Nutrient Removal Kinetics Research Articles

Removal and recovery of nutrients from septic tank wastewater using microalgae: Key factors and practical implications

Treatment of septic tank wastewater (STWW) with high concentrations of ammonium (NH4+) and total phosphorus (TP), is challenging in decentralized areas. Utilizing microalgae for STWW treatment can simultaneously recover nutrients in the form of high-value microalgal biomass. However, despite the potential benefits, microalgal treatment of STWW is rarely reported. Therefore, this work utilized bench-scale photobioreactors (PBR) to investigate different factors that could affect microalgal cultivation in STWW and treatment efficiency. Accordingly, it was observed that suspended solids present in STWW did not significantly affect the microalgae growth and nutrient removal efficiencies in bubble column PBR. On the other hand, the effect of endemic microorganism could not be verified in this study due to observed fungal contamination and change in nutrient profile of STWW after autoclave. Nevertheless, the highest microalgal growth and nutrient removal efficiencies of NH4+-N = 79.14% and TP = 41.11% were observed within 14 days of photoautotrophic cultivation in raw STWW. Further, 25 days of upscaled photoautotrophic cultivation in 4-L bubble column PBR was performed to study biomass yield, nutrient removal kinetics, and nutrient removal efficiency. Consequently, 0.75 g‧L−1 dry biomass was produced with improved removal efficiency of NH4+-N (96.16%), and TP (69.57%). Elemental analysis of biomass revealed that 62.99 ± 1.46 mg‧L−1 TN and 11.41 ± 1.42 mg‧L−1 TP were recovered. Further, 1.02 geq carbon dioxide (CO2) was bio-fixed with every liter of STWW treated. The findings of this study revealed that microalgae can be successfully utilized for the removal and recovery of nutrients from STWW.

Nutrient removal from stormwater in floating treatment wetlands: prediction of kinetic rates, effect of initial concentration and plant performance assessment

Plant dry biomass normalised by water volume predicts nutrient removal kinetics.

Kinetics of Nutrient Removal in an Integrated Suspended Growth Reactor

Wastewater effluent discharge in a large amount of ammonia, nitrate and phosphorus lead to eutrophication the river. Eutrophication is a serious environmental issue that threaten the fishes and aquatic plants. To prevent this from happening, ammonia produced in STP and raw wastewater removal is achieved during nitrification by having an extended aeration while nitrate removal is achieved during denitrification in anoxic tank. In this research study, a pilot plant of integrated suspended growth system (i-SGS) reactor was used to achieve simultaneous removal of ammonia and nitrate. The reactor has three main compartments which are anoxic chamber, aeration camber, and clarifier and operated at a constant flow rate of 720 L/d and fixed SRT of 40 days. The RAS time was set to once every 10 minutes for 5 minutes while the IR time is once every 16 minutes for 5 minutes. The wastewater quality parameters, namely chemical oxygen demand (COD), ammonia, and nitrate were measured to determine and evaluate the removal efficiency of them in i-SGS whereas phosphorus was measured to ensure the effluent standard meet the C:N:P ratio requirement. Samples from four sampling points were taken to conduct the laboratory experiment and three replication of the results for each parameter were measured. It was determined that i-SGS was able to eliminate average 72% of COD at 46 mg/L of clarifier effluent, and achieved 95% of ammonia removal at average 1.22 mg/L of the clarifier effluent concentration while obtained 43% of nitrate removal in the anoxic tank. Last but not least, the C:N:P ratio obtained was 100:14:8, denoted that i-SGS has ample of nutrients loading provided because it is more than the minimum nutrient requirements, 100:5:1. The removal was possible through the nitrification-denitrification process in the i-SGS pilot plant bioreactor. The operational SRT of 40 days have shown to be effective and stable for the COD but not for nitrifiers. The effluent discharge of COD, ammonia and nitrate in the pilot plant i-SGS has meet the standard requirement of DOE Malaysia, standard A and B respectively.

