scholarly journals Correcting a major error in assessing organic carbon pollution in natural waters

2021 ◽  
Vol 7 (16) ◽  
pp. eabc7318
Author(s):  
Nianzhi Jiao ◽  
Jihua Liu ◽  
Bethanie Edwards ◽  
Zongqing Lv ◽  
Ruanhong Cai ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Natural Waters ◽  
Carbon Sink ◽  
Scientific Information ◽  
Experimental Studies ◽  
Oxygen Demand ◽  
Organic Pollution ◽  
Oxygen Depletion ◽  
Aquatic Environments ◽  
Forested Areas

Microbial degradation of dissolved organic carbon (DOC) in aquatic environments can cause oxygen depletion, water acidification, and CO2 emissions. These problems are caused by labile DOC (LDOC) and not refractory DOC (RDOC) that resists degradation and is thus a carbon sink. For nearly a century, chemical oxygen demand (COD) has been widely used for assessment of organic pollution in aquatic systems. Here, we show through a multicountry survey and experimental studies that COD is not an appropriate proxy of microbial degradability of organic matter because it oxidizes both LDOC and RDOC, and the latter contributes up to 90% of DOC in high-latitude forested areas. Hence, COD measurements do not provide appropriate scientific information on organic pollution in natural waters and can mislead environmental policies. We propose the replacement of the COD method with an optode-based biological oxygen demand method to accurately and efficiently assess organic pollution in natural aquatic environments.

scholarly journals Impact of Global Warming on Dissolved Oxygen and BOD Assimilative Capacity of the World’s Rivers: Modeling Analysis

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2408
Author(s):  
Steven C. Chapra ◽  
Luis A. Camacho ◽  
Graham B. McBride
Keyword(s):  
Dissolved Oxygen ◽  
Natural Waters ◽  
Cold Water ◽  
Oxygen Demand ◽  
Oxygen Depletion ◽  
Assimilative Capacity ◽  
Mountainous Regions ◽  
Modeling Analysis ◽  
Lower Oxygen ◽  
The Impact

For rivers and streams, the impact of rising water temperature on biochemical oxygen demand (BOD) assimilative capacity depends on the interplay of two independent factors: the waterbody’s dissolved oxygen (DO) saturation and its self-purification rate (i.e., the balance between BOD oxidation and reaeration). Although both processes increase with rising water temperatures, oxygen depletion due to BOD oxidation increases faster than reaeration. The net result is that rising temperatures will decrease the ability of the world’s natural waters to assimilate oxygen-demanding wastes beyond the damage due to reduced saturation alone. This effect should be worse for nitrogenous BOD than for carbonaceous BOD because of the former’s higher sensitivity to rising water temperatures. Focusing on streams and rivers, the classic Streeter–Phelps model was used to determine the magnitude of the maximum or “critical” DO deficit that can be calculated analytically as a function of the mixing-point BOD concentration, DO saturation, and the self-purification rate. The results indicate that high-velocity streams will be the most sensitive to rising temperatures. This is significant because such systems typically occur in mountainous regions where they are also subject to lower oxygen saturation due to decreased oxygen partial pressure. Further, they are dominated by salmonids and other cold-water fish that require higher oxygen levels than warm-water species. Due to their high reaeration rates, such systems typically exhibit high self-purification constants and consequently have higher assimilation capacities than slower moving lowland rivers. For slow-moving rivers, the total sustainable mixing-point concentration for CBOD is primarily dictated by saturation reductions. For faster flowing streams, the sensitivity of the total sustainable load is more equally dependent on temperature-induced reductions in both saturation and self-purification.

scholarly journals Excessive greenhouse gas emissions from wastewater treatment plants by using the chemical oxygen demand standard

2021 ◽  
Author(s):  
Zongqing Lv ◽  
Xiaoyu Shan ◽  
Xilin Xiao ◽  
Ruanhong Cai ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Chemical Oxygen Demand ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Carbon Sink ◽  
Oxygen Demand ◽  
Organic Pollution ◽  
Municipal Wastewater Treatment ◽  
Recalcitrant Organic Matter

