A zero-discharge process for nickel-containing heavy metal wastewater

Abstract

The invention discloses a zero discharging process for nickeliferous heavy metal wastewater. The zero discharging process comprises the steps of reacting water to be treated with heavy metal capture agent, adding flocculant for flocculating settling, performing sand leaching, carbon filtering, secondary carbon filtering and ultrafiltration, and reducing turbidity, SDI and heavy metal content of inlet water in the reverse osmosis processes; entering the first reverse osmosis process and the second reverse osmosis process, recycling water produced, performing secondary flocculating settling on rejected water and ultrafiltration rejected water, and performing the tertiary reverse osmosis process; dividing the final reverse osmosis rejected water into two parts, wherein one part flows back to be led to the secondary flocculating settling to be retreated, and the other part is led to an after-treatment process. By means of the backflow design, the discharge amount of the final rejected water can be lowered, and the total produced water recovery rate is improved; the recovery rate of produced water in each reverse osmosis process is controlled to be reduced, sewage blocking of the reverse osmosis system can be prevented, the overall operation of the system is stabilized, and finally, the recovery rate of 90% or more of waste water is achieve stably, and real zero discharging is achieved.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to a process for zero discharge of nickel-containing heavy metal wastewater. Background technique [0002] Nickel-containing wastewater is difficult to reuse due to its large water volume and high difficulty in treatment. The existing recycling method is mainly to carry out advanced oxidation to break the network of the collected heavy metal wastewater. This method needs to add a large amount of chemicals. Add polybasic aluminum chloride and polyacrylamide to make the generated hydroxide precipitate and react into large particles, which is beneficial to the precipitation removal. After coagulation and sedimentation, the pH of the effluent is adjusted to facilitate the subsequent ultrafiltration and reverse osmosis systems. After the pH adjustment, the effluent enters the sand filter and carbon filter system to remove fine particles in the wastewater, which is b...

AI Technical Summary

Problems solved by technology

It can be seen from the above that the existing zero-discharge process of heavy metal wastewater requires the addition of a large amount of chemicals, which is not conducive to the subsequent ultrafiltration and reverse osmosis systems, and also causes high conductivity of the effluent, which is not conducive to the reuse of produced water. The recovery rate of water is low, generally not more than 70%, the reverse osmosis membrane is seriously fouled, and it is difficult to clean, so the system cannot be operated stably for a long time

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