Understanding Laboratory Wastewater Tests: I Organics BOD, COD, TOC, O&G
The central point of most of these modifications is to diminish the use of highly toxic reagents or to change to others that may be more environmentally friendly. The biggest problem with several of the alternatives is their high cost and the time they require compared with the standardized method. On the other hand, fluorescence uses fluorescent chemical elements, such as Cerium (III) (Ce3+). Its fluorescence intensity changes in response to the different concentrations of organic matter in the solution. Nevertheless, it requires expensive equipment and reagents and is suitable only for slightly polluted waters (Li et al. [10, 51]. HgSO4 are added to eliminate the presence of chloride ions and silver salts to catalyze the reaction.
The regression analysis is used to predict the system’s performance and its control level as the basis for further technique and control processes for Alum dosing-enhanced primary treatment. Correlation matrix for the inlet parameters pH, TSS, COD, and BOD5 of raw sewage entering the treatment plant is developed, in addition to % TSS removal and % COD removal. For industrial samples, COD may be the only feasible test because of the presence of bacterial inhibitors or other chemical interferences, which would interfere with a BOD determination. COD testing also gives the fast measurements required in many treatment systems for informed decisions regarding process control adjustments. Many industrial and municipal laboratories find that parallel COD and BOD testing is beneficial because the COD test can be used to target a specific BOD range.
- In addition, special equipment and materials are required to perform these tests.
- Some researchers also investigated the impact of polymer addition in COD removal.
- In contrast, the patterns for non-urban areas were rather irregular with no common feature observed for the individual sewer pipe.
The BOD test Originated in the United Kingdom due to pollution in the Thames River. Legend has it that the 5-day BOD (Biological or Biochemical Oxygen Demand) test was developed in England. Sewage was dumped in a river and it took five days for it to reach the ocean, hence the five-day incubation requirement in the BOD method. Chemical Oxygen Demand (COD) analysis, on the other hand, is an accurate method that can be validated through a standard (KHP/ potassium hydrogen phthalate). COD analysis has been an easy procedure to perform since the early 1980s, with the introduction of the Hach Closed-Reflux Micro Method that uses pre-dosed reagents.
Industrial wastewater systems will more often use COD to measure the organic concentration moving through the treatment plant. In my experience, I see TOC being used much less often (rarely) than BOD or COD. Water and wastewater samples contain a diverse set of organic contaminants. While COD, BOD, and TOC each provide information about the pollution degree of water and wastewater, only TOC provides a direct measure in minutes, allowing for process control and quick decision making.
Nevertheless, currently the Total Organic Carbon (TOC) (Federation W. E., & APH Association [26] – 5310) analysis is being extensively more used than the other two [93]. BOD simulates the actual treatment plant process by measuring the organic material microorganisms can oxidize. Although COD is comparable to BOD, it actually measures chemically oxidizable matter. The COD test is not a direct substitute for the BOD test; however, a ratio usually can be correlated between the two tests.
What is the difference between BOD, COD or TOC?
Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are the traditional tools often utilised. The exception to this standard is the measurement of Total Organic Carbon (TOC), which directly measures inorganic and organic carbon. Below is a summary of each parameter, what they measure, and general strengths and weaknesses. During https://1investing.in/ the CEPT process, larger flocs are assembled and these flocs are decumbent to faster settling. The treatment efficiency also increases with the increase of floc size significantly. Different studies showed that CEPT process has effectively removed 85% and 57% of total suspended solids (TSS) and biological oxygen demand (BOD), respectively.
2 Alternatives for the analysis of TOC in water
Without BOD5 data correlated to COD data, the ratios in the table below can be used to estimate (roughly approximate, really) the relationship between COD, BOD5, and/or TOC. These ratio values are only a guide and may vary significantly from what is actually taking place at your wastewater plant. Traditional analytical tools used to determine the pollution degree of water and wastewater are lab-based tools that measure the oxygen demand required to oxidize contaminants.
Methane Emissions Analysis at Berlin Wastewater…
With the Sievers InnovOx TOC Analysers and SCWO technology, you can obtain accurate data without interference on process performance. BOD is an indicator of the fraction of organic matter that can be degraded by microorganisms, typically expressed as the amount (mg/L) of oxygen consumed over five days at 20°C. BOD includes the readily biodegradable organic carbon (carbonaceous or cBOD) and occasionally ammonia (nitrogenous or nBOD).
Is COD equal to BOD?
Monitoring BOD helps in assessing the health of water bodies, identifying pollution sources, and determining the effectiveness of wastewater treatment processes. In contrast to the fluorescence EEM that requires a number of scanning, synchronous fluorescence spectra can be obtained by only one scanning operation and most importantly, it still contains much information on the composition of organic matters. For example, Hur and Kong [11] reported a significant correlation between some selected fluorescence characteristics from synchronous fluorescence spectra and the BOD values for urban river samples affected by the effluent of a wastewater treatment plant. The main objective of the analysis was to investigate the relation between the operating parameters including COD, pH, TSS, TDS, and the removal efficiency of both COD and TSS using enhanced primary treatment technology in Gitis and Hankins (Gitis & Hankins, 2018). Different types of coagulant (FeCl3, alum, lime, and Magna-floc155), as well as different treatment capacities, were investigated.
Biochemical oxygen demand (BOD) is the amount of oxygen microorganisms require to break down organic materials. In contrast, chemical oxygen demand (COD) is the amount of oxygen relation between bod and cod required to break down the organic material via oxidation. It requires samples injection by syringe into a high temperature furnace with a platinum or cobalt catalyst.
Generally, COD is preferred to BOD for process control measurements because results are more reproducible and are available in just two hours rather than five days. By the time you have the results from a five day test, the plant conditions are no longer the same, so real time monitor and control can not be relied upon by the use of BOD. COD is a quick and easy measurement to get a snap in time picture of what is going on in the system, and with trending, long term predictions can be made and monitor and control of the process at the wastewater treatment plant can be optimized and controlled. The measurement of COD involves the chemical oxidation of organic compounds in a water sample using strong oxidizing agents, such as potassium dichromate (K₂Cr₂O₇) or potassium permanganate (KMnO₄). This oxidation process converts the organic matter into carbon dioxide and water.
CBOD is the primary driver of BOD and includes soluble, particulate, and colloidal organic carbon compounds. “Chemically enhanced primary treatment” (CEPT) is an approach to wastewater treatment. It can be utilized as a specially designed step in “biological” secondary treatment processes. The aim of this study is to create an empirical model of separation efficiency for wastewater chemically enhanced primary treatment. Although wastewater analytical tests are often separated into categories, it is important to understand that these tests are not independent of each other (Figure 1). In other words, a potential contaminant identified by one test in one category can also be identified in another test in a separate category.
At 25 °C, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. The plant uses a Hach DR/2500 Spectrophotometer, which provides lab personnel the ability to save COD and other frequently used programs for quick access. In conclusion, it is preferable to highlight the importance of TOC and the possibility of using this technique as a complementary tool to verify the results obtained by other techniques. On the other hand, only modifications in the detection systems are discussed in the analysis of TOC.