AbstractChemical oxygen demand (COD) is widely used as an organic pollution indicator in wastewater treatment plants. Large amounts of organic matter are removed during treatment processes to meet environmental standards, and consequently, substantial greenhouse gases (GHGs) such as methane (CH4) are released. However, the COD indicator covers a great amount of refractory organic matter that is not a pollutant and could be a potential carbon sink. Here, we collected and analysed COD data from 86 worldwide municipal wastewater treatment plants (WWTPs) and applied a model published by the Intergovernmental Panel on Climate Change to estimate the emission of CH4 due to recalcitrant organic compound processing in China’s municipal wastewater treatment systems Our results showed that the average contribution of refractory COD to total COD removal was 55% in 86 WWTPs. The amount of CH4 released from the treatment of recalcitrant organic matter in 2018 could have been as high as 38.22 million tons of carbon dioxide equivalent, which amounts to the annual carbon sequestered by China’s wetlands. This suggests that the use of COD as an indicator for organic pollution is undue and needs to be revised to reduce the emission of GHG. In fact, leaving nontoxic recalcitrant organic matter in the wastewater may create a significant carbon sink and will save energy during the treatment process, aiming at carbon neutrality in the wastewater treatment industry.

scholarly journals Partial coupling and differential regulation of biologically and photochemically labile dissolved organic carbon across boreal aquatic networks

2014 ◽  
Vol 11 (20) ◽  
pp. 5969-5985 ◽  
Author(s):  
J.-F. Lapierre ◽  
P. A. del Giorgio
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Large Scale ◽  
Natural Waters ◽  
Boreal Lakes ◽  
Aquatic Environments ◽  
Photochemical Degradation ◽  
Landscape Gradients ◽  
Partial Coupling ◽  
Internal Production

Abstract. Despite the rapidly increasing volume of research on the biological and photochemical degradation of DOC (dissolved organic carbon) in aquatic environments, little is known of the large-scale patterns in biologically and photochemically degradable DOC (BDOC and PDOC, respectively) in continental watersheds, and on the links that exist between these two key properties that greatly influence the flow of carbon from continents to oceans. Here we explored the patterns in the concentrations and proportions of BDOC and PDOC across hundreds of boreal lakes, rivers and wetlands spanning a large range of system trophic status and terrestrial influence, and compared the drivers of these two reactive pools of DOC at the landscape level. Using standardized incubations of natural waters, we found that the concentrations of BDOC and PDOC covaried across all systems studied but were nevertheless related to different pools of dissolved organic matter (DOM; identified by fluorescence analyses) in ambient waters. Concentrations of nutrients and protein-like fluorescent DOM (FDOM) explained nearly half of the variation in BDOC, whereas PDOC was exclusively predicted by DOM optical properties, consistent with the photochemical degradability of specific FDOM pools that we experimentally determined. The concentrations of colored DOM (CDOM), which we use here as a proxy of terrestrial influence, almost entirely accounted for the observed relationship between FDOM and the concentrations of both BDOC and PDOC. The concentrations of CDOM and of the putative biolabile fluorescence component shifted from complete decoupling in clear-water environments to strong coupling in darker streams and wetlands. This suggests a baseline autochthonous BDOC pool fueled by internal production that is gradually overwhelmed by land-derived BDOC as terrestrial influence increases across landscape gradients. The importance of land as a major source of both biologically and photochemically degradable DOC for continental watersheds resulted in a partial coupling of those carbon pools in natural freshwaters, despite fundamental contrasts in terms of their composition and regulation.

scholarly journals The Correlation Analysis of TOC and CODCr in Urban Sewage Treatment

2019 ◽  
Vol 136 ◽  
pp. 06010 ◽  
Author(s):  
Xi Tian ◽  
Chunling Zhao ◽  
Xiaona Ji ◽  
Tiezhu Feng ◽  
Ying Liu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Correlation Coefficient ◽  
Water Samples ◽  
Municipal Wastewater ◽  
Sewage Treatment ◽  
Oxygen Demand ◽  
Organic Pollution ◽  
Urban Sewage ◽  
Treated Effluent

