Non-conventional municipal wastewater treatment based on surface filtration for the production of water suitable for irrigation.

In the framework of the Euro-India project Water4Crops (call FP7 KBBE 2012-6, contract n. 311933) long term pilot scale tests were performed for evaluating the suitability of treated municipal wastewater effluents for irrigation. Two pilot plants were operated in order to evaluate the effectiveness of two different technologies and the quality of produced effluents with respect to national water quality standards for reuse in agriculture. Both the tested technologies were based on the coupling of biological processes and surface filtration, and each of the two pilots was made of: 1) a process based on surface filtration which treated a continuous flow; 2) a UV disinfection system treating only the effluent fraction used for irrigation, and operated on demand. The first plant was based on the technology IFAS-MBR (Integrated Fixed-film Activated Sludge - Membrane BioReactor), and treated raw sewage after preliminary screening. The second pilot was based on the technology FDG (Filtro a Dischi a Gravità, Gravity Disk Filter) and treated the secondary effluent. The effluents produced by the pilots were accumulated into storage tanks and submitted to on-demand UV disinfection (i.e. operated when irrigation was switched on). Results showed the effectiveness of both tested technologies in producing effluents suitable for reuse in agriculture and complying with the local standards.