Water is an indispensable part of brewing beer. Beer consists of 93% water, making it a significant component of the brewing process. For decades now, Heineken has been purifying the water left over after the beer has been brewed with its own installation. Wageningen Environmental Research (Alterra) is the knowledge partner for a new project by Europe’s largest beer brewer and the province of South Holland to improve waste-water purification by developing a purification marsh.
With this project, the partners are anticipating future standards and the Green Circles' ambitions of creating a climate-neutral brewery and pleasant surroundings. The future marsh means the water will be suitable for connecting to the nearby ditch system while it will also fulfil a role in biodiversity, recreation and biomass production.
The project’s technical and financial viability is currently being explored. Zuid-Hollands Landschap and Hoogheemraadschap Rijnland are also interested in this project succeeding, due to the multifunctionality and positive impact it has on the region. Alongside further purifying the waste water, the development also offers the possibility of enhancing biodiversity and a nature reserve with higher natural values than is currently the case will develop on the site. The marsh can have an enhancing effect as a stepping stone for the adjacent, once robust, transitional zone the Elfenbaan. Moreover, the marsh fits within the ditch system surrounding the factory site and is set to become a source for species that will boost the ditch system’s biodiversity. The marsh is also linked with the purification ditch, another project being executed within Green Circles.
The purification marsh can also be used for recreation and can be used by Heineken employees and other visitors to enjoy pleasant walks in natural surroundings. Mowing will be carried out annually and the clippings can be used to produce energy and make the beer production process more climate neutral. The marsh is designed in such a way that it can also store water.
The design takes the current situation into account and ties in with the landscape of meadows and ditch patterns. The current pattern has been reversed, with the ditches becoming dykes to be walked on and the meadows being submersed in water. Although there are footpaths which usually go over the dykes, boardwalks are being laid in a number of places. A birdwatching hut has been planned on the north side next to one of the larger ponds. The plants in the marsh (helophytes) will absorb the phosphorus and nitrogen present in the waste water, thus further purifying the water.
The design has two water levels. From the purification, the water is conducted through an open drain and from there into the forebay. While travelling through the drain, the warm water is already able to cool down and absorb oxygen. The cooling continues when the water flows from the capture basin into the first large basin over a structure. The water is raised between dykes in the largest section.
In the south at the modern windmill it flows through a drain and a weir into the smaller, lower basin. From there it is pumped into the collector basin. Sand only has to be moved within the area while no sand is removed.