Total organic carbon (TOC) and chemical oxygen demand (CODCr) are indicators of the degree of organic pollution in water. At present, CODCr is mainly used as an evaluation index in China, and the detection method of CODCr is more complicated and time-consuming than TOC. In this paper, it uses the Micro-Pressure Inner-Loop Bioreactor (MPR) to treat urban sewage, studies the treatment effect of MPR on organic pollutants, and further analyzes the correlation between TOC and CODCr. TOC and CODCr of municipal wastewater and MPR treated effluent were measured by total organic carbon analyzer and dichromate method respectively, and the degree of organic pollution of water samples was analyzed. The results showed that the average removal rates of TOC and CODCr in municipal wastewater were 83.54% and 90.81%, respectively. The theoretical correlation coefficient between TOC and CODCr in experimental raw water was only 0.7322. After MPR treatment, the correlation coefficient increased to 0.9534. For water samples with fixed contaminants and stable contents, TOC can be used to calculate water CODCr by linear fitting relationship.

Hydro-geochemical properties with respect to landuse in the southernmost river of Kerala

2018 ◽  
Vol 6 (1) ◽  
Author(s):  
Badusha M. ◽  
Santhosh S
Keyword(s):  
Organic Carbon ◽  
Drainage Basin ◽  
Anthropogenic Activities ◽  
Oxygen Demand ◽  
Ion Concentration ◽  
Total Hardness ◽  
Hydrogen Ion Concentration ◽  
Geochemical Properties ◽  
Quality Of Water

The hydro geochemical features of Neyyar River for a period of one year from May 2015 to April 2016 were analyzed. Six sampling sites were fixed considering physiography and present landuse pattern of the river basin. The residents in the drainage basin are primarily responsible for framing a better landuse and thereby maintain a good water and sediment regime. Geospatial pattern of the present landuse of the study area indicated that the sustainability of this river ecosystem is in danger due to unscientific landuse practices, which is reflected in the river quality as well. The parameters such as hydrogen ion concentration, electrical conductivity, chloride, Biological Oxygen Demand, total hardness and sulphate of river water and Organic Carbon of river bed sediments were analyzed in this study. The overall analysis shows that the highland areas are characterized by better quality of water together with low organic carbon, which is mainly due to better landuse and minimal reclamation. The midland and lowland areas are characterized by poor quality of water with high organic carbon, which is due to high anthropogenic activities and maximum pollutants associated with the region together with the alteration in landuse from a traditional eco-friendly pattern to a severely polluted current pattern.

Investigation of the Contribution of Natural Organic Runoff to Dissolved Oxygen Depletion in the Red Deer River

1979 ◽  
Vol 14 (1) ◽  
pp. 71-88
Author(s):  
S.E. Penttinen ◽  
P.H. Bouthillier ◽  
S.E. Hrudey
Keyword(s):  
Dissolved Oxygen ◽  
Red Deer ◽  
Stream Water ◽  
Oxygen Demand ◽  
Oxygen Depletion ◽  
Experimental Program ◽  
Nitrogen Budgets ◽  
Carbon And Nitrogen ◽  
Tributary Stream ◽  
Small Tributary

Abstract Studies on the chronic low dissolved oxygen problems encountered under winter ice in the Red Deer River have generally been unable to account for dissolved oxygen depletion in terms of known manmade inputs. An experimental program was developed to assess the possible nature and approximate bounds of oxygen demand due to natural organic runoff carried to the Red Deer River by a small tributary stream, the Blindman River. The study employed an electrolytic respirometer on stream water samples subjected to prior concentration by vacuum evaporation. Evaluation of carbon and nitrogen budgets in conjunction with the measured oxygen demand indicate that biochemical oxygen demand is originating with natural organic runoff in tributaries of the Red Deer River. The results provide a basis for estimation of the possible contribution to the observed oxygen demand in the Red Deer River originating from natural organic runoff.

A simple test for monitoring biodegradable industrial pollution in a receiving stream

1999 ◽  
Vol 39 (10-11) ◽  
pp. 221-224 ◽  
Author(s):  
Jana Zagorc-Končan ◽  
J. Šömen
Keyword(s):  
Hazard Assessment ◽  
Industrial Pollution ◽  
Self Regulation ◽  
Oxygen Demand ◽  
Organic Pollution ◽  
Organic Substances ◽  
Simple Test ◽  
Industrial Pollutants ◽  
Model Substances ◽  
Receiving Stream