Nutrient removal through pyrrhotite autotrophic denitrification: Implications for eutrophication control

This study investigated nutrient removal kinetics and main influencing factors of natural pyrrhotite autotrophic denitrification (PAD), and nutrient removal performance and the microbial community in the PAD biofilter (PADB). Results demonstrated that both NO3− and PO43− in wastewater were nearly completely removed, and biological N removal and chemical P removal took place simultaneously in the PAD process. NO3− removal kinetics of the PAD can be described with half-order kinetics. The PAD was effective across a wide temperature range of 11–34 °C, initial NO3−-N range of 13–52 mg·L−1 and PO43−-P below 60 mg·L−1. Both NO3− and PO43− decreased gradually with wastewater flowing along the PADB. The PADB operation results show that at 12 h HRT, when the PADB treated wastewater containing 30.95 ± 0.97 mg·L−1 of NO3− and 3.02 ± 0.10 mg·L−1 of PO43−-P, the effluent contained 1.15 ± 2.08 and 0.09 ± 0.11 mg·L−1 of NO3−-N and PO43−-P on average, respectively. In the PADB the dominant bacteria were Thiobacillus and Sulfurimonas, which used pyrrhotite as the electron donor to reduce NO3−. The relative abundance of Thiobacillus at the bottom of the PADB increased from 0.81% to 58.65% and that of Sulfurimonas decreased from 97.22% to 12.30%, with exposure to pyrrhotite. From the bottom to the top of the PADB, the relative abundance of Thiobacillus increased from 58.65% to 86.23% and Sulfurimonas decreased from 12.30% to 0.52%. Technologies based on the PAD are promising ways to control eutrophication.

Kinetics of nutrient removal in an on-site domestic wastewater treatment facility

Domestic wastewater from office building has not been maintained well especially in the areas where the sewerage system is unavailable. The aims of this research were to investigate the performance and kinetics of nutrient removal in an on-site domestic wastewater treatment facility which consists of anaerobic and aerobic systems for treating wastewater from office building. The experimental data obtained from the variations of COD:N:P ratio 250:28:2.5, 350:38:2.9, 450:47:3.3, and 600:60:3.7 with three different HRT 48h, 24h, and 12h. A One-way ANOVA was performed to investigate the effects of HRT and initial concentration of TN and TP on the performance of nutrient removal. In order to obtain the kinetic coefficients, First Order, Second Order and Stover-Kincannon Models were employed. The results showed that maximum TN and TP removal efficiency were 56% and 86%, respectively. The results of one-way ANOVA showed that HRT and initial concentration of TN and TP gave the significant effects on nutrient removal (p < 0.05). Second Order and Stover-Kincannon Models were found to be more appropriate models for prediction of TN removal in this facility. Controlling HRT and C: N: P ratio may keep good performance of nutrient removal in this facility.

Urban wastewater photobiotreatment with microalgae in a continuously operated photobioreactor: growth, nutrient removal kinetics and biomass coagulation–flocculation

ABSTRACTThe aim of this study was to investigate the growth, nutrient removal and harvesting of a natural microalgae bloom cultivated in urban wastewater in a bubble column photobioreactor. Batch and continuous mode experiments were carried out with and without pH control by means of CO2 dosage. Four coagulants (aluminium sulphate, ferric sulphate, ferric chloride and polyaluminium chloride (PAC)) and five flocculants (Chemifloc CM/25, FO 4498SH, cationic polymers Zetag (Z8165, Z7550 and Z8160)) were tested to determine the optimal dosage to reach 90% of biomass recovery. The maximum volumetric productivity obtained was 0.11 g SS L−1 d−1 during the continuous mode. Results indicated that the removal of total dissolved nitrogen and total dissolved phosphorous under continuous operation were greater than 99%. PAC, Fe2(SO4)3 and Al2(SO4)3 were the best options from an economical point of view for microalgae harvesting.

