scholarly journals Methane Emissions Driven by Adding a Gradient of Ethanol as Carbon Source in Integrated Vertical-Flow Constructed Wetlands

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1086
Author(s):  
Xiaoling Liu ◽  
Jingting Wang ◽  
Xiaoying Fu ◽  
Hongbing Luo ◽  
Bruce C. Anderson ◽  
...  
Keyword(s):  
Carbon Source ◽  
Constructed Wetlands ◽  
Control Experiment ◽  
Ethanol Concentration ◽  
Removal Rate ◽  
Carbon Sources ◽  
Vertical Flow ◽  
Emission Flux ◽  
Rate Range ◽  
External Carbon Source

This work aims to investigate the methane emissions from integrated vertical-flow constructed wetlands (IVCWs) when ethanol is added as an external carbon source. In this study, a gradient of ethanol (0, 2, 4, 8, 16 and 32 mmol/L) was added as the carbon source in an IVCW planted with Cyperus alternifolius L. The results showed that the methane emission flux at an ethanol concentration of 32 mmol/L was 32.34 g CH4 m−2 day−1 less than that of the control experiment (0 mmol/L) and that the methane emission flux at an ethanol concentration of 16 mmol/L was 5.53 g CH4 m−2 day−1 less than that at 0 mmol/L. In addition, variations in the water quality driven by the different ethanol concentrations were found, with a redox potential range of −64 mV to +30 mV, a pH range of 6.6–6.9, a chemical oxygen demand (COD) removal rate range of 41% to 78%, and an ammonia nitrogen removal rate range of 59% to 82% after the ethanol addition. With the average CH4-C/TOC (%) value of 35% driven by ethanol, it will be beneficial to understand that CH4-C/TOC can be considered an ecological indicator of anthropogenic methanogenesis from treatment wetlands when driven by carbon sources or carbon loading. It can be concluded that adding ethanol as an external carbon source can not only meet the water quality demand of the IVCW treatment system but also stimulate and increase the average CH4 emissions from IVCWs by 23% compared with the control experiment. This finding indicates that an external carbon source can stimulate more CH4 emissions from IVCWs and shows the importance of carbon sources during sewage treatment processes when considering greenhouse emissions from treated wetlands.

Comparative Analysis of Nitrate Removal in Sub-Surface Flow Constructed Wetlands by Different External Carbon Sources

2014 ◽  
Vol 1073-1076 ◽  
pp. 779-783
Author(s):  
Patience Awhavbera ◽  
Lian Fang Zhao
Keyword(s):  
Carbon Source ◽  
Wheat Straw ◽  
Constructed Wetlands ◽  
Nitrate Removal ◽  
Waste Product ◽  
Carbon Sources ◽  
Surface Flow ◽  
Synthetic Wastewater ◽  
External Carbon Source ◽  
N Removal

External carbon sources provide additional nutrients that improve the efficiency of nitrate removal in constructed wetlands. Typha angustifolia L. were planted in four vertical subsurface-flow constructed wetlands. Different external carbon sources were fed into the columns, to investigate and compare their treatment of nitrate in synthetic wastewater, with initial influent C/N ratio of 1:1. Wetland A (WA) with 50g wheat straw as external carbon source, wetland B (WB) with 50g woodchips, wetland C (WC) with additional 10mg/L glucose and wetland D (WD) without external carbon source to serve as the control, were used in the lab-scale experimental study. WA, WB, WC and WD within a period of 24 days, cumulatively removed 109.38mg/L, 93.75mg/L, 85.14mg/L, and 64.01mg/L nitrate, respectively, from the influent. The nitrate-nitrogen (NO3–N) removal efficiency as aided by the external carbon sources was in the order: wheat straw > woodchips > glucose > control. Wheat straw treated 93% NO3–N, woodchips 78%, glucose 72% and the control 53%. The results indicate that WA, WB and WC outperformed the control system, due to the additional carbon sources. In general, the wheat straw had a better performance than wood chips and glucose. Thus, wheat straw as low cost biological waste product is recommended for the treatment of nitrate in wetlands.

