scholarly journals Enhancing Denitrification in Constructed Wetland with Algae Addition

2021 ◽  
Author(s):  
Shuiping Cheng ◽  
Jing Huai ◽  
Fei Zhong ◽  
Juan Wu ◽  
Shaole Yu
Keyword(s):  
Carbon Source ◽  
Nitrogen Removal ◽  
Oxygen Demand ◽  
Dry Weight ◽  
Tertiary Treatment ◽  
Nitrite Reductase Gene ◽  
Reductase Gene ◽  
Nitrogen Concentrations ◽  
Nitrite Oxidoreductase ◽  
Anoxic Environment

Abstract Constructed wetlands (CWs) can be used for tertiary treatment of wastewater; however, carbon source shortages limit denitrification. We studied the effect of algae addition as an external carbon source in CWs and found that the nitrogen removal efficiency of CWs is highly dependent on the algae dosage. Optimal nitrogen removal can be achieved by adding 80 mg·L− 1 dry weight algae to the influent when the chemical oxygen demand/nitrogen (COD/N) ratio reaches 5.3. Longitudinal changes in the nitrogen concentrations, organic matter concentrations, and nitrogen functional genes were also analyzed. The algae addition strengthened the anoxic environment, boosted the volatile fatty acid concentrations, and proliferated the nitrite reductase gene (nirS) and the nitrite oxidoreductase alpha subunit gene (nxrA), thereby expanding the active space for denitrification. The integration of algal ponds with CWs could potentially provide enough carbon to enhance denitrification during treatment of wastewater with a low COD/N ratio.

scholarly journals Effects of Oenanthe javanica on Nitrogen Removal in Free-Water Surface Constructed Wetlands under Low-Temperature Conditions

2019 ◽  
Vol 16 (8) ◽  
pp. 1420 ◽  
Author(s):  
Song ◽  
Wang ◽  
Liu ◽  
Zhao ◽  
An
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Nitrite Reductase ◽  
Water Surface ◽  
Eastern China ◽  
Free Water ◽  
Free Water Surface ◽  
Nitrite Reductase Gene ◽  
Reductase Gene ◽  
Oenanthe Javanica

To investigate the role and microorganism-related mechanisms of macrophytes and assess the feasibility of Oenanthe javanica (Blume) DC. in promoting nitrogen removal in free-water surface constructed wetlands (FWS-CWS) under low temperatures (<10 °C), pilot-scale FWS-CWS, planted with O. javanica, were set up and run for batch wastewater treatment in eastern China during winter. The presence of macrophytes observably improved the removal rates of ammonia nitrogen (65%–71%) and total nitrogen (41%–48%) (p < 0.05), with a sharp increase in chemical oxygen demand concentrations (about 3–4 times). Compared to the unplanted systems, the planted systems not only exhibited higher richness and diversity of microorganisms, but also significantly higher abundances of bacteria, ammonia monooxygenase gene (amoA), nitrous oxide reductase gene (nosZ), dissimilatory cd1-containing nitrite reductase gene (nirS), and dissimilatory copper-containing nitrite reductase gene (nirK) in the substrate. Meanwhile, the analysis of the microbial community composition further revealed significant differences. The results indicate that enhanced abundances of microorganisms, and the key functional genes involved with nitrogen metabolism in the planted systems played critical roles in nitrogen removal from wastewater in FWS-CWS. Furthermore, abundant carbon release from the wetland macrophytes could potentially aid nitrogen removal in FWS-CWS during winter.

