ZUG, Switzerland--(BUSINESS WIRE)--At the beginning of this year, AVA-CO2 together with the Swiss Federal Office for the Environment (FOEN) and Zurich University of Applied Sciences published a study that demonstrated the advantages of hydrothermal carbonization (HTC) for sewage sludge treatment. The company has now achieved a further milestone in the very important field of phosphorus recovery. The groundbreaking "AVA cleanphos" process is the result of months of research and development, and was only made possible by the AVA-CO2 HTC process. The most important innovation of "AVA cleanphos" is the replacement of the substrate! In contrast to other methods, AVA-CO2 does not obtain phosphorus from the sewage sludge or the sewage sludge ash, but directly from the HTC char. This allows for a phosphorus yield of over 80%, with less use of acid, reduced energy costs and lower investment costs. In addition, the "AVA cleanphos" solution enables the production of phosphoric acid that is free from heavy metals and without an additional cleaning stage – a significant difference compared to the method of recovery from sewage sludge ash. A further outstanding advantage of the "AVA cleanphos" solution is that sewage sludge in the form of phosphorus-free HTC char can also be used in co-incineration as a substitute for fossil coal in the future.
On 11 September, Thomas Kläusli, Chief Marketing Officer of AVA-CO2 Schweiz AG, will present the "AVA cleanphos" process as a world first at the i-net Cleantech Technology in Basel, Switzerland. His presentation "Wirtschaftliche Phosphor-Rückgewinnung mit Hydrothermaler Carbonisierung" (Economical Recovery of Phosphorus with Hydrothermal Carbonization) will be held at 12:25 p.m. One week later, the innovative method will be presented to German industry professionals at the VDI-Klärschlammtage in Straubing at 1:50 p.m. on 18 September 2014.
Phosphorus from HTC char in a three-stage process
The "AVA cleanphos" process is a simple, three-stage method that uses tested and well-known technologies such as acid leaching, nanofiltration and concentration. HTC char is fundamentally different from the slag produced by sewage sludge incinerators. An energy-intensive grinding system does not have to be used for preconditioning, since HTC char is not slag with corresponding vitrification. A simple grinding system, not unlike a kitchen mixer, is sufficient, which leads to considerable energy savings.
With the "AVA cleanphos" process, acid leaching of phosphorus from the HTC char takes place after preconditioning. The phosphorus does not react during the hydrothermal carbonization and is therefore not bound in a stable glass matrix but is free. This permits a considerably lower use of acid for the leaching of the phosphorus, with corresponding cost savings. However, this process also displays further advantages, such as e.g. the high purity of the phosphoric acid. Since the HTC char has a high affinity for heavy metals, only 8-10% enter into the phosphoric acid and the rest remain in the HTC char. In the case of conventional methods, over 70'% of the heavy metals remain in the phosphoric acid. In the second stage, the preparation with nanofiltration causes the phosphoric acid to be separated from the metal sulfates. These metal sulfates (e.g. aluminum or iron) can therefore be recycled and returned to the sewage treatment plant as precipitants. In the third and last stage, the concentration of phosphoric acid is increased from 5% to 50%-75% using standard technologies.
"As a result of our 'AVA cleanphos' process, phosphorus recovery will be called into question as an argument for mono-incineration plants in the future. In addition, there is a process available today that allows phosphorus to be economically recovered from sewage sludge. An achievement for which politics and industry have waited for a very long time. Our process also opens up entirely new possibilities for industry, e.g. in the cement sector, since our phosphorus-free HTC sewage sludge char can replace brown or black coal. In this way, CO2 emissions can also be reduced," explains Thomas Kläusli. "AVA cleanphos" clears the way for sewage sludge recycling, leading away from pure disposal.
Brief profile of AVA-CO2 Schweiz AG
AVA-CO2 offers solutions for the sustainable use of sewage sludge and other biomasses for energy generation worldwide. As a pioneer in hydrothermal carbonization (HTC), AVA-CO2 plans, builds and operates HTC plants on behalf of its customers. These facilities efficiently and profitably turn sewage sludge and plant residues into CO2-neutral HTC char. With "AVA cleanphos", the company offers an innovative and economical process for phosphorus recovery on the basis of HTC. The company has its headquarters in Zug, Switzerland, and a subsidiary in Karlsruhe, Germany. In October 2010, it put the world's first industrial-scale HTC plant into operation. The subsidiary AVA Biochem with its headquarters in Basel, Switzerland, produces the platform chemical 5-HMF on the basis of HTC technology.
About Thomas Kläusli
Thomas Kläusli has many years of international experience in the finance and technology sectors. He began his career at Asea Brown Boveri, where he played a key role in building up the ABB Treasury Center as well as the ABB Treasury Consulting Group. Subsequently, he switched to the telecommunications sector, where he was responsible for partner business and product development, then later for customer relationship management and the development of convergence strategies. Thomas Kläusli was born in Zurich and has a Bachelor of Science from City University and an MBA from the McCombs School of Business. He speaks fluent German, English, French and Spanish.
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