Advances of External Carbon Source in Denitrification

2012 ◽  
Vol 518-523 ◽  
pp. 2319-2323 ◽  
Author(s):  
Guang Ying Liu ◽  
Huan Zhen Zhang ◽  
Wei Li ◽  
Xin Zhang
Keyword(s):  
Carbon Source ◽  
Slow Release ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Carbon Sources ◽  
Electron Donors ◽  
Primary Sludge ◽  
External Carbon Source ◽  
The Media ◽  
Available Carbon

Carbon source used as electron donors is critical to heterotrophic denitrification. Addition of external carbon source is necessary when internal organics are deficient. A review was conducted on the use of external carbon source in denitrification. Traditional carbon sources such as methanol and ethanol, alternative carbon sources such as cellulose-rich materials, biodegradable polymers and primary sludge are included in external carbon sources. Present situation and problems of its biodegradability and effects in denitrification are summarized. Focus in external carbon source includes further study on the biodegradation mechanism of the media, slow release performance and nitrate removal rate of available carbon source and continuous research on new kinds of substrates. Recommendations on further study of carbon source are put forward.

Pollutants Removal and Analysis of Microbial Community of Malodorous River in BFG-IVCWs

2012 ◽  
Vol 518-523 ◽  
pp. 3045-3052 ◽  
Author(s):  
Yi Fan Zhang ◽  
Yong Zhang ◽  
Min Sheng Huang ◽  
Huan Xu ◽  
Yan He
Keyword(s):  
Microbial Community ◽  
Constructed Wetlands ◽  
River Flow ◽  
Flow System ◽  
Removal Rate ◽  
Vertical Flow ◽  
Environmental Condition ◽  
Pollutants Removal ◽  
Dgge Fingerprint ◽  
Structure Diversity

The changes of concentrations of pH, DO, CODCr, NH4+-N and NO3--N in Biofilm Grid-Integrated Vertical-flow Constructed Wetlands（BFG-IVCWs）by treating the urban malodorous river were measured. After 45 days, DO had its own distribution and changing regulation, the removal rate of CODCrreach to 45%, at meantime, the removal rate of NO3--N are over 50%. The diversity of microbial community and its succession were analyzed by PCR-DGGE fingerprint. The result shows: the removal rate of CODCrand NH4+-N along the river flow gradually rises, and the removal rate of NO3--N rises at last. The removal of pollutants mainly happened in the down-flow system of the BFG-IVCWs. The differences of characters of biofilm and environmental condition of different positions made the microbial community structure diversity variable. Three kinds of biofilms (W3, W5 and W7) were analyzed with Shannon-Wiener and Cs indices and the value in position W3 was the highest.

scholarly journals Enhance nitrogen removal in bioretention cells with addition of hydrothermal pre-treated pine barks as external carbon source

2021 ◽  
Author(s):  
Jing Tuo ◽  
Shiwei Cao ◽  
Muzi Li ◽  
Rong Guo
Keyword(s):  
Carbon Source ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Common Factor ◽  
Nutrients Removal ◽  
Fiber Structure ◽  
Effluent Quality ◽  
External Carbon Source ◽  
Carbon Release ◽  
Cod Removal Rate

Abstract The problem of poor carbon source is a common factor limiting the nutrients removal in bioretention cells (BRCs). This study aimed to investigate the feasibility of using modified biomass in BRCs filled with a mixture of fly ash ceramsite and pumice fillers to enhance nitrogen removal. Different pretreatment methods (hydrothermal-treated, acid-treated and alkali-treated) were attempted, and hydrothermal pretreatment showed a best performance in carbon release ability. The scanning electron microscopy showed that the lignin in hydrothermal pretreated pine barks (H-PBs) was destroyed, and the fiber structure became thinner with more irregular folds, which improved the accessibility of cellulose and attachment of microorganisms. The addition of H-PBs significantly enhanced the nutrients removal in BRCs, and the removal rates of TN and NO3−-N increased by 23.25% and 38.22% compared with those in BRC-A (without external carbon source), but the removal rate of NH4+-N was inferior to BRC-A. Besides, the large carbon release amount of H-PBs did not deteriorate the effluent quality, with COD removal rate of 87.98% in the 48 d. These results indicate that the BRCs by adding H-PBs could intensify the denitrification process.

