The increasing water stress, and associated rising water prices, emphasize the need for increased reuse of process or waste water during the processing of vegetables and potatoes. This is not entirely without risk. When reused, pesticides, the so-called plant protection products (PPP), can accumulate in the process water, causing cross-contamination to, for example, other or the same type of crops. The WaMIP project examined, among other things, the process and waste water (before, during and after conventional water treatment) that comes into contact with vegetables and potatoes. The first results show that PPP are not sufficiently removed from the treated water by the current (conventional) water purification plants. This results in the following potential problems:
(i) Problem with discharge, as multiple exceedances are noted (cf. VLAREM II) with possible negative effects on aquatic ecosystems and additional levies and fines for the companies;
(ii) Problem with reuse, during the processing process the regulations described in Royal Decree 14/01/2002 and EU regulations 98/83 / EC are not met. This leads to a possible transfer of PPP to the crops from the process water. Unexpected not insignificant amounts of PPP can return to the crops.
The use of an ozone-based treatment, whether or not in combination with activated carbon, has already been shown to efficiently remove similar components (eg pharmaceutical residues and / or pesticides) from eg conventionally purified domestic wastewater. However, there are still many unknowns before a successful application can be guaranteed. After all, the target components (PPP) are only a limited part of the entire water matrix. Specifically for the vegetable and potato processing sector, however, there is insufficient knowledge about (i) the implementation (efficiency) and (ii) the influence on the entire water matrix (including organic matter) of the proposed process waters.
The proposed ozone-based water treatment, whether or not combined with activated carbon, can be switched after the current usual wastewater treatment plant. This combination should result in (i) a purified waste water that meets the proposed discharge conditions and is less environmentally harmful from an ecotoxicological perspective, and (ii) a physicochemical (PPP under the drinking water standard) and microbially safe (reusable) process water. Both goals need to be achieved in a cost efficient manner. It will also be investigated how this can be incorporated into the HACCP plan and self-checking system of the respective companies.
The following concrete objectives have been formulated: (i) to gain insight into the current water characteristics with regard to variability, both over time and across the companies, and the impact thereof on the proposed treatment technique (s), (ii) to identify the risk of water characteristics by the formation of PPP transformation and / or by-products, (iii) the assessment of possible parameters that can be monitored online for monitoring and controlling the removal of PPP, (iv) obtaining a guideline based on an optimized and validated treatment strategy, for both the correct and ecotoxicologically responsible discharge of treated wastewater and the reuse of treated wastewater as process water 'fit-for-purpose'.
This project focuses on water from the vegetable and potato processing sector. Particularly for the frozen food industry but also fresh cut plants (4th gamme), other food sectors (e.g. meat sector) that may have similar or similar problems will also be able to use the obtained results.