1. General conciusion
Water plays an important role in the industry. It can be used for cooling purposes, as a means of transportation for raw materials, as a solvent and in many other processes. There are a number of different water sources, e.g., surface water, groundwater, rainwater, tap water, seawater, etc. Not all of them can be used for each application or process since they have different properties.
In the chemical industry the share of surface water is the highest in the Flemish industry because it is being used as cooling water. Since groundwater is of a higher quality than surface water companies have used it abundantly for their processes. However, a few years ago the government started to impose taxes on the use of groundwater. This resulted in a general trend to use water more efficiently and less groundwater in particular. Different adaptations were implemented, e.g., optimizing the different processes, switching from groundwater onto surface water. One of the implications of the latter is that surface water needed to undergo different treatment steps to improve its quality before it could be used in the processes. One of the most important resuits of the efforts that were made is that although the total amount of water has increased due to a growth in industrial activity, a decrease per production unit is achieved.
The same trend is observed for the amount of wastewater discharged and the load of its pollutants. The reduction in the amount is as immediate result from the decrease in process water used. A further decrease has been obtained by as increased investigation to reuse water, e.g., in processes with lower water quality requirements, to recycle water, e.g., investing in water treatment methods, etc. Evidently the reduction in the amount of wastewater results in a reduction of the total wastewater bad for all the pollutants, e.g., COD, nitrogen, phosphor, heavy metals. The imposed taxes when the concentration of pollutants present in the wastewater exceed the standards motivate companies to take care of the concentration of the pollutants.
Of course the general trends cm be extrapolated to the individual companies. However, one bas to be aware of the differences in choice of water source due to different policies,processes, quality requirements and infrastructure problems. Since every company bas its own identity and produces sometimes very typical produets they encounter certain speeffic difficulties. Anyhow every company is striving to cut down the amount of water they use, especially groundwater, and to diminish at the same time their wastewater bad, This is often done in very typical ways.
The metallurgical industry is the second major water consumer in the Flemish industry. This industry has also made a lot of improvements in its water consumption as can be seen in its reduction in surfisce and groundwater use.
Just like the chemical industry, it is an important polluter of COD, nitrogen and floating substances, e.g., suspended solids. The concentration of nitrogen followed a general reduetion as well as the concentration of floating substances but this last has known a sudden inerease in 2002. In the case of COD, major improvements have not been made. A typical metallurgical pollutant is zine, which bas known a significant decrease but stil needs further attention since its coneentration has again exeeeded the standard.
The ehoice between sources, quantity and quality of the water is again diversified when one considers the different metallurgical sub-sectors and even more when one investigates the companies separately. Sidmar is one of the prime examples for the metallurgical industries since it has decreased its total water flow by a factor two and its pollutants with a factor ten. This was done by optimizing its installations and using surflice water wherever it was possible with or without treatment.
2. Recommendations
The chemical industry bas made a lot of efforts to reduce the amount of water they consume and to reduce its wastewater bad. A significant decrease bas been realized in the period from 1987 to 2001. It should be the task for future projects to investigate whether or not the trend is continued in the following years, and ifso, at what rate.
A more extensive research in the water use in the diflèrent cheinical seetors and more interviews with different types of companies can lead to a better insight into the difference in choice of water sources and approaches to decrease the water consumption and wastewater bad.
This can be said for the metallurgical industiy as well. Indeed it bas to be investigated if the downward trend of the consumption of water and is continued after 2001. The future evolution of zine bas to be monitored since it has known an increase above the standard the last few years. Especially the situation of COD and the floating substances bas to be closely followed. It bas to be investigated whether or not the sudden inerease in 2001 for the concentration of floating substances is a coincidence or it is a new trend. Finally, one should investigate why the total bad of COD in 2001 is again at the same level of 1992.
It should also be interesting to investigate metallurgical companies smaller than Sidmar. In this way one can find out what the choice of water sources is in smaller companies and what the improvements are that have been made to decrease water consumption and waste water bad. These results can be compared with those of Sidmar obtained and with the general results of the metallurgical industry.




Auteur: Lescrenier, Gaëlle & Daneels, Marnix
Herkomst: KULeuven, CIT, WMAG (Heverlee)
Referentie: Referentie