scholarly journals Effect of the Influent Substrate Concentration on Nitrogen Removal from Summer to Winter in Field Pilot-Scale Multistage Constructed Wetland–Pond Systems for Treating Low-C/N River Water

2021 ◽  
Vol 13 (22) ◽  
pp. 12456
Author(s):  
Tao Wang ◽  
Liping Xiao ◽  
Hongbin Lu ◽  
Shaoyong Lu ◽  
Xiaoliang Zhao ◽  
...  
Keyword(s):  
River Water ◽  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Substrate Concentration ◽  
Removal Rate ◽  
Carbon Sources ◽  
River Estuary ◽  
Pilot Scale ◽  
Surface Flow

The quality of micropolluted water is unstable and its substrate concentration fluctuates greatly. The goal is to predict the concentration effect on the treatment of nitrogen in a river with an actual low C/N ratio for the proposed full-scale Xiaoyi River estuary wetland, so that the wetland project can operate stably and perform the water purification function effectively in the long term. Two pilot-scale multistage constructed wetland–pond (MCWP) systems (S1 and S2, respectively) based on actual engineering with the same “front ecological oxidation ponds, two-stage horizontal subsurface flow constructed wetlands and surface flow constructed wetlands (SFCWs) as the core and postsubmerged plant ponds” as the planned process were constructed to investigate the effect of different influent permanganate indexes (CODMn) and total nitrogen (TN) contents on nitrogen removal from micropolluted river water with a fixed C/N ratio from summer to winter in the field. The results indicate that the TN removal rate in the S1 and S2 systems was significant (19.56% and 34.84%, respectively). During the process of treating this micropolluted water with a fixed C/N ratio, the influent of S2 with a higher CODMn concentration was conducive to the removal of TN. The TN removal rate in S2 was significantly affected by the daily highest temperature. There was significant nitrogen removal efficiency in the SFCWs. The C/N ratio was a major determinant influencing the nitrogen removal rate in the SFCWs. The organic matter release phenomenon in SFCWs with high-density planting played an essential role in alleviating the lack of carbon sources in the influent. This research strongly supports the rule that there is seasonal nitrogen removal in the MCWPs under different influent substrate concentrations, which is of guiding significance for practical engineering.

Effect of External Carbon Source on Denitrification in Biofilter at Low Temperature

2010 ◽  
Vol 113-116 ◽  
pp. 1358-1362
Author(s):  
Hong Jun Han ◽  
Yu Fei Li ◽  
Hong Bo Hu ◽  
Bing Wang
Keyword(s):  
Low Temperature ◽  
Carbon Source ◽  
Carbon Sources ◽  
Efficiency Enhancement ◽  
Denitrification Potential ◽  
External Carbon Source ◽  
Batch Tests ◽  
Sewage Plant ◽  
The Mean ◽  
Lower Temperature

The aim of this study is to investigate the denitrification efficiency enhancement and to evaluate the denitrification potential at the condition of lower temperature. Three identical biofilter were operated in parallel at batch tests. Results showed that the denitrification potential can be substantially increased by addition of ethanol and hydrolysate of sludge as external carbon sources compared with raw sewage. The mean denitrification rates of ethanol and hydrolysate reached up to 0.058 and 0.08 mgN/(g MLVSS•h), respectively, while that of raw sewage was only 0.041 mgN/(g MLVSS•h). The denitrification potential increased respectively from 0.76 to 1.54 and 5.3 mg NO3-N/L owing to ethanol and hydrolysate addition. By comparison, hydrolysate of sludge was found to be the better carbon source for denitrification considering strengthening denitrification performance and price. This study provides evidence for external carbon sources choice of sewage plant and surplus sludge reutilization.

