Water reuse and aquifer storage for greenhouse irrigation

SUBSOL

Waste water source

Rainfall as well as a neighbouring sugar factory (Suiker Unie) producing large volumes of waste water between September and January provided a potential water source. However, this availability of water is out-of-phase with the projected demand of the greenhouse horticulturalists (April-August, depending on the moment of drought). The salinizing coastal area prohibits the use of ground- and surface water. Therefore, the reused wastewater will be stores in a brackish aquifer with a newly developed configuration (‘ASR-Coastal’).

Distribution System

The rainwater is temporary stored in the water bassins of the greenhouses. After passing a sand filter, the water is in infiltrated under gravitation into the ground. Treated effluent of the sugar factory Suiker Unie is delivered via a 5 km long and 315 mm diameter HDPE distribution loop to an aboveground 200 m³ storage tank. When the effluent reaches a threshold level in the storage tank, water is delivered from here to the pumping station. Here, the water can be delivered to a standpipe, which provides the pressure to infiltrate water into the subsurface through the ASR-wells. Whenever there is a demand for irrigation water, the treated effluent can be delivered to horticulturalists in three ways:

1. The treated effluent can be delivered directly to the horticulturalists
2. water stored in the storage tank can be delivered back to the piping network and can subsequently be provided to the horticulturalists
3. Treated effluent stored in the subsurface can be recovered through the ASR-wells

Farming system

The area of 'Nieuw prinsenland' harbours modern greenhouse horticultural companies.

Costs

Based on a cost analysis, a positive business case for ASR-Coastal was found. The costs based on an average water use of 100,000 m³/yr and a maximum capacity of 200.000 m³ are estimated on 0.37 euro/m³, versus 0.99 euro/m³ for above ground storage in foil basins. This results in a yearly benefit of 62,000 euro/yr.

Type of agreement

At the Dinteloord water system, many parties are involved with different roles. Veolia is operating the waste water treatment.  TOM (developer of the greenhouse area) and KWR operate the ASR-Coastal scheme.

The users have a right to take at least the recoverable freshwater volume. This volume is estimated by KWR each spring. The recovery rate is limited to 200 m³/h, which is 1 m³/h per hectare of greenhouse. This is the minimum guaranteed supply rate for each user. Again, the rates can be transferred from one user to the other.

Scientific results

Scientific reports & Peer reviewed papers

In February 2016, more than 8,000 m³ of high-quality irrigation water was infiltrated and successfully stored until last August. Based on the recovery of over 1,400 m³ of freshwater and monitoring of the stored freshwater body during the test cycle, a groundwater transport model was built. With this model, the further expansion of the ASR scheme was modelled, which showed that a viable scheme is within reach for the TOM.

• Zuurbier, K.G., 2017. Completed demonstration of the use of extensively treated wastewater for ASR Coastal. SUBSOL deliverable D2.5
• Zuurbier, K.G.,Van Dooren,T., Ros, S. 2018. Guide on using ASR-Coastal with treated wastewater for irrigation. SUBSOL deliverable D2.6
• Zuurbier, K.G., Ros, S, 2017. Aquifer storage and recovery van gezuiverd effluent Nieuw Prinsenland (Dinteloord).