Study on Treatment Technology for Acidizing Wastewater in Henan Oil Field

An alkalinization—oxidation/adsorption—coagulation treating technology is suggested for hazardous reservoir acidizing wastewater(AWW).The AWW sample is taken from Henan oil field and has CODcr=4367 mg/L,which is composed of 70.4% inorganics and 29.6% organics.In the experimental study,the percentage removal(PR) of CODcr is taken as