UNDER DIFFICULT CONDITIONS

At first, various so-called "HSOG" measures were initiated by the competent local government Environment Agency in collaboration with HIM GmbH ("HSOG" is the German abbreviation for the Hesse Public Safety and Order Act). These were immediate measures under waste management legislation for eliminating acute potential danger, such as those carried out after traffic accidents with consequences for the environment.

Following this, the Environment Agency commissioned HIM GmbH to record and sample the chemicals that were still on the site so that the remaining pollution potential could be estimated and the disposal priorities and types determined.

It was soon seen that a flexible and uniform solution was the right thing for these waste disposal measures. In December 2000 HIM GmbH provided the recording and sampling services for a period of over one week with 5 employees. The first on-site inspections showed just how demanding this project was to be: after the bath extractors were switched off, chemical reactions from the acid and alkaline vapours and gas exhalations from various sources resulted in mist in the production rooms.

For this reason, safety at work had the highest priority: to avoid endangering the health of our employees the sampling was carried out under full protection and with gas masks.

This solved a delicate problem from the start. During sampling and recording work unsecured containers with waste chemicals were taken from garages and a wooden hut, among other places, and placed on previously cleared areas in the main workshop; the containers were then covered with plastic sacks to protect them from rain.

About 220 samples of liquid waste were taken from galvanising baths and storage containers and, after various preliminary analyses (TOC and pH values, cyanide), were formed into mixed samples in accordance with waste and treatment type in the HIM Frankfurt laboratory and tested there for the CP treatment.

About 70 additional samples of unknown solids/liquids were analysed in the Biebesheim laboratory for acceptance in the local social waste incinerator (exclusion criteria, X-ray fluorescence analysis, pH value, cyanide).

It was possible to allocate the majority of the recorded residual chemicals with the help of the product description and the existing safety data sheets from the respective manufactures, thus avoiding an even longer analysis period.

Following the two-month analytical evaluation the resulting list of chemicals contained approx. 980 recorded single items of residual and galvanising chemicals, each of which was shown with a corresponding disposal and packaging standard. Analysing, evaluating and allocating to chemical groups were tasks that took a great deal of effort. The emphasis here was on combining single liquid batches into larger transport units to achieve the lowest possible transport costs with the same treatment expenditure. The HIM collection location in Frankfurt was put to good use as a logistical functions provider.

The above description shows how important competent sampling and analyses are for efficient waste disposal. Cost and technical aspects, health and safety at work and transport standards play a part as well, as does the interplay between them all.

The salt residues, sludges, filter gravel and used ion exchangers that were collected in different containers turned out to provide special challenges from the aspect of waste disposal when they were being recorded and analysed.

Because the operator had collected and mixed these materials in barrels or containers without, to a great extent, paying any attention to the contents, the result was a very heterogeneous waste mixture with incompletely assessable waste properties and potential risks (reactions and gassing during mixing). In order to guarantee no-risk waste disposal, these materials had for this reason to be transported to HIM's Biebesheim special waste incinerator for a controlled reduction of the potential risks.

There was a similar picture with the examinations of the sludges in the treatment and storage tanks. The former operator had mixed and stored extremely different scouring water and wastewater from the galvanising plant without, to a great extent, considering the chemical-toxic properties and reactions.

For example, sludges from the wastewater treatment plant that were polluted with cyanide were found on delivery in 2000 to contain chromium (III) compounds, in addition to cyanide and in some cases were in an acid medium. Because of the prussic acid that is created in the acid medium, the chemical treatment of mixtures of this kind is extremely dangerous and the combination with chromium (III) compounds and complex cyanides makes it complicated and expensive.

Compounds of cyanide, chromium (III)/(VI), lead, copper, nickel, tin and zinc were detected as bath chemicals with an increased risk, and hydrazine was also used in a galvanising line.

The most important chemicals used for surface conditioning (pickling, activating, passivating) and for setting the pH value were, among others, caustic soda, hydro-chloric acid, sulphuric acid, ammonium fluoride solution and nitric acid.

Following an examination of the possibility of the treatment on site of slightly contaminated swills and wastewater, HIM was able to dispose of these as well. We did not realise the possibility of detoxifying/neutralising different potentially treatable sludges in the wastewater treatment plant that was installed on the site.

The reasons for these decisions included the following:

the necessity of a complicated mechanical-electronic function test of the existing installation, which would have taken several days, with an uncertain result with regard to the applicability and necessary repairs uncertainty with regard to the treatment capability of the existing installation to achieve wastewater from the existing highly contaminated swills capable of being introduced into the municipal sewage system in accordance with the conditions for this stipulated by the local authority costs structure similar to calculatable waste disposal through HIM.

The decision against on-site treatment was therefore taken after weighing up technical, ecological and economic aspects.

For reasons to do with health and safety at work, the relevant swills were localised and eliminated in order reduce as quickly as possible the "mist formation" in the production rooms that was referred to above.

Environmental protection in practice is not necessarily in contradiction to responsibility for costs and efficiency. However, this project showed that things take time to achieve. It showed that quality-oriented work can, in certain circumstances, take a great deal of time.

The barrels filled with residual chemicals, some of which were open, that were found in the hall area next to a galvanising train show just how materials that can affect the environment were handled in practice. In this case as well extremely different concentrates (chromium acid swills, cyanide swills and other concentrates) were stored without any system.

During extraction and packing work it was found that there were considerable amounts of scrap and contaminated resources in some galvanising baths. In addition, 2 chromate baths in the plastic galvanising plant had crystallised out to about 70% and emptying/cleaning the bath was not possible with taking it apart. Another chromate bath had crystallised out to about 30% and it took a considerable length of time to empty and clean this bath.

Other baths and swills also showed considerable amounts of salt crusts inside and outside which had to be removed mechanically. The waste found here was assigned to the corresponding waste groups and was disposed of. As far as possible, the waste was assigned to an underground landfill. Where components were found which might cause explosive gas-air mixtures the waste was brought to the Biebesheim special waste incinerator.

With regard to the complexity of the task and the flexibility of the solution this project was a challenge, even for an experienced waste disposal services provider like HIM GmbH. And not just because of the total volume of over 1 million EUR for transporting, packing, disposing of and analysing since May 2000. Pressure of time was always a problem, as was the fact that the plant was in a mixed residential/commercial area. In the framework of the project it once again became clear that a good waste disposal solution must take into account all the economic, technological and ecological aspects. In view of the complexity of this task, the competence of the employees and the obligations towards the customer plays an important part. Standardised processes would not have got us very far.