Last month a study was published in Ecology Letters, looking at the lakes of North America and Europe.
It found that populations of cyanobacteria, better known as blue-green algae have increased significantly since the 1800s, confirming fears of a significant danger to our environment. This overgrowth of algae starves the water of oxygen and suffocates marine life around it. But how has this overgrowth come about?
The answer is relatively simple. Through the invention of industrial fertilizer as part of the rise of intensive farming, nitrogen was subsequently introduced into the food chain, consumed by the population and then excreted into the wastewater. This was later true of phosphorous too, as the harmful chemical was used in more and more agricultural and industrial techniques and products. The release of these nutrients into our wastewater increases the proliferation of algae.
In the last 20 years scientists have worked to solve this problem by accelerating the natural biological process that occurs during sewage treatment. They have termed it Biological Nutrient Removal (BNR). Through this technology the microbes that consume the nutrients in sewage are encouraged to consume greater quantities through the control of the quantity and timing of their oxygen supply. This has proven a far more efficient way of dealing with our sewage, however it is still not enough to remove the vast quantities of nitrogen and phosphorous still getting through the process. This currently requires something called ‘chemical dosing’ where the wastewater is dosed with a chemical that can remove nitrogen and phosphorous. The chemical is ferric oxide, better known as iron. This method was able to stall the problem momentarily but, in the UK and the rest of the developed world iron filings are becoming more expensive. This combined with the costs to remove the iron from the treated water has rendered the practice unsustainable.
Currently governments in developed countries have a requirement for the volume of effluent allowed to remain in the treated water. Typically raw sewage arrives at a treatment plant with 7-12mg of phosphorous per litre. This must come down to a minimum of 2mg per litre in the treated water. Up to now chemical dosing has been able to achieve this, however with the rising cost of iron filings combined with expensive treatment to remove the iron filings from the treated water the process is looking far less attractive. However this is not the final nail in the coffin. The developed world, led by Europe and the United States has recognized that phosphorous at a level of 2mg in our treated water is still causing untold damage to the environment and is no longer acceptable. The phosphorous still combines with nitrogen to encourage the growth of algae that continue to use up all available oxygen in the water.
What then, is the solution? At Plantwork Systems, our answer to this problem is called NUTREM, an important advancement in Biological Nutrient Removal that reduces phosphorous in the treated water to below 0.5mg per litre and nitrogen below 10mg per litre. NUTREM is a fully working solution to the problem of blue-green algae that has been outlined in this recent study. More information on NUTREM and our advances in Biological Nutrient Removal can be found here.