COD and Nutrient Removal Kinetics of Piggery Wastewater in Nigeria

COD and Nutrient Removal Kinetics of Piggery Wastewater in Nigeria

Screening native microalgal consortia for biomass production and nutrient removal from rural wastewaters for bioenergy applications

In the present study, 9 native microalgae consortia were investigated for their biomass potential in both low strength rural sector wastewater, RSW (COD=310.46mgL−1; NO3-N=9.8mgL−1; TDP=26.89mgL−1; TAN=10.1mgL−1) and high strength livestock wastewater, LSW (COD=2940mgL−1; NO3-N=75mgL−1; TDP=200mgL−1; TAN=161mgL−1). In LSW, maximum biomass concentration of 1.93gDWL−1 was recorded which was significantly higher than that in standard synthetic media BG11 (1.17gDWL−1) and RSW (0.78gDWL−1). By the end of 12 day batch culture, all the native consortia showed 80–100% reduction in nutrient from the tested wastewaters under controlled conditions (temperature: 25±1°C, light intensity: 50–60μmolm−2s−1 and dark-light cycle of 12:12h). Comparative growth of algae in RSW and LSW suggest that different types of wastewater could result in different nutrient removal kinetics and growth potential of algae. The biochemical characterization of the best performing consortium, PA6 (C0.5H7.8O0.5N0.7) revealed that it was rich in protein (54%) followed by lipids (31%) and carbohydrates (10%). The estimation of theoretical methane potential (0.79m3kgVS−1) suggested that PA6 has better prospects of biogas generation. Hence, this particular consortium could be utilized for reducing the water pollution levels and generating feedstock for biofuels production. However, challenges associated with scale up and continuous operation under real conditions need to be evaluated and addressed.

Urban wastewater treatment by seven species of microalgae and an algal bloom: Biomass production, N and P removal kinetics and harvestability

This study evaluates the capacity of seven species and a Bloom of microalgae to grow in urban wastewater. Nutrient removal kinetics and biomass harvesting by means of centrifugation and coagulation–flocculation-sedimentation have been also tested. Results show that the best biomass productivities ranged from between 118 and 108 mgSS L−1 d−1 for the Bloom (Bl) and Scenedesmus obliquus (Sco). Regarding nutrient removal, microalgae were able to remove the total dissolved phosphorus and nitrogen concentrations by more than 80% and 87% respectively, depending on the species tested. The final total dissolved concentration of nitrogen and phosphorus in the culture media complies with the European Commission Directive 98/15/CE on urban wastewater treatment. Regarding harvesting, the results of coagulation–flocculation sedimentation using a 60 mg L−1 dose of Ferric chloride were similar between species, exceeding the biomass removal efficiency by more than 90%. The results of centrifugation (time required to remove 90% of solids at 1000 rpm) were not similar between species, with the shortest time being 2.9 min for Sco, followed by the bloom (7.25 min). An overall analysis suggested that the natural bloom and Scenedesmus obliquus seem to be the best candidates to grow in pre-treated wastewater, according to their biomass production, nutrient removal capability and harvestability.

Kinetics of Nutrient Removal by Nano Zero-Valent Iron under Different Biochemical Environments.

The effectiveness of nano zero-valent iron (NZVI; an average size of 55 nm at a concentration of 200 mg Fe/L) in nutrient removal was determined under anaerobic, anoxic, and aerobic conditions. Compared to the rate of reduction of nitrate nitrogen (NO3--N) to ammoniacal nitrogen (NH4+-N) by NZVI alone, the presence of activated sludge increased the rate of complete reduction by 300%. About 31% of NO3--N was converted to NH4+-N through NZVI-facilitated dissimilatory nitrate reduction to ammonium, while 56% of NO3--N was removed by heterotrophic denitrification. The presence of sludge reduced the rates of phosphorus removal by NZVI, with the first-order reaction rate constants of 0.06/hour, 0.42/hour, and 0.18/hour under anaerobic, anoxic, and aerobic conditions, respectively. The highest phosphorus removal efficiency (95%) by NZVI was observed under anoxic abiotic conditions, whereas the efficiency dropped to 31% under anaerobic biotic conditions, which was attributed to significant sludge-facilitated NZVI agglomeration.

