Reverse osmosis pretreatment deep oil-removal process for cold rolling oily wastewater

Abstract

The invention discloses a reverse osmosis pretreatment deep oil-removal process for cold rolling oily wastewater, which comprises the following steps of: (1) before the cold rolling oily wastewater enters a chemical film dipping filter, adding sodium hypochlorite with the volume concentration of 8-12ppm, basic aluminum chloride with the volume concentration of 2-4ppm and anionic polyacrylamide with the volume concentration of 0.05-.-0.2ppm into the cold rolling oily wastewater; (2) intercepting the flocculated cold rolling oily wastewater by using a multi-medium filter, controlling the filtering speed to be 4-6m / s, and controlling a silt density index (SDI) to be less than 3; and (3) allowing the pretreated cold rolling oily wastewater to enter a filter with a chemical film dipping filter element, and controlling the flux value of the filter element to be 0.1-0.4m<3> / m<2>s.

Description

technical field [0001] The invention relates to a treatment process for oily waste water from cold rolling, in particular to a deep oil removal process for reverse osmosis pretreatment. Background technique [0002] After biochemical treatment, oily wastewater from cold rolling generally has a relatively high salt content, and desalination treatment is required to meet the quality requirements of reused water. Reverse osmosis is a traditional classic desalination process, but it is sensitive to trace oil in raw water. The oil content after pretreatment must be kept below 1ppm, otherwise it will lead to rapid fouling of the reverse osmosis membrane, frequent chemical cleaning, and system failure. Stable operation, the life of the membrane is shortened accordingly. [0003] After the biochemical treatment of oily wastewater from cold rolling, it still contains 1-5ppm of trace oil before entering the reverse osmosis device after a number of pretreatment measures. Since the wa...

AI Technical Summary

Problems solved by technology

Since the wastewater contains a certain amount of colloids and dissolved organic and inorganic substances, the activated carbon adsorption process will be used for treatment, and the adsorption material will soon reach saturation (activated carbon, etc. are hydrophilic broad-spectrum adsorbents, which absorb oil and also adsorb organic substances. , inorganic substances and water), it is not suitable for actual production; the trace oil remaining in the wastewater is close to the dissolved state (1-100nm), if microfiltration, ultrafiltration and other process equipment are used, not only the price is expensive, the process is complicated, but also cannot meet the standard stably ; In addition, the traditional chemical method of oil removal, such as chemical dosing, air flotation, filtration and other processes, the control accuracy is not high, and the purpose of precision oil removal cannot be achieved

[0004] All in all, there is no ideal method for deep oil removal of oily wastewater from cold rolling by reverse osmosis pretreatment