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Democase Rotterdam

All aspects of resource recovery near a city farm


Evides Industriewater built a pilot in Rotterdam where all aspects of resource recovery were integrated: water reuse, nutrient recovery and energy recovery.

Due to the closure of the 'Uit je eigen stad city farm', this democase was moved to Harnaschpolder in Delft were the demonstration and research was continued. 


Municipal wastewater
Municipal wastewater from an outer dyke area in Rotterdam is taken from the sewage system and stored in a buffer tank. In this influent buffer tank, sedimentation of coarse parts (including moist toilet paper) is first accomplished by placing the supply pipe to the pilot at a high position. The wastewater is pumped into the pilot at 2.5 m3/h and first passed over a drum sieve where the coarse parts are removed.

Water treatment
The wastewater then goes to an electrocoagulation system in which iron or aluminium is brought into solution and will coagulate with the particles, the COD and the phosphate in the wastewater. For the processing of the electrocoagulation sludge, we want to investigate various routes, namely fermentation and pyrolysis (both techniques to be performed elsewhere than the NEREUS pilot at Marconistraat).

The wastewater treated by electrocoagulation then goes first through a pre-filter for protection and then to the nanofiltration pilot system, which consists of two stages (first stage 2 membrane modules, second stage 1 membrane module). We have membranes with Molecular Weight Cut Off (MWCO) values of 400 and 800 Da at our disposal.

Nutrient recovery
New phosphate recovery techniques will be tested on the nanofiltration concentrate, initially on a laboratory scale. The permeate of the nanofiltration pilot system passes through a softener, where calcium and magnesium are removed, prior to the reverse osmosis (RO) membrane.

This membrane makes a very clean water product, the RO permeate, that will be delivered to the city farm Uit je Eigen Stad (UJES). The concentrate of the reverse osmosis (RO), mixed with concentrated urine from a waterless urinal at the restaurant of Uit je Eigen Stad, will be used for an algae culture. Which algae we will grow exactly has yet to be determined.

At the Harnaschpolder waste water treatment plant in Delft, experiments are being carried out into the enzymatic conversion of fine sieve screenings to carbon source, which can be used by the denitrifying bacteria in the wastewater treatment plant. Also anaerobic digestion tests could take place at this location.

Within this democase, we cooperated with the following local observer partners:
• Gemeente Rotterdam
• Hoogheemraadschap van Delfland
• Hoogheemraadschap van Schieland en de Krimpenerwaard
• Waterschap Hollandse Delta
• Logisticon Water Treatment B.V.