Optimization and kinetics of nutrient removal from wastewater by chemical precipitation of struvite

Nutrient removal by the precipitation of struvite from synthetic municipal wastewater was tested. Response surface methodology with the Box–Behnken experimental design was employed to determine the optimal phosphorus removal efficiency with the influencing process variables of pH, temperature, magnesium to phosphorus molar ratio, mixing speed (rpm), and organic contents. Under the values of pH, temperature, Mg to P ratio, mixing, and organic content of 9.86, 26.5°C, 1.64, 80 rpm, and 1,020 mg sugar/l, respectively, optimum phosphorus (PO4-P) removal efficiency of 90.1% was obtained. Results of analysis of variance indicated that the quadratic model predicts the responses adequately with the five factors that coded the process variables. The effects the factors have on the amount of PO4-P removal were ranked (with their relative scores) in the descending order of pH (11.8), Mg:P ratio (6.2), organic content (2.4), mixing speed (1.1), and temperature (0.5), where the ranking quantifications were according to the respective coefficients of the factors in the quadratic model equation. Removal of nitrogen (NH4-N) was limited by equal molar amount of PO4-P removed and thus the remaining NH4-N must be subsequently treated using usual nitrogen removal processes.

Kinetics of nutrient removal and expression of extracellular polymeric substances of the microalgae, Chlorella sp. and Micractinium sp., in wastewater treatment

Two species of green algae, Chlorella sp. and Micractinium sp., were cultivated in primary effluent wastewater and high-strength wastewater (a mixture of anaerobic digestion centrate and primary effluent) to study nutrient removal and EPS (extracellular polymeric substances) expression during their growth. The high N concentration and P-limited condition in the mixed wastewater (total N=197 mg/L; N/P mass ratio=56) led to about 3 times greater specific N removal rate than the primary effluent set, indicating that algal cells growing in N-rich wastewater had N over-uptake. Both Chlorella and Micractinium grown in the high-strength wastewater also produced larger amounts of protein EPS, possibly accounting for higher N uptake in those cultivation sets. These results suggest that different types of wastewater could cause different nutrient removal kinetics and EPS expression by algae, which may subsequently influence harvesting and anaerobic digestion of their biomass.

Kinetics of nutrient removal and biomass production by duckweed Wolffia arrhiza in continuous-flow mesocosms

The nutrient removal and biomass production with duckweed Wolffia arrhiza was assessed using laboratory-scale continuous-flow mesocosms fed with model wastewater. Average removal rates of nitrogen and phosphorus by vegetative fronds were 0.03–0.18mg-N/m2/d and 0.023–0.079mg-P/m2/d, respectively. The maximum production rates of the vegetative fronds and the turions were respectively 86–160g-wet/m2/d and 55–64g-wet/m2/d, depending on the nutrient concentration. The kinetic data of the biomass and nutrient concentrations were analyzed using a mathematical model, which showed that the maximum specific growth rate of W. arrhiza was 0.35–0.38d−1, whereas the turion formation was induced when the specific growth rate decreased below 0.085–0.12d−1 in low-nitrogen conditions. The model developed in this study is applicable for predicting the wastewater treatment performance and biomass production of preferential biomass, the protein-rich vegetative fronds, the starch-rich turions, or total biomass of W. arrhiza.

