The invention discloses a method for treating
paraquat wastewater at normal pressure. The method comprises the following steps: adding acid into the
paraquat wastewater to adjust the pH value to be 7.5-8.0, preparing a
medicine solution, adding the
medicine solution to stir so as to obtain a material liquid, centrifuging, combusting the centrifuged residues, feeding the centrifugate into a normal pressure kettle with an
ultraviolet lamp device of 100-5,000w, adding acid to adjust the pH value to be 3-4, adding a certain amount of
iron sulfate heptahydrate, stirring to dissolve, subsequently powering on the
ultraviolet lamp, dropping 30wt%
hydrogen peroxide, reacting for 0.1-1 hour at normal temperature after the dropping is accomplished, dropping
liquid ammonia till the pH value is 8, putting into a centrifugal
machine to
centrifuge so as to remove iron
cement, feeding the centrifugate into an
evaporation device to evaporate water which meets the
pollution discharge standards of
municipal sewage treatment plants and can be directly discharged, recycling and reusing the concentrated liquid, and obtaining a byproduct, namely, faint yellow
ammonium chloride. The method is rapid in
reaction speed, high in efficiency, high in performance cost ratio, low in investment and cost and simple in process.