Water Journal : Current May 2016
www.awa.asn.au 105 executive summary water and energy Energy and nutrient factory at Netherlands' Amersfoort WWTP RECOVERY OF ENERGY AND NUTRIENTS FROM WASTE-ACTIVATED SLUDGE AND WASTEWATER. L Kox, B Geraats Amersfoort wastewater treatment plant (WWTP) in the Netherlands is owned and operated by Dutch water board Vallei & Veluwe. In 2013, Eliquo Water & Energy was awarded the project to upgrade the existing wastewater and sludge processing facilities and transform them into a regional sludge processing hub that acts as an 'energy and nutrient factory , using innovative technologies to recover energy and nutrients. TECH INNOVATION Energy recovery was enhanced by the application of Lysotherm thermal pressure hydrolysis technology to the anaerobic digestion process. The application of Lysotherm thermal pressure hydrolysis brought the following advantages: Increased capacity of existing digester volume; Increased gas production; Reduced production of biosolids; Increased sludge dewatering capability; and Reduced chemical consumption for sludge dewatering. In contrast to traditional systems, Lysotherm does not require steam as a driver. Instead, existing waste heat of the exhaust from the Combined Heat and Power units is used as an energy source. Avoiding the need for steam generation has a positive impact on economic viability, safety requirements, plant availability and operability. It also improves energy efficiency, as no gas is required to boil water, leaving more for the generation of electricity. Other advantages are the modular and off-site construction, continuous process operation with very limited maintenance requirements, and no additional odour emissions. The combination of this technology with the processing of import sludge resulted in the WWTP becoming energy-positive. P RECOVERY Uncontrolled formation and deposition of struvite causes significant ongoing maintenance costs at existing WWTPs. With the upgrade, phosphorus is recovered by means of Pearl technology, which creates a valuable fertiliser called Crystal Green. It will generate non-regulated revenue, combined with a guaranteed long-term off-take agreement through which the product marketing and distribution risks are transferred to the technology provider. It also prevents uncontrolled deposition of struvite occurring, resulting in significant savings in avoided maintenance costs. In addition, it reduces the amount of chemical sludge that is formed when phosphorus is removed from wastewater by chemical dosing via conventional removal methods and improves dewaterability of the digested sludge. SUSTAINABILITY PAYS A combination of both technical and commercial innovations allowed all of the water board s project objectives to be met. These were: 1 A regional sludge processing hub is created while re-using the existing assets (digesters); 2 To become energy-positive, by applying Lysotherm technology; 3 To recover phosphorus in a commercially viable way by creating a fertiliser product that is sold via a novel commercial arrangement; 4 To reduce overall sludge processing costs by producing less sludge, enhancing the performance of the existing digesters; and 5 To pay back capital investment in less than seven years. Luc Kox is an Engineer and Bert Geraats is the Technology Manager at Eliquo Water & Energy BV. This paper is being presented at Ozwater'16 in Melbourne, May 10--12. To read the full article, visit the Water e-Journal at bit.ly/e-Journal The Amersfoort WWTP is leading the way in resource recovery.
Current Feb 2016
Current August 2016