Implementation of purification equipment for removal of plant protection products from horticultural discharge water

Surface waters in Dutch agricultural and horticultural areas do not meet the requirements of the European Water Framework Directive for good chemical and ecological water quality. Emission of nutrients and plant protection products (PPPs) from agricultural activity contributes to this. The Dutch government issued emission standards for nitrogen, evolving to zero discharge in 2027 for all greenhouse crops. However, to reduce the leaching of PPPs to surface and ground waters on the short-term, additional legislation came into force January 1, 2018. This regulation obliges Dutch growers to use purification equipment for the removal of 95% plant protection products (PPPs) when discharging drain water to sewage or surface water. This stimulates growers to look critically at opportunities to reduce the amount of discharge water, thus lowering the investment and operational costs of purification equipment. In this article, we describe the implementation of the obligated purification for different types of cultivation systems, including the development of an approval protocol for purification equipment. Depending on the amount of discharged water and company size, growers will choose between either applying an installation at the company level or cleaning the water cooperatively with a group of locally located companies. Another option, especially suitable for infrequent small amounts of discharge water, is rental of a mobile purification unit. In any of these three cases, the growers must use an approved installation. The installation and the applied technical specifications (for example ozone dosage) need to be tested with so-called Standardised Water following a strict protocol. An installation is approved by a governmental committee if tested correctly with a purification efficacy of 95% for each of the 11 active ingredients of PPPs in Standardised Water.