Using excess sludge as carbon source for enhanced nitrogen removal and sludge reduction with hydrolysis technology

2010 ◽  
Vol 62 (7) ◽  
pp. 1536-1543 ◽  
Author(s):  
Yong-Qing Gao ◽  
Yong-Zhen Peng ◽  
Jing-Yu Zhang ◽  
Jian-Long Wang ◽  
Liu Ye
Keyword(s):  
Carbon Source ◽  
Nitrogen Removal ◽  
Wastewater Treatment Plants ◽  
Reduction Rate ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Batch Reactors ◽  
Sludge Reduction ◽  
Zero Order Kinetics ◽  
Soluble Chemical Oxygen Demand

In order to improve the nitrogen removal efficiency and to achieve the sludge reduction in traditional wastewater treatment plants, a combined hydrolysis-anoxic-oxic (H-A-O) pilot-scaled reactor was used in this study to investigate the possibility and validity of using excess activated sludge (EAS) fermentation liquids to enhance the nitrogen removal. The results clearly showed that sludge acidification rate in fermentation reactor can reach to 43.2%. The percentages of acetic acid, propionic acid and butyric acid in the fermentation liquids were 68.4, 25.3 and 6.3%, respectively, while those in domestic wastewater were 73.0, 12.2 and 13.8%, respectively. Bioavailability of soluble chemical oxygen demand (SCOD) from fermentation liquids and domestic wastewater were investigated in batch reactors with nitrate as the electron accepter as well. The corresponding specific denitrification rates were 0.15 g NO3−-N/g VSS d−1 and 0.09 g NO3−-N/g VSS d−1. When the substances were enough, the denitrification reaction appeared to follow the zero-order kinetics. The results also showed that, when the H-A-O pilot-scaled reactor was operated continuously and sludge fermentation liquids were applied as additional carbon source in the A-O reactor, the removal efficiencies of SCOD, NH4+-N and total nitrogen (TN) were higher than 90, 95 and 79%, respectively. EAS reduction rate in this system was able to reach 40.4%, and the sludge VSS/SS ratio decreased from 0.82 to 0.59 after hydrolysis step.

Effects of organic carbon source, chemical oxygen demand/N ratio and temperature on autotrophic nitrogen removal

2014 ◽  
Vol 69 (10) ◽  
pp. 2079-2084 ◽  
Author(s):  
J. A. Sánchez Guillén ◽  
Y. Yimman ◽  
C. M. Lopez Vazquez ◽  
D. Brdjanovic ◽  
J. B. van Lier
Keyword(s):  
Carbon Source ◽  
Organic Carbon ◽  
Chemical Oxygen Demand ◽  
Nitrogen Removal ◽  
Oxygen Demand ◽  
Post Treatment ◽  
Operating Conditions ◽  
Organic Carbon Source ◽  
Anammox Process ◽  
Autotrophic Nitrogen Removal

To assess the feasibility of the Anammox process as a cost-effective post-treatment step for anaerobic sewage treatment, the simultaneous effects of organic carbon source, chemical oxygen demand (COD)/N ratio, and temperature on autotrophic nitrogen removal was studied. In batch experiments, three operating conditions were evaluated at 14, 22 and 30 °C, and at COD/N ratios of 2 and 6. For each operating condition, containing 32 ± 2 mg NH4+-N/L and 25 ± 2 mg NO2−-N/L, three different substrate combinations were tested to simulate the presence of readily biodegradable and slowly biodegradable organic matter (RBCOD and SBCOD, respectively): (i) acetate (RBCOD); (ii) starch (SBCOD); and (iii) acetate + starch. The observed stoichiometric NO2−-N/NH4+-N conversion ratios were in the range of 1.19–1.43, and the single or simultaneous presence of acetate and starch did not affect the Anammox metabolism. High Anammox nitrogen removal was observed at 22 °C (77–84%) and 30 °C (73–79%), whereas there was no nitrogen removal at 14 °C; the Anammox activity was strongly influenced by temperature, in spite of the COD source and COD/N ratios applied. These results suggest that the Anammox process could be applied as a nitrogen removal post-treatment for anaerobic sewage systems in warm climates.

