Implementation of a new modular facility to detoxify agro-wastewater polluted with neonicotinoid insecticides in farms by solar photocatalysis

Highlights: • Neonicotinoid insecticides from wastewater (WW) were removed by solar photocatalysis. • WW were produced in 3 farms from the washing of phytosanitary treatment equipment. • Different photocatalytic treatments in each farm were carried out. • Degradation was conducted using a new modular facility in farms, TiO₂ and Na₂S₂O₈. • Higher effectiveness was mainly obtained at low concentrations of pesticides. -- Abstract: As a consequence of phytosanitary treatments on crops a volume of agro-waste water containing pesticide residues from remnants and rinse of the treatment machinery is usually generated. These residues can become a danger to the environment and human health. Therefore, three pilot facility located in different farms were developed and used for wastewater detoxification containing four neonicotinoid insecticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) by means of heterogeneous photocatalysis (TiO₂ in tandem with Na₂S₂O₈) and natural sunlight. Previously, the catalyst load (300 mg L⁻¹) and oxidant concentration (300 mg L⁻¹) were optimized at lab-scale using a photoreactor. The remaining percentage of the insecticides were in the range 0–47% for thiamethoxam, 0.1–33% for imidacloprid, 2–66% for acetamiprid and 0.02–60% for thiacloprid of the total initial mass. The observed differences for each insecticide in same farm could be due to total initial concentration of pollutant due to others pesticides (non-neonicotinoid insecticides) used in the farms, and the different physical-chemicals characteristics of the water used to fill and wash of treatment equipment. The results obtained have demonstrated a cost-effective viable alternative to degrade the neonicotinoids insecticide residues contained in these agro-wastewater, with an innovative and energetically efficient facility placed in the farms.