EFFECT OF TEMPERATURE ON EBPR SYSTEM PERFORMANCE AND MICROBIAL COMMUNITY

EFFECT OF TEMPERATURE ON EBPR SYSTEM PERFORMANCE AND MICROBIAL COMMUNITYIt is well known and firmly established that the rate of chemical and biochemical reactions slow down as temperature decreases. Nevertheless, several studies have reported that the efficiency of enhanced biological phosphorus removal (EBPR) improves as temperature decreases. However, several recent studies have reported that EBPR reaction rates decrease with temperature decrease in accordance with...Author(s)Ufuk G. ErdalZeynep K. ErdalClifford W. RandallSourceProceedings of the Water Environment FederationSubjectSession 40 - Research Symposium: Biological Nutrient Removal Kinetics and SimulationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2002ISSN1938-6478SICI1938-6478(20020101)2002:14L.732;1-DOI10.2175/193864702784248296Volume / Issue2002 / 14Content sourceWEFTECFirst / last page(s)732 - 753Copyright2002Word count364

SIMULATION OF BIO P REMOVAL IN CFD ENVIRONMENT Analysis of Macro- Environment Variations in Simultaneous Biological Nutrient Removal Systems

SIMULATION OF BIO P REMOVAL IN CFD ENVIRONMENT Analysis of Macro- Environment Variations in Simultaneous Biological Nutrient Removal SystemsA self-consistent three-dimensional computational fluid dynamics (CFD) activated sludge model is being developed for a full-scale closed loop bioreactor. The objective of the study is to provide insights into simultaneous biological nutrient removal resulting from the reactor mixing pattern. This report investigates the effects on biological phosphorus removal. Based on ASM model No. 2,...Author(s)Helen X. LittletonGlen T. DaiggerPeter F. StromRong JinSourceProceedings of the Water Environment FederationSubjectSession 40 - Research Symposium: Biological Nutrient Removal Kinetics and SimulationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2002ISSN1938-6478SICI1938-6478(20020101)2002:14L.754;1-DOI10.2175/193864702784248386Volume / Issue2002 / 14Content sourceWEFTECFirst / last page(s)754 - 770Copyright2002Word count368

Methanol-induced biological nutrient removal kinetics in a full-scale sequencing batch reactor

The primary goal of this research was to determine the potential for denitrification and phosphorus removal of a full-scale sequencing batch reactor (SBR), with and without the use of methanol as an external carbon source. The control SBR, without methanol addition, achieved negligible denitrification. Two denitrification rates were observed in the experimental SBR, with methanol addition; an initial fast rate and a slower second rate. The denitrification rate during the first rate period increased with increasing methanol concentration, until a maximum denitrification rate of ∼19 mg NO x -N/g MLVSS/day was attained. Following the depletion of the methanol, denitrification reactions probably continued by using the available natural carbon in the influent, resulting in a slower, second denitrification rate. Biological phosphorus uptake and release was significant only in the SBR with methanol addition. Methanol was probably not utilized as the carbon source for the enhanced biological phosphorus removal (EBPR) process. However, methanol addition was critical, since it depleted the available nitrates and thus allowed EBPR to take place.

Side stream biofiltration for improved biofouling control in cooling water systems

Biological activity in open recirculating cooling water systems may lead to Microbial Induced Corrosion (MIC) and lower heat exchange efficiencies. The use of oxidizing biocides as a tool to control excessive biofilm formation in a cooling water system can be characterised as fighting the symptoms, because it does not take away the main cause of biofilm growth: the availability of nutrients. Due to frequent use of oxidizing biocides the microbial growth rate in the cooling water system studied (1–2 d−1) was even higher than the dilution rate (0.33 d−1). By means of an ASTRASAND®continuous sand filter used as a side stream biofilter it is possible to achieve considerable reductions in nutrients and in suspended biomass contents. The content of nutrients in the filter influent and effluent was expressed in terms of growth rates and was determined by batch experiments. Based on the assumptions of plug flow characteristics and first order reaction kinetics, the kinetic coefficients for nutrient removal were determined at k1=6 h−1 for fine (0.8–1.25 mm) and at k1=4.5 h−1 for coarse (1.4–2.0 mm) filter material. Due to the first order kinetics of nutrient removal and due to the improved filtration efficiencies at increasing influent biomass contents, it is concluded that a side stream biofilter introduces a self regulating process element in the cooling water system, leading to a faster recovery of the cooling water quality after upset conditions. Considerable savings in the use of oxidizing agents can be established.