SHARON - Dokhaven, Rotterdam
SHARON - Dokhaven, Rotterdam
Nitrogen removal with zero sludge
Operational for over 10 years, the SHARON facility at Dokhaven Waste Water Treatment Plant (WWTP) was commissioned by STOWA in response to legislation requiring nitrogen removal to be optimised.
A study of the nitrogen balance of the WWTP showed that a significant fraction of the nitrogen is recirculated from the sludge digestion towards the activated sludge tanks. This amounts to 15 % of the total nitrogen load of the WWTP. Therefore removing this load will directly result in an equivalent decrease of the total nitrogen load in the effluent.
Providing a 40% reduction
The SHARON process was identified as the most cost effective technique. It involves a high active process for nitrogen removal operating without sludge retention. Due to differences in growth rates, nitrite oxidisers are washed out of the system whilst ammonia oxidisers can be maintained. This results in nitrogen removal over nitrite instead of nitrate.
Following the implementation of SHARON, the total Nkj discharge load of the Dokhaven WWTP dropped by 40%. As a result the water authority ZHEW is able to meet the required nitrogen removal demands.