The treatment trilogy of floating filters: from pilot to prototype to plant

1994 ◽  
Vol 29 (10-11) ◽  
pp. 23-32 ◽  
Author(s):  
H. Toettrup ◽  
F. Rogalla ◽  
A. Vidal ◽  
P. Harremoes
Keyword(s):  
Carbon Source ◽  
Oxygen Concentration ◽  
Nitrogen Removal ◽  
Nitrate Removal ◽  
Full Scale ◽  
Small Scale ◽  
Tertiary Treatment ◽  
Removal Rates ◽  
Plant Uses ◽  
Limiting Parameters

The basic kinetic expressions developed in non-aerated biofilms (denitrification and RBCs) were verified on granular floating media in aerated filters. The limiting parameters of biofilms were verified on a small scale lab unit, using wastewater and media from full scale. It could be shown that the observed relationships corresponded to theoretical expectations and half-order kinetics as well as the significant constants were established. Maximum surface removal rates were measured as 1.7 g N-NH4/m2 d for nitrification, and the most limiting parameter was a half-order oxygen concentration close to saturation. Similar kinetics as on small scale were observed on a full-scale prototype of a new floating aerated biofilter, which can be used for both nitrification and denitrification, as well as complete nitrogen removal from settled wastewater in one reactor. The mixed biofilm nitrified 15 % less than pure tertiary treatment, and 20 % performance was lost between lab and full scale, due mainly to aeration limitations. Also, 35 % lower denitrification rates were observed between ethanol and sewage as carbon source, but addition of ethanol raised the full-scale performance to nitrate removal rates of 1,4 g N-NO3/m2 d. After pilot testing and full-scale demonstration, the process was implemented on several treatment plants, one of which was located in Denmark, to achieve nitrogen residuals below 8 mg TN/1. This plant uses 8 filters of 63 m2 to treat 12 000 m3/d, and the biological reactor occupies a surface similar to the existing conventional primary settler. The results of the first few months of operation are given: as long as the ratio between biodegradable COD and total nitrogen at the filter inlet is above 5, nitrogen removal of 80 % is achieved.

scholarly journals Effect of adding microorganism and carbon source to substrate on nitrogen removal treating the drainage of WWTP

2019 ◽  
Vol 79 (10) ◽  
pp. 1947-1955 ◽  
Author(s):  
Han Wei ◽  
Li Ting-mei ◽  
Cheng Lu-lu ◽  
Liu Lu ◽  
Yu Lu-ji ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Carbon Source ◽  
Nitrogen Removal ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Order Kinetic ◽  
Release Process ◽  
Carbon Release ◽  
The Difference ◽  
Excellent Property

Abstract Developing substrate with carbon release properties is helpful to enhance nitrogen removal in low C/N ratio wastewater treatment. In this study, substrates with and without adding carbon source and microorganism were prepared to treat the drainage effluent from a wastewater treatment plant (WWTP), the difference in nitrogen removal were investigated. The results showed that adding a carbon source and microorganism to substrates could not only increase the amount of chemical oxygen demand (COD) released, but also enhance the adsorption capacities of NH4+-N and NO3–-N. The carbon release process followed the first-order kinetic equation. A nitrogen removal model consisting of four phases of diffusion, adsorption, assimilation and transformation was proposed. In the short term, nitrogen was mainly removed by adsorption; adding microorganism contributed to enhance nitrification and denitrification. In the long-term, nitrogen removal performances were similar whether microorganism was added or not, and microbial species on the surface of substrates were similar. This work suggested when using substrate to treat wastewater for nitrogen removal, preparing a substrate with excellent property for biofilm formation was the most important factor.

Regulating Strategies of Strengthening Nitrogen Removal for Low-Carbon Wastewater in Reversed A2/O Process

2011 ◽  
Vol 243-249 ◽  
pp. 4811-4816 ◽  
Author(s):  
Jie Yun Chen ◽  
Zhi Zhang ◽  
Li Hua Xie ◽  
Ling Kong ◽  
Xiao Jing Yin
Keyword(s):  
Low Temperature ◽  
Carbon Source ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Experimental Studies ◽  
Reflux Ratio ◽  
Low Carbon ◽  
Efficient Operation ◽  
Anoxic Environment ◽  
Aerobic Zone

