Phosphorus is essential for both plant and animal life – and so for us humans, too. As this element is becoming scarcer and scarcer, REMONDIS has hugely intensified its efforts to recover phosphorus.
REMONDIS is not only one of the leading “P recyclers” in Europe as a result of its sewage sludge recycling activities for agricultural businesses, it is also an important supplier of the precipitating agent, ALUMIN. This substance is needed to eliminate phosphate from wastewater at sewage treatment plants. In 2013, REMONDIS Aqua began research work on its TetraPhos® process and has now found an economical way to recover high quality phosphate from sewage sludge ash on an industrial scale, namely using phosphoric acid. Practically all other phosphate products are made from this important, multi-functional mineral acid, in particular fertilisers and animal feed. Demand for phosphoric acid lies at over a million tonnes per year in Europe alone.
The REMONDIS Group working as a team: the REMONDIS TetraPhos® process was developed together with REMONDIS Aqua’s sister company, UCL, and then optimised at EURAWASSER Nord’s sewage treatment plant in Rostock.
In just a few decades’ time, supplies of mineral fertiliser will have become scarce in many countries around the world which will mean that food production will also decrease. The key nutrients in mineral fertiliser are nitrogen, potash and salt of phosphoric acid, the so-called phosphates. These are obtained from phosphate ore, which is primarily mined in North Africa and Russia, and is of course – like all raw materials – finite. Unlike the majority of other raw materials, which are used by industry to manufacture consumer goods, phosphate cannot be substituted. Phosphates are essential for all life forms on our planet – for the smallest cell, for human bones, for the tusk of an elephant. Raw phosphate ore, however, is running out: if demand continues at its current rate, reserves that can be affordably mined will have been used up in the near future. New solutions need to be found so that the world’s ever growing population can continue to be fed and we can reduce our dependency on the Earth’s scarce phosphate reserves, especially in the densely populated countries of Europe which have so few natural resources of their own.
What is particularly special about REMONDIS’ innovative TetraPhos® process is the fact that sewage sludge ash containing phosphate is treated with diluted phosphoric acid. Up to 50 percent of sewage sludge ash is made up of phosphates which dissolve in the diluted phosphoric acid. The phosphoric acid solution is enriched with the phosphate from the ash and then treated in four different stages. Various products are available at the end of the process including RePacid® phosphoric acid, used to produce phosphates for manufacturing fertilisers, and gypsum for the building supplies industry as well as iron and aluminium salts.
This new process was developed in REMONDIS’ own research laboratories with the support of UCL Umwelt Control Labor in Lünen and then optimised at the central sewage treatment plant in Rostock in cooperation with EURAWASSER Nord. This patented method was presented to the public for the very first time at the REMONDIS EURAWASSER Forum, which was held in the German city of Bremerhaven in September. Josef Lehmkuhl, REMONDIS senior consultant and inventor of the process, presented REMONDIS’ TetraPhos® at the event during which he explained just why it is so special: the RePacid® phosphoric acid created during the process can be reused to treat new ash. This means there is no need to buy in new conventionally produced phosphoric acid making the whole procedure, of course, incredibly economical. Not only up to 500kg of RePacid® phosphoric acid can be produced from 1,000kg of ash but also over 500kg of gypsum for the building supplies industry and, for example, iron and aluminium salts that can be recycled as precipitating agents to treat wastewater at sewage treatment plants. REMONDIS’ TetraPhos® process is, therefore, an ideal addition to a mono-incineration facility at sewage treatment plants. By combining incineration processes and TetraPhos (especially in combination with fluidised bed incineration systems), sewage sludge can be used for materials recycling.
From left to right: Andreas Bankamp, Managing Director of REMONDIS Aqua GmbH & Co. KG, Dr Martin Lebek, also a member of the senior management team at REMONDIS Aqua GmbH & Co. KG, Sabrina Lohmar, Project Manager (industrial division) at REMONDIS Aqua, and Josef Lehmkuhl, Senior Consultant at REMONDIS, at the REMONDIS EURAWASSER Forum in Bremerhaven
The REMONDIS TetraPhos® process is highly efficient, environmentally friendly and cost-effective, helping at many different levels to conserve our planet’s natural resources. It closes a number of material life cycles and, over the long term, will help to make Europe less dependent on phosphate imports and the spiralling raw phosphate prices. As Josef Lehmkuhl repeatedly demonstrated, there are other promising uses for this process such as combining RePacid phosphoric acid with mineral products from processed abattoir waste, such as bone meal ash or Polymat sediment, to produce high purity fertilisers.
Contributing towards conserving our planet’s natural resources: REMONDIS’ patented TetraPhos® process.
“REMONDIS’ new TetraPhos® process once again highlights our philosophy at REMONDIS, namely that sewage treatment plants are no longer to be seen as a facility for disposing of products but for recovering clean water, energy and minerals,” explained Dr Martin Lebek, senior manager at REMONDIS Aqua GmbH & Co. KG. REMONDIS Aqua has already been granted four patents. From the spring of 2015, the company will, in cooperation with HAMBURG WASSER, be testing the new process under normal working conditions at a pilot facility at Köhlbrandhöft sewage treatment plant in Hamburg.