SHARON - a sustainable system – Garmerwolde, NL

Grontmij, as main contractor and owner of the proprietary SHARON technology, is responsible for the design and construction of the SHARON system at the wastewater treatment plant in Garmerwolde, the Netherlands. Grontmij will also operate the SHARON for one year.

The Garmerwolde wastewater treatment plant (WWTP) is being refurbished to meet future effluent standards. Part of the refurbishment is the construction of a Stable High rate Ammonia Removal Over Nitrite (SHARON) system for treatment of flows produced at the sludge dewatering and sludge drying facilities at Garmerwolde. Locally produced sludge is anaerobically digested and, together with sludge imported from other facilities, dewatered and dried. The filtrate produced in the sludge dewatering process, together with the condensate produced in the sludge drying process, contributes approximately 34% of the total nitrogen load to WWTP Garmerwolde. The Waterboard Noorderzijlvest, who owns WWTP Garmerwolde, has selected the SHARON process as preferred method for filtrate and condensate treatment on the basis of overall treatment cost, high guaranteed ammonia removal efficiency, stable operations and proven track record. SHARON is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has several advantages: • oxidation to nitrite saves 25% on aeration energy; • denitrification of nitrite saves 40% on BOD addition; • denitrification of nitrite at high temperatures reduces sludge production by 50%; • simple process with high process stability.