According to the ineffective denitrification and the initial controlling technique flaws for low-carbon source in reversed A2/O process, and full scale experimental studies were conducted to strengthen denitrification at normal and low temperature days in 2008~2010, to ensure the best conditions of biological denitrification and promote the stable and efficient operation of the system. The results showed that in normal temperature seasons of 2008, after shortening the HRT of the primary sedimentation tank to 1/3 of design value, improving the MLSS to 4500mg/L, setting the first section of the aerobic zone as the denitrification transition section and improving the reflux ratio, available carbon source was increased by 15%, the effluent NH3-N was 2.5mg / L and the removal rate was 90%, the effluent TN was 17 mg/L and the removal rate was increased to 54% and unit power consumption was reduced by 15% to 0.22Kw•h/m3.At low temperature seasons of 2008~2009,by improving the MLSS to 6000mg/L, extending the sludge age to enrich a large number of nitrification and denitrification bacteria, controlling DO at about 1.2mg / L in the aerobic zone and so on, the effluent NH3-N was 3 mg / L and the removal rate was 88%, the effluent TN was 15.5 mg/L and the removal rate was 62%. In low temperature of 2009 ~2010, besides the same measures as before, adding a blender in the first section of the aerobic zone to provide a better anoxic environment for denitrification and to improve nitrogen removal, the effluent NH3-N was 3 mg / L and the removal rate was 87%, the effluent TN was 13.5 mg/L and the removal rate was 66%.

Molecular Cloning and Characterization of Nitrite Reductase Gene from Sugarbeet

2011 ◽  
Vol 37 (8) ◽  
pp. 1406-1414
Author(s):  
Xiao-Yan SHI ◽  
Yan-Da ZENG ◽  
Shi-Long LI ◽  
Yu-Bo WANG ◽  
Feng-Ming MA ◽  
...  
Keyword(s):  
Molecular Cloning ◽  
Nitrite Reductase ◽  
Nitrite Reductase Gene ◽  
Reductase Gene

Pre-Precipitation Facilitates Nitrogen Removal without Tank Expansion

1990 ◽  
Vol 22 (7-8) ◽  
pp. 85-92 ◽  
Author(s):  
Ingemar Karlsson ◽  
Gunnar Smith
Keyword(s):  
Waste Water ◽  
Organic Matter ◽  
Water Treatment ◽  
Carbon Source ◽  
Nitrogen Removal ◽  
Waste Water Treatment ◽  
Chemical Precipitation ◽  
Sewage Water ◽  
Laboratory Studies ◽  
Denitrification Process

Chemically coagulated sewage water gives an effluent low in both suspended matter and organics. To use chemical precipitation as the first step in waste water treatment improves nitrification in the following biological stage. The precipitated sludge contains 75% of the organic matter in the sewage and can by hydrolysis be converted to readily degradable organic matter, which presents a valuable carbon source for the denitrification process. This paper will review experiences from full-scale applications as well as pilot-plant and laboratory studies.

Removal of nitrogen from coal gasification wastewater by nitrosofication and denitrosofication

1998 ◽  
Vol 38 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Junxin Liu ◽  
Weiguang Li ◽  
Xiuheng Wang ◽  
Hongyuan Liu ◽  
Baozhen Wang
Keyword(s):  
Nitrogen Removal ◽  
Coal Gasification ◽  
Oxygen Demand ◽  
Test Results ◽  
New Process ◽  
Scale Test ◽  
Coal Gasification Wastewater ◽  
Total Nitrogen Removal ◽  
Biological Nitrogen ◽  
Bench Scale Test

In this paper, a study of a new process with nitrosofication and denitrosofication for nitrogen removal from coal gasification wastewater is reported. In the process, fibrous carriers were packed in an anoxic tank and an aerobic tank for the attached growth of the denitrifying bacteria and Nitrobacter respectively, and the suspended growth activated sludge was used in an aerobic tank for the growth of Nitrosomonas. A bench scale test has been carried out on the process, and the test results showed that using the process, 25% of the oxygen demand and 40% of the carbon source demand can be saved, and the efficiency of total nitrogen removal can increase over 10% as compared with a traditional process for biological nitrogen removal.

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