Industrial Manufacturing

The production in the pulp and paper industry requires large amounts of water. The German Waste Water Ordinance implies that the resulting effluent has to be tested on the content of chemical oxygen demand (COD). In comparison with conventional testing methods the use of online COD analyzers offers high savings and also enables efficient water management.

Types of Water

  • Process water
  • Cooling water
  • Surface water
  • Water influent
  • Water effluent
  • Boiler feed water
  • Condensate return
  • Industrial waste water
  • Discharge control
  • Oil-in-Water
  • High salt concentrations

Reuse of Water, Effective Water Management and High Process Safety

In the steel industry water is of high importance. It is used for

  • Cooling
  • Steam generation 
  • Waste transfer
  • Dust control

As heat is used in any manufacturing process of the steel industry, the major need of water is for cooling purposes of the various facilities such as the furnace body and the actual products.

Less than 10% of this water is actually consumed. The majority is reused in recirculating systems, for example, when waste water from direct cooling is recycled back after adding make-up water. Another way to improve water efficiency is to recycle waste water and cascading water use from higher to lower quality.

Water effluents are those waters that cannot be recycled back even after treatment. Steel plants that aim for zero discharge of water effluents will treat the water to enhance its quality and use it for example in raw material dust suppression. Other plants will treat the effluents to comply emission limits in order to discharge it back to natural sources such as rivers and lakes.

Nevertheless, the monitoring of the water quality is crucial for efficient water circulation and safe plant operation.

Schematic water and sewage circulation in the pulp and paper industry

The manufacturing process of pulp and paper requires huge amounts of water. The major part of this process water is recycled within a closed water system used for

  • manufacturing - suspension, transport of pulp
  • supportive purposes - cooling water, seal water
  • cleaning purposes - sieve and felt cleaning, system cleaning

To prevent an increase in concentration and a loss of quality of the ingredients, a small amount of waste water is discharged, which is then replaced by fresh water.

During paper production about 10 m³ liters waste water is produced per 1 tonne of air dried product, during pulp production it is about 40 m³ waste water per 1 tonne pulp.

Waste waster from pulp & paper manufacturing is characterized by

  • high concentration of organic pollutants
  • high amount of fibres and particles
  • partialy toxic substances (biocides)
  • a variety of chemical additives

In the effluent of a paper mill, the monitoring of COD or TOC is of importance to determine the organic load. It is the only way to identify production losses easily and buffer problematic loads. The waste water treatment plant operators can better estimate the required cleaning performance and control it efficiently. The COD can also be determined by correlation with TOC (total organic carbon).

Additionally, the parameter TN (total bound nitrogen) is recommended for monitoring because an optimal cleaning performance needs a certain ratio of nitrogen and phosphorus. Furthermore, the waste water toxicity should be tested. Chemicals such as biocides or chlorine, which are added to avoid mold, can significantly affect the biology of a waste water treatment plant.

Need further information?

Related news for pulp and paper industry

Total Organic Carbon analysers are commonly used to measure the level of organic contamination in water. Online TOC analysers installed in refineries and petrochemical plants are located right in the middle of the process facilities.

больше...

The total organic carbon process analyzer is a measuring system for complex water applications for monitoring and optimization of industrial processes and municipal as well as industrial waste water treatment plants.

больше...

Types of Water: Water Effluent, Process Water, Industrial Waste Water

 

Parameters: TOC, TC, TNb

больше...