The invention discloses a method adopting a combined technology of pre-oxidation and coagulating
sedimentation to process
wastewater containing
thallium and
ammonia-
nitrogen. According to the method, a
sodium hypochlorite oxidizing agent is added into a
wastewater collecting tank so as to oxidize
metal ions in
wastewater, the monovalent
thallium is fully oxidized into trivalent
thallium, monovalent thallium is converted into complex under the effect of strong oxidant, and at the same time, the
nitrogen in
ammonia-
nitrogen is degraded and removed in the form of
nitrogen gas. After pre-oxidation, the wastewater is lifted to an integral
processing facility through a self-sucking pump;
ferrous sulfate and poly aluminum
chloride (PAC) are added to form alumen ustum flocculus in a
precipitation unit, the precipitate is wrapped, the thallium complex is adsorbed, then quicklime is added to adjust the solution to an alkaline environment; in the alkaline environment, Fe<3+>, Al<3+>, and
prepolymer products thereof carry out
hydrolysis quickly to form Fe(OH)3 flocculus and Al(OH)3 flocculus; before the flocculus becomes big, the adsorption sites on the surface of flocculus form covalent bonds with Ti<3+>, the flocculus becomes bigger and bigger very quickly and goes on absorbing Ti<3+> in water; at the same time, Ti<3+>, Fe<3+>, Al<3+>, Zn<2+>, lead, and
cadmium carry out co-
precipitation reactions, and thus the heavy
metal ions in water are removed.