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The effect of peracetic acid (PAA) on indicator bacteria in secondary sewage effluent has shown PAA to be a viable alternative to other biocides. The synergy between UV/PAA and UV/H2O2 in laboratory experiments and at a pilot plant fed by the secondary effluent of two civil wastewater treatment plant has been investigated. This experiment is part of a larger research project on advanced treatment for municipal wastewater reuse in agriculture. A very high level of disinfection is necessary because of Italy's strict limits on unrestricted wastewater reuse in agriculture (2 CFU Total Coliform/100 ml). We found out that a combined treatment is satisfactory and that it is more efficient when chemical products such as PAA or H2O2 are introduced before UV irradiation, taking advantage of the hydroxyl radicals formation due to photolysis. At a cost parity PAA/UV advanced oxidation process shows the same disinfectant action as H2O2/UV while at a dose (amount) and cost parity, PAA shows a significantly better disinfectant action than H2O2.

Olive oil production, one of the main agro-industries in Mediterranean countries, generates significant amounts of olive mill wastewaters (OMWs), which represent a serious environmental problem, because of their high organic load, the acidic pH and the presence of recalcitrant and toxic substances such as phenolic and lipidic compounds (up to several grams per litre). In Italy, traditional disposal on the soil is the most common way to discharge OMWs. This work is aimed at investigating the efficiency and feasibility of AOPs and biological processes for OMW treatment. Trials have been carried out on wastewaters taken from one of the largest three-phase mills of Italy, located in Quarrata (Tuscany), as well as on synthetic solutions. Ozone and Fenton's reagents applied both on OMWs and on phenolic synthetic solutions guaranteed polyphenol removal efficiency up to 95%. Aerobic biological treatment was performed in a batch reactor filled with raw OMWs (pH = 4.5, T = 30 degrees C) without biomass inoculum. A biomass rich of fungi, developed after about 30 days, was able to biodegrade phenolic compounds reaching a removal efficiency of 70%. Pretreatment of OMWs by means of oxidation increased their biological treatability.

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