mathematical model for biological fluidized bed denitrification was tested in a 400 l h −1 expanded bed. Nitrate proved to inhibit the nitrite-reductase activity. Competitive inhibition showed a better correspondence between theory and experiment than uncompetitive inhibition. The efficiency of the fluidized bed for denitrification purposes was much higher than in the case of conventional mixed liquor processes. Both theory and experiments showed a substantial accumulation of the intermediary product nitrite, a potential health hazard. Nitrite-N maxima in the column were determined analytically and amounted to about 20% of the influent nitrate-N concentration.