Organic load control in drinking water – Second part

Objectives that we will develop in this article:

Objectives that we will develop in this article:

  1. Improved efficiency in the addition of chemicals in the coagulation-flocculation process
  2. Detection in time of the saturation of the activated carbon filters.
  3. Decrease in energy consumption in the control of UV disinfection and increase the durability of the lamps.
  4. Water storage: ensuring the quality of drinking water by continuously measuring the
    organic contaminants prior to distribution


Let’s remember where we can measure the organic load in a drinking water plant


The water intake was dealt with in the first part.



Coagulation / flocculation followed by sedimentation / filtration is a process to remove suspended solids of an organic and inorganic nature from drinking water.


  • Monitoring of the effective removal of natural organic matter (NOM) in the coagulation and sedimentation process
  • Improved process monitoring, improving the efficiency and effectiveness of chemical addition and energy consumption.

Microorganisms + NOM + disinfectant ———> Destroyed microorganisms + disinfection by-products (DPB), associated with various types of cancer. Limited in RD 140/2003.

The following graph shows the formation of the main and most elemental of these by-products, chloroform, depending on the chlorine applied and contact time, in a given water




  • Monitoring of the effectiveness of the process in activated carbon filtration allowing to improve the prognosis in the extent of filter saturation, which minimizes unexpected downtime.
  • Measurement before and after the Active Carbon filter.

Tendency to decrease the difference between input and output.


Correct levels of SAC 254nm at the outlet of the activated carbon filter



Verify and optimize proper UV disinfection.

  • Process control, improved by monitoring the effectiveness and efficiency of UV disinfection.
  • UV light with wavelength <280nm destroys the DNA of microorganisms.
  • The efficiency of disinfection is given by the formula:
    UV intensity (expressed as energy per unit area) x resistance time.
    The proper UV dosage for each application must take into account water quality, arc tube aging, industry specifications, and microbiological standards.
  • Decrease in energy consumption in the control of UV disinfection and increase the durability of the lamps




  • Ensures the quality of drinking water by continuously measuring organic contaminants prior to distribution.
  • Controlling organic load is especially important if chlorine is used as a disinfectant, as it reacts with organic substances and forms disinfection by-products that are potentially carcinogenic, such as trihalomethanes (THM) and haloacetic acids (HAA).

A correlation with various carbon-based parameters is also possible, as long as the composition of the water pollutants remains constant.

Common correlations:

COD chemical oxygen demand
TOC: total organic carbon
BOD. Biochemical Oxygen Demand



  1. In surface water, the natural organic load can be very variable, so its detection online can be very important, to optimize its treatment and constantly ensure high water quality.
  2. Anticipation and reduction of disinfection by-products (SPD)
  3. Optimization of the consumption of flocculants and / or coagulants.
  4. Checking the operation of decanters.
  5. Status trends of activated carbon filters.
  6. In case of using UV disinfection, analyze the SAC 254, it allows to know the state of the disinfection

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