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Manure digesters still locked after amphetamine discovery
The situation for 23 co-digesters in the north of the country that were shut down after the discovery of amphetamine in the digestate is still unchanged and hopeless. In the meantime, the damage continues to rise into tens of millions. The cause is still unknown, although it is suspected that the substance is formed naturally during the fermentation process. The link that was previously made with the dumping of drug waste does not seem realistic.
As early as October 2023, it was announced that minimal concentrations of amphetamine had been found in the digestate at various co-digesters in the provinces of Friesland, Groningen and Drenthe. Amphetamine is a synthetic drug. The discovery led to the installations being shut down and the residual digestate product not being allowed to be disposed of. A second study, the results of which were announced in early December, again showed concentrations of this substance, which further extended the production stop. February is now in sight and there is still no clarity about the situation.
A few sugar cubes per co-fermenter
The amphetamine levels found vary per installation, but are very minimal. What amounts of amphetamine concentrate are we talking about? This would involve values around 10 to 50 micrograms of amphetamine per kilo of digestate at the companies that were closed. Values of less than 10 micrograms are virtually impossible to measure. According to Robert Goevaers, director of Platform Groen Gas, it concerns a few sugar cubes in an entire installation. "As an example, we take a location with the highest amphetamine values that have been measured. This concerns a concentration that is equal to approximately six sugar cubes, or: the amount of amphetamine that is spread as digestate on one hectare of land is one fifth of a sugar cube”. The standard used according to legislation and regulations is 0, which explains why the co-digesters were shut down.
In the follow-up study that was carried out in October, the values were approximately the same, but on average slightly lower and again there were no peak values. If drug waste had been mixed during that period, the value would peak.
Dumping drug waste is not obvious
The results of the first investigation initially suspected drug waste, but this is now unlikely, although nothing is concrete yet. The strange thing about the whole thing is that amphetamine was found in different concentration levels, but otherwise no other residual products or waste were found that you would expect when dumping drug waste. Moreover, no harmful substances have been found in the products or manure that enter the digester, but they have been found in the digestate. This is evident from research by the companies themselves, as the environmental services of the provinces have not investigated the inflow from the digesters. In any case, there seems to be some confusion here, because the first research was already carried out in the summer of 2023 and the results of the research were ready afterwards. Only in October were the digesters closed and a follow-up investigation into only the digestate was carried out by the environmental services, an insider reports. State Secretary Vivianne Heijnen denied this in mid-December when the news reached the House of Representatives after the BBB asked questions about it. Various environmental services collaborate with other chain partners in the research and this takes time.
Heavy metals were also found in co-digesters during the research. However, this is not true, according to an insider. During the research, the measurements were carried out correctly, but the measured values of the research were compared with the wrong standards during the research, according to the insider. This only became known later.
By-product during fermentation process
People from the sector and the interest group Platform Groen Gas, the interest group for green gas producers, suspect that the amphetamines found are produced naturally in the digesters. To date, there is no known research that shows this, as outgoing Minister Adema also announced in mid-December after questions from the VVD. This would then be a by-product of the fermentation process, but this is still uncertain. "If these substances cannot be found in the incoming flow, but can be found in the outgoing flow, then they are created in the production process," says Goevaers. Comparisons have been made and there are two things that the digesters have in common. "It is mainly digesters that run at a higher temperature where amphetamine is found. Another similarity we saw are parties that used straw with a high protein content in their digester. But this needs to be investigated and is not yet concrete." Another possibility, according to Goevaers, is that it results from the use of process water. This cannot be ruled out because it may also contain minimal amphetamine values.
A similarity was also visible in the digesters where relatively the highest values of amphetamine were measured. "These digesters are characterized by the fact that the end product (digestate) is partly used to initiate the new fermentation process," Goevaers notes. Theoretically, this means that the residual product containing the amphetamine can accumulate, which explains the increase in these fermenters. However, this remains a suspicion and research must provide more clarity.
Huge damage to the sector
In the meantime, the 23 digesters spread across the three provinces have still been idle since mid-October. Production will only restart if it meets all the requirements of current legislation and regulations. The damage now amounts to tens of millions of euros, if not more. In addition, it is yet another setback for the already overcrowded fertilizer market, which needs every outlet.
In addition to uncertainty about financial damage, there is also a lot of uncertainty about the amphetamine that may be formed in digesters. In the context of the Opium Act, it is often thought that this substance is not permitted and is therefore problematic. From a fertilization perspective, according to Goevaers it can be concluded that amphetamines have been formed in fermentation since fermentation has existed. According to him, this has never led to any problem, so it can simply be ridden out, partly because it is known that amphetamines break down quickly under the influence of light and air.
Jesse Torringa
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