The Houtrust waste water treatment plant (WWTP) was originally built in 1967. It was partially renovated in 1988 and 1995 to meet the (environmental) demands of that time. Even so, around 2000 the treatment plant was showing its age and was no longer capable of effectively treating the waste water flow from the homes and companies in The Hague. Moreover, the plant could not meet the more stringent European requirements for nitrogen removal. This was sufficient reason to totally refurbish this waste water treatment plant. In 2007 and 2008, the Houtrust WWTP was drastically renovated. With the current treatment capacity of 430,000 pollution equivalents (p.e.) the plant is able to treat the waste water from the residents and companies of The Hague and surrounding areas. On a site that covers 5 hectares, the Houtrust WWTP can treat on average almost 79,000 cubic metres of waste water a day, in other words the capacity of more than 2,600 trucks.
The biological waste water treatment process is as ingenious as it is simple: we employ billions of micro-organisms that do the actual work for us, they literally consume the waste material in the water. In fact this is exactly what happens in nature, but here in a controlled way and on a large scale.
The entire treatment process is fully automated. The operator can log in remotely and, if required, intervene. Pumping stations transport the waste water from the municipalities to the WWTP.
Immediately on arrival, remove the large solid materials (paper, plastic, wood, textiles) from the waste water. After being cleaned, this waste material is stored in containers and transported to a waste incineration plant outside of the WWTP.