Microbial purification capacity is an important factor in natural self-regulation in water. Evaluating the fate of biodegradable organic pollution downstream from the discharge seems an appropriate way to follow the effect of pollution and its hazard assessment, which dictates the needed sanitation measures. We suggest a simple test for such monitoring. A modification of the additional oxygen demand test, standardised in Ausgewählte Methoden der Wasseruntersuchung, was applied in two river case studies. The additional oxygen demand is a measure of the capability and rate of biodegradation of known organic substance as well as of the amount and activity of heterotrophic organisms in the river. The original test using peptone and glucose as additional feedings of BOD samples was modified by the use of other organic biodegradable model substances characteristic for individual industrial pollutants. The test was found to be an excellent indicator of adapted microorganisms, which are essential for the biodegradation of the appointed organic substances downstream of their discharge into the receiving stream.

scholarly journals Impact of aquaculture on distribution of dissolved organic matter in coastal Jeju Island, Korea, based on absorption and fluorescence spectroscopy

2021 ◽  
Author(s):  
Jeonghyun Kim ◽  
Yeseul Kim ◽  
Sung Eun Park ◽  
Tae-Hoon Kim ◽  
Bong-Guk Kim ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Fluorescence Spectroscopy ◽  
Dissolved Organic Matter ◽  
Coastal Water ◽  
Coastal Region ◽  
Principal Component ◽  
Distribution Patterns ◽  
Organic Pollution ◽  
Jeju Island

AbstractIn Jeju Island, multiple land-based aquafarms were fully operational along most coastal region. However, the effect of effluent on distribution and behaviours of dissolved organic matter (DOM) in the coastal water are still unknown. To decipher characteristics of organic pollution, we compared physicochemical parameters with spectral optical properties near the coastal aquafarms in Jeju Island. Absorption spectra were measured to calculate the absorption coefficient, spectral slope coefficient, and specific UV absorbance. Fluorescent DOM was analysed using fluorescence spectroscopy coupled with parallel factor analysis. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were measured using high-temperature catalytic oxidation. The DOC concentration near the discharge outlet was twice higher than that in natural groundwater, and the TDN concentration exponentially increased close to the outlet. These distribution patterns indicate that aquafarms are a significant source of DOM. Herein, principal component analysis was applied to categorise the DOM origins. There were two distinct groups, namely, aquaculture activity for TDN with humic-like and high molecular weights DOM (PC1: 48.1%) and natural biological activity in the coastal water for DOC enrichment and protein-like DOM (PC2: 18.8%). We conclude that the aquafarms significantly discharge organic nitrogen pollutants and provoke in situ production of organic carbon. Furthermore, these findings indicate the potential of optical techniques for the efficient monitoring of anthropogenic organic pollutants from aquafarms worldwide.

Relationship between Pseudomonas aeruginosa and Bacterial Indicators in Polluted Natural Waters

1991 ◽  
Vol 24 (2) ◽  
pp. 121-124 ◽  
Author(s):  
A. de Vicente ◽  
J. C. Codina ◽  
P. Romero
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Natural Waters ◽  
Pollution Index ◽  
Close Correlation ◽  
Aquatic Environments ◽  
Faecal Coliforms ◽  
Faecal Pollution ◽  
The Relationship ◽  
Faecal Indicators ◽  
Faecal Streptococci

The relationship between Pseudomonas aeruginosa and the faecal pollution index (total coliforms, faecal coliforms and faecal streptococci) in natural waters was established. Water samples were collected from several aquatic environments in Málaga (Spain). P. aeruginosa counts and isolation frequencies were clearly associated with the degree of faecal pollution of the studied water. The results confirmed that domestic sewage was the major source of P. aeruginosa in river and seawater, being isolated from sewage at concentrations about 105 cfu/100 ml. There was a close correlation between the P. aeruginosa concentration and the densities of the three faecal indicators in both river and marine waters. A significant correlation was not observed in waters with little faecal pollution because P. aeruginosa was only occasionally isolated from these waters and at very low densities. P. aeruginosa concentrations in sewage and polluted natural waters were generally 3-4 log lower than the TC densities and 2 log lower than FC and FS concentrations. TC, FC and FS could be considered adequate indicators of the presence and densities of P. aeruginosa in natural waters, especially TC in freshwaters and FS in seawater respectively, as these parameters showed the best correlations and the most parallel inactivation processes with P. aeruginosa in each environment.

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