Biological Filters for Post-Denitrification

1993 ◽  
Vol 27 (5-6) ◽  
pp. 369-379 ◽  
Author(s):  
Svend-Erik Jepsen ◽  
Jes la Cour Jansen
Keyword(s):  
Carbon Source ◽  
Wastewater Treatment Plants ◽  
Removal Rate ◽  
Head Loss ◽  
Slow Increase ◽  
Loading Rates ◽  
Carrier Material ◽  
External Carbon Source ◽  
Removal Capacity ◽  
Biological Filters

Nitrifying wastewater treatment plants exist in many European countries. These plants can be extended for Total-Nitrogen removal by a post-denitrification stage using an external carbon source. A compact solution for this process is submerged biological filters. Two pilot plants have been used as post-denitrification reactors, a down-flow filter with expanded slate as carrier material (Biocarbone) and an up-flow filter with polystyrene pellets as carrier material (Biostyr). Nitrified wastewater was treated to a stable effluent quality from both pilot plants to below the Danish effluent standard which is 8 mg Tot-N/l. The pilot plants have been operated at different loading rates with acetate as external carbon source. Stable removal with effluent nitrate less than 5 mg NO3-N/l was obtained for loading rates up to more than 4 kg NO3-N/m3 d at 10-17°C. The removal capacity of the pilot plants has been shown to be independent of time from last backwash. The removal rate over different sections of the filters does not change within one operation cycle. The backwash removes the excess biomass and particles which cause the head loss, but the removal capacity remains in the filter. The head loss development in the two systems is quite different. In the Biostyr system, the head loss raises close to linear with time (load), while the Biocarbone shows slow increase in head loss with time until the surface is clogged by incoming particles and biomass growth. When this occurs, the nitrogen bubbles, which are produced in the lower part of the filter, are trapped just below the top layer. The void volume of the filter is occupied by nitrogen gas and the head loss increases very fast to the terminal head loss. This investigation has shown that both kinds of submerged filters are capable to serve as post-denitrification reactors to remove nitrate to the most stringent effluent standards.

Treatment of Mariculture Wastewater Using Constructed Wetlands under Antibiotic Interference

2014 ◽  
Vol 522-524 ◽  
pp. 849-853 ◽  
Author(s):  
Qi Shuo Wang ◽  
Ji Guang Li ◽  
Chun Jun Wang ◽  
Xiu Ping Cai ◽  
Hui Sun ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Removal Rate ◽  
Drug Resistant ◽  
Vertical Flow ◽  
Toc Removal ◽  
N Removal ◽  
Wetland System ◽  
Aquaculture Wastewater ◽  
Upper Level

Wetland wastewater treatment commonly used in farming, but aquaculture wastewater often contains large amounts of antibiotics, making the wetland system there is uncertainty on the removal of contaminants. To this end, this paper four antibiotics (Ampicillin, Oxytetracycline, Bacitracin, Colistin sulfate) composite vertical flow constructed wetland wastewater treatment on the effects of mariculture. The results showed that for the next four kinds of antibiotics interfere IVCW with TOCNH3-NNO3--N removal rate decreased; But after some time, TE for TOC removal and CS for NO3--N removal was without interference. In addition, wetland microbial resistance to antibiotics will be gradually formed, the lower the formation of drug-resistant and high resistant faster than the upper level, and prolonged use of broad-spectrum antibiotics are more prone to tolerance.

Reversing Clogging in Vertical-Flow Constructed Wetlands by Backwashing Treatment

2010 ◽  
Vol 129-131 ◽  
pp. 1064-1068
Author(s):  
Fei Ma ◽  
Li Jiang ◽  
Ting Zeng
Keyword(s):  
Waste Water ◽  
Hydraulic Conductivity ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Removal Rate ◽  
Pollutant Removal ◽  
Vertical Flow ◽  
Vertical Flow Constructed Wetlands ◽  
The World ◽  
Design Guidance

More and more constructed wetland CW) were used to treat waste water in the world for its advantage on cheaper and efficiency. CW would clog for improper design or imperfect management, so application for it was limited. The purpose of this paper is that using backwashing method resolve filter media clogging problem which is an intractable matter in constructed wetlands project. The effects of the backwashing treatment on pollutant removal, as well as the influence on characteristics of hydraulics of wetlands, were studied. The experimental results indicate that CW hydraulic conductivity, hydraulic resistance time and removal rate of COD increased after backwashing. This paper confirmed that backwashing method can reverse clogging in vertical-flow constructed wetlands, and provided design guidance for applying backwashing method to treat clogging vertical-flow constructed wetlands.

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