scholarly journals Understanding the Spatial Heterogeneity of CO2 and CH4 Fluxes from an Urban Shallow Lake: Correlations with Environmental Factors

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Zhenhua Zhao ◽  
Dan Zhang ◽  
Wenmei Shi ◽  
Xiaohong Ruan ◽  
Jie Sun
Keyword(s):  
Environmental Factors ◽  
Sampling Site ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Oxidation Reduction ◽  
Air Interface ◽  
Oxidation Reduction Potential ◽  
Heavy Pollution ◽  
High Concentrations

The spatial variability of carbon dioxide (CO2) and methane (CH4) fluxes across water-air interface in Xuanwu Lake was investigated in two seasons. Due to anthropogenic disturbances, the environmental factors and the fluxes of CO2 and CH4 in lake showed obvious spatial and seasonal variability; their average fluxes in summer are significantly higher than those in autumn. The fluxes in heavy pollution sites with high concentrations of nitrogen and phosphorus nutrient in summer were 3.9 times (142.14 : 36.07 mg·m−2·h−1) for CO2 and 22.3 times for CH4 (6.46 : 0.29) higher than those in little pollution sites. In autumn, they were 12.3 times and 7.1 times higher, respectively. Anthropogenic disturbance and heavy pollution increased their fluxes, but aquatic plants reduced the emission of CO2. Except the sampling site with flourishing lotus, most of sampling sites without aquatic plant are the emission source of CO2 and CH4. The correlation analysis, multiple stepwise regression, and redundancy analysis showed the key environmental factors for CO2 including temperature (T), pH, chemical oxygen demand (CODMn) in water, organic matter (OM), total nitrogen, and ammonia nitrogen in water and sediment. As for CH4, the key environmental factors include turbidity, oxidation-reduction potential, dissolved oxygen, CODMn, and T in water and OM and N-NH4+ in sediment.

scholarly journals Water Quality and Microbial Community Changes in an Urban River after Micro-Nano Bubble Technology in Situ Treatment

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 66 ◽  
Author(s):  
Yifei Wu ◽  
Hui Lin ◽  
Weizhao Yin ◽  
Sicheng Shao ◽  
Sihao Lv ◽  
...  
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Dominant Bacteria

Currently, black-odor river has received great attention in China. In this study, the micro-nano bubble technology (MBT) was used to mitigate the water pollution rapidly and continuously by increasing the concentration of dissolved oxygen (DO) in water. During treatment, the concentration of DO increased from 0.60 mg/L to over 5.00 mg/L, and the oxidation reduction potential (ORP) also changed from a negative value to over 100.00 mV after only five days aeration. High throughput pyrosequencing technology was employed to identify the microbial community structure. At genus level, the dominant bacteria were anaerobic and nutrient-loving microbes (e.g., Arcobacter sp., Azonexus sp., and Citrobacter sp.) before, and the relative abundances of aerobic and functional microbes (e.g., Perlucidibaca sp., Pseudarcicella sp., Rhodoluna sp., and Sediminibacterium sp.) were increased after treatment. Meanwhile, the water quality was significantly improved with about 50% removal ratios of chemical oxygen demand (CODCr) and ammonia nitrogen (NH4+-N). Canonical correspondence analysis (CCA) results showed that microbial community structure shaped by COD, DO, NH4+-N, and TP, CCA1 and CCA2 explained 41.94% and 24.56% of total variances, respectively. Overall, the MBT could improve the water quality of urban black-odor river by raising the DO and activate the aerobic microbes.

scholarly journals Dynamic control of nutrient-removal from industrial wastewater in a sequencing batch reactor, using common and low-cost online sensors

2015 ◽  
Vol 73 (4) ◽  
pp. 740-745 ◽  
Author(s):  
Jan Dries
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Industrial Wastewater ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Low Cost ◽  
Dynamic Control ◽  
Oxygen Demand ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

On-line control of the biological treatment process is an innovative tool to cope with variable concentrations of chemical oxygen demand and nutrients in industrial wastewater. In the present study we implemented a simple dynamic control strategy for nutrient-removal in a sequencing batch reactor (SBR) treating variable tank truck cleaning wastewater. The control system was based on derived signals from two low-cost and robust sensors that are very common in activated sludge plants, i.e. oxidation reduction potential (ORP) and dissolved oxygen. The amount of wastewater fed during anoxic filling phases, and the number of filling phases in the SBR cycle, were determined by the appearance of the ‘nitrate knee’ in the profile of the ORP. The phase length of the subsequent aerobic phases was controlled by the oxygen uptake rate measured online in the reactor. As a result, the sludge loading rate (F/M ratio), the volume exchange rate and the SBR cycle length adapted dynamically to the activity of the activated sludge and the actual characteristics of the wastewater, without affecting the final effluent quality.

Performance and metabolic aspects of a novel enhanced biological phosphorus removal system with intermittent feeding and alternate aeration

2013 ◽  
Vol 69 (8) ◽  
pp. 1612-1619 ◽  
Author(s):  
Paraschos Melidis ◽  
Anastasios G. Kapagiannidis ◽  
Spyridon Ntougias ◽  
Konstantina Davididou ◽  
Alexander Aivasidis
Keyword(s):  
Phosphorus Removal ◽  
Feeding Strategy ◽  
Oxygen Demand ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Intermittent Feeding ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
On Line ◽  
Biological Phosphorus

A novel enhanced biological phosphorus removal (EBPR) system, which combined the intermittent feeding design with an anaerobic selector, was examined using on-line oxidation reduction potential (ORP), nitrate and ammonium probes. Two experimental periods were investigated: the aerobic and anoxic phases were set at 40 and 20 minutes respectively for period I, and set at 30 and 30 minutes for period II. Chemical oxygen demand (COD), biochemical oxygen demand (BOD5) and P removal were measured as high as 87%, 96% and 93% respectively, while total Kjeldahl nitrogen (TKN) and NH4+ removal averaged 85% and 91%. Two specific denitrification rates (SDNRs), which corresponded to the consumption of the readily biodegradable and slowly biodegradable COD, were determined. SDNR-1 and SDNR-2 during period I were 0.235 and 0.059 g N g−1 volatile suspended solids (VSS) d−1 respectively, while the respective rates during period II were 0.105 and 0.042 g N g−1 VSS d−1. The specific nitrate formation and ammonium oxidizing rates were 0.076 and 0.064 g N g−1 VSS d−1 for period I and 0.065 and 0.081 g N g−1 VSS d−1 for period II respectively. The specific P release rates were 2.79 and 4.02 mg P g−1 VSS h−1 during period I and II, while the respective anoxic/aerobic uptake rates were 0.42 and 0.55 mg P g−1 VSS h−1. This is the first report on an EBPR scheme using the intermittent feeding strategy.

Microbial Biomass and Enzyme Activities in Chromium and Lead-Contaminated Sediments

2013 ◽  
Vol 798-799 ◽  
pp. 1139-1143
Author(s):  
Chao Wang ◽  
Shuai Cheng ◽  
Pei Fang Wang ◽  
Yan Yan Ma
Keyword(s):  
Heavy Metals ◽  
Microbial Biomass ◽  
Enzyme Activities ◽  
Chemical Properties ◽  
Nitrogen And Phosphorus ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Organic Carbon Oxidation ◽  
The Relationship ◽  
Cr Contamination

The relationship between microbial biomass and enzyme activities under heavy metal pollution had attracted much attention in ecology. The experimental sediment samples were supplemented with Pb and Cr and incubated at room temperature for a month. Microbial properties such as microbial biomass, urease, catalase and cellulase activities, together with several chemical properties such as pH, total organic carbon , oxidation-reduction potential, total nitrogen and phosphorus were measured to evaluate changes in sediment qualities. Our results demonstrate that heavy metals would inhibit sediment microbe biomass and enzyme activities. Such decreases in sediments microbial biomass and enzyme activities by Pb and Cr contamination may help to evaluate heavy metals contaminated soil ecologies.

The ecological filter system for treatment of decentralized wastewater

2016 ◽  
Vol 74 (7) ◽  
pp. 1553-1560
Author(s):  
Kun Zhong ◽  
Yi-yong Luo ◽  
Zheng-song Wu ◽  
Qiang He ◽  
Xue-bin Hu ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Organic Pollutants ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Treatment Technology ◽  
Removal Rates ◽  
Carbon Nitrogen Ratio ◽  
Ecological Filter ◽  
Aerated Filter

A vertical flow constructed wetland was combined with a biological aerated filter to develop an ecological filter, and to obtain the optimal operating parameters: The hydraulic loading was 1.55 m3/(m2·d), carbon–nitrogen ratio was 10, and gas–water ratio was 6. The experimental results demonstrated considerable removal efficiency of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) in wastewater by the ecological filter, with average removal rates of 83.79%, 93.10%, 52.90%, and 79.07%, respectively. Concentration of NH4+-N after treatment met the level-A discharge standard of GB18918-2002. Compared with non-plant filter, the ecological filter improved average removal efficiency of COD, NH4+-N, TN, and TP by 13.03%, 25.30%, 14.80%, and 2.32%, respectively: thus, plants significantly contribute to the removal of organic pollutants and nitrogen. Through microporous aeration and O2 secretion of plants, the ecological filter formed an aerobic–anaerobic–aerobic alternating environment; thus aerobic and anaerobic microbes were active and effectively removed organic pollutants. Meanwhile, nitrogen and phosphorus were directly assimilated by plants and as nutrients of microorganisms. Meanwhile, pollutants were removed through nitrification, denitrification, filtration, adsorption, and interception by the filler. High removal rates of pollutants on the ecological filter proved that it is an effective wastewater-treatment technology for decentralized wastewater of mountainous towns.

Experimental considerations on monitoring ORP, pH, conductivity and dissolved oxygen in nitrogen and phosphorus biological removal processes

2001 ◽  
Vol 43 (11) ◽  
pp. 197-204 ◽  
Author(s):  
A. Spagni ◽  
J. Buday ◽  
P. Ratini ◽  
G. Bortone
Keyword(s):  
Dissolved Oxygen ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Effective Control ◽  
Monitoring And Control ◽  
Nitrogen And Phosphorus ◽  
Ph Variation ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Removal Processes

An experimental study on monitoring Oxidation Reduction Potential (ORP), pH, Conductivity and Dissolved Oxygen (DO) in an Enhanced Biological Nutrient Removal process has been carried out. In the anaerobic phase, while ORP and conductivity were not reliable in monitoring simultaneously denitrification and P-release, pH showed the best performances. A significant relationship between P-released and pH variation was found. During the aerobic phase both ORP and pH were able to monitor successfully the nitrification, even though pH was much more reliable. pH can be also used for monitoring and control enhanced P-uptake. It has been concluded that, for a reliable and effective control of biological N and P removal processes a more sophisticated control system seems to be necessary.

Effects of chemical oxygen demand (COD)/N ratios on pollutants removal in the subsurface wastewater infiltration systems with/without intermittent aeration

2016 ◽  
Vol 73 (11) ◽  
pp. 2662-2669 ◽  
Author(s):  
Siyu Song ◽  
Jing Pan ◽  
Shiwei Wu ◽  
Yijing Guo ◽  
Jingxiao Yu ◽  
...  
Keyword(s):  
Chemical Oxygen Demand ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Oxygen Deficiency ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Intermittent Aeration ◽  
Oxidation Reduction ◽  
The Matrix ◽  
Pollutants Removal

The matrix oxidation reduction potential level, organic pollutants and nitrogen removal performances of eight subsurface wastewater infiltration systems (SWISs) (four with intermittent aeration, four without intermittent aeration) fed with influent chemical oxygen demand (COD)/N ratio of 3, 6, 12 and 18 were investigated. Nitrification of non-aerated SWISs was poor due to oxygen deficiency while higher COD/N ratios further led to lower COD and nitrogen removal rate. Intermittent aeration achieved almost complete nitrification, which successfully created aerobic conditions in the depth of 50 cm and did not change anoxic or anaerobic conditions in the depth of 80 and 110 cm. The sufficient carbon source in high COD/N ratio influent greatly promoted denitrification in SWISs with intermittent aeration. High average removal rates of COD (95.68%), ammonia nitrogen (NH4+-N) (99.32%) and total nitrogen (TN) (89.65%) were obtained with influent COD/N ratio of 12 in aerated SWISs. The results suggest that intermittent aeration was a reliable option to achieve high nitrogen removal in SWISs, especially with high COD/N ratio wastewater.

scholarly journals Bacterial community shift and effects of the inclusion of a mixed psychrotrophic bacteria strain for sewage treatment in constructed wetland in winter seasons

2021 ◽  
Author(s):  
xiaoyan xu ◽  
Jie Jiang ◽  
Zhinan Guo ◽  
Lianglun Sun ◽  
Meizhen Tang
Keyword(s):  
Low Temperature ◽  
Constructed Wetlands ◽  
High Throughput Sequencing ◽  
Sewage Treatment ◽  
High Capacity ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Degradation Kinetic ◽  
Psychrotrophic Bacteria

Abstract The mechanism of wastewater treatment based on psychrophilic strains to improve the denitrification efficiency of constructed wetlands at low temperatures has already become a new hotspot. In this study, three mixed psychrophilic strains (Psychrobacter TM-1, Sphingobacterium TM-2 and Pseudomonas TM-3) with high capacity of denitrification were added into a vertical-flow constructed wetlands (CWs), and the effect of the mixed strains on CWs sewage treatment was evaluated. The removal efficiency of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN) and total phosphorus (TP) was quantified to establish the degradation kinetic model and determine the best dosage of the mixed strains. The effect mechanism of the mixed strains on indigenous microbial community and the change of sewage treatment performance in low temperature constructed wetlands was clarified by high-throughput sequencing technology. The results showed that the mixed strains can effectively remove the organic pollutants (nitrogen and phosphorus) and the optimum dosage of the mixed strain was 2.5%,with average removal rates of 1.52, 2.12, 2.07 and 1.29 times than those of the control. Meanwhile, the dominant strains in the CWs were Proteobacteria (31.23–44.34%), Chloroflexi (12.04–19.05%), Actinobacteria (10.6-20.62%), Acidobacteria (8.23–11.65%), Firmicutes (2.23–15.95%) and Bacteroidetes (4.01–18.9%). These findings provide a basis for the removal of pollutants in constructed wetlands at low temperature.

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