Abstract: Photovoltaic (PV) energy systems are one of the best renewable energy technologies due to the high green energy productivity. Here PV system was combined with the wastewater treatment plants (WWTPs) which are usually designed separately. For this, a methodology was proposed by providing some steps to evaluate the peck power of PVs to reduce the energy consumptions of aeration tanks in WWTPs. New analytical equations and parameters, based on the air temperatures, solar irradiations, biological kinetics, dissolved oxygens, mechanical oxygenations, were defined. In particular, the key parameter was the air temperature variation that represent a good reference temperature in the oxidation tanks.

The oxidation tanks consume about 30% of the total cost for a WWTP. For a small WWTP this cost can increase since the temperature changes in function of the season variation, therefore there is a peak in function of the quantity of oxidation, thus energy consumption, which is high in the summer season. This is because, when the temperature increases, the oxygen decreases. Also, by curves in terms of solar radiation vs. temperature, it is shown that the curve trend is like a PV system and therefore it could be possible to well design the PV system with the WWTPs.

Results show that if the air temperature curve increases, the energy consumption of oxidation blowers increase; in this way the PV design is in favour of safety without overestimate the design parameters. Also, results show that the average trend of the energy consumption of aeration systems reach a value of 10-15% (covering part of 30%) by a temperature of 20-25 °C.

This study will support the sector in making decision over PV investments, helping wastewater utilities to consider sustainable management practices. In this sense, a further contribute to develop the integration of renewable energy sources, combined with wastewater sectors, is encouraged. This purpose is consistent with the goal 7 of the 2030 Agenda for Sustainable Development to “ensure access to affordable, reliable, sustainable and modern energy for all”.