Objective
Experimental study of whether the purification of ground water contaminated by leakages and accidents as a result of coke production is possible with the aid of biological purification techniques.
During the entire testing period it turned out to be possible to decompose organic compounds, ammonia and nitrates in biological disk reactors.
The decomposition of the supplied amounts of BTX gave no problem at all at an influent concentration of 20.000 ug/l and a load of 1,0 g/m{2}/day.
Assuming a sufficient capacity of this installation it was possible to reach a total nitrogen-concentration in the effluent of 15 to 20 mg/l. That is amply sufficient, because the limit is 25 mg/l.
In the series of BTX-decomposition, nitrification and denitrification the nitrification-reaction showed to be the restricting one.
In the beginning of September 1993 the investigation of the biological purification of coke-ovensite-groundwater was finished. Hoogovens Ijmuiden has decided to purify the contaminated groundwaterflow in two steps.
The first step is the biological decomposition of BTX and part of the COD by means of rotating discs as was tested in this research project. The effluent of this first step will be purified in a combined installation together with other wastewater streams containing nitrogen compounds.
As a result of leakages, accidents and acts of war, the ground water under one of the coke ovens at Hoogovens Ijmuiden is highly contaminated by NH3, CN-, phenols, PAH and benzene, toluene and xylenes.
To prevent these contaminants spreading via the ground water, extraction wells need to be installed at a number of points. The extraction of sufficient ground water from these wells ensures that the contaminants do not spread any further and are eventually eliminated from the ground water.
In recent years, a number of ways have been examined of purifying the extracted ground water.
The most promising method was studied last year in a pilot trial. This used an installation to strip the ground water with air and then biologically purify the air, now charged with volatile substances, with the aid of compost filters.
In terms of securing a reliable process, the results were not satisfactory. Air stripping gave rise to many problems because the ground water was extremely hard; although the problems were finally resolved, intensive supervision of the installation continued to be necessary.
In addition, the levels of volatile substances such as benzene, toluene and zylenes in the ground water proved to be so high that the stripping air could not be purified with the aid of compost filters. The quantities of compost required made the process uncontrollable.
Furthermore, this method did not remove contaminants such as cyanides, phenols and ammonia from the ground water.
Recently, research into the purification of waste water from incineration plants has shown that it is possible to break down not only volatile organic compounds but also cyanides, phenols and ammonia.
Research into the biological purification of contaminated ground water may lead to the design of installations that enable contaminated ground water of differing compositions to be purified reliably without the need for intensive long-term supervision.
The project is based around a standard biological purification installation with a number of stages arranged in series. The installation must be enclosed in a housing maintained under a slight under-pressure to prevent the escape of contaminated air, in particular air contaminated by benzene. The extracted air will be purified using a compost or carbon filter.
In order to remove all components from the ground water to a sufficient degree, research will be carried out into the number of stages needed and the required residence time, the oxygen supply required and the additives necessary in each stage.
The relevant data will be obtained through regular sampling and analysis of the inputs to and outputs from the consecutive stages.
Call for proposal
Data not availableFunding Scheme
Data not availableCoordinator
1970 CA Ijmuiden
Netherlands