Samenvatting

In the Netherlands, advancing environmental requirements and emerging competition from foreign countries are forcing greenhouse companies to optimize and innovate continuously. Due to this optimizing and innovating greenhouses have a high water recycling rate nowadays. However, due to various reasons water is still being discharged resulting in overruns of the water quality standards. In the near future greenhouse companies are forced by legislation imposed by the Dutch government to treat their waste water before discharging.
Plant protection products (PPPs) present in the waste water of the greenhouse companies are usually poorly biodegradable and therefore conventional on-site biological treatment is not sensible for meeting the (future) legislation regarding discharging wastewater. For the reduction or removal of PPPs from the waste water of greenhouses more advanced treatment techniques are required. Advanced oxidation processes (AOPs) offer a promising perspective for the reduction or removal of PPPs and persistent substances from waste water.
In this study the (combinations of) AOP techniques ozone, ozone/low pressure ultraviolet and ozone/low pressure ultraviolet/ultrasound are tested. The waste water used in this study derived from a substrate tomato grower. The test setup that was used was a recirculation system at which the water was treated batch wise.
On the basis of the results in this study it can be concluded that the degradation of the active ingredients of the PPPs present in the waste water is incredibly good with the used AOP techniques. A removal rate of more than 99,9% of the PPPs and a TOC (Total Organic Carbon) degradation of 30% at an ozone dose of 1,55 gram ozone per gram COD was achieved for the ozone/low pressure ultraviolet/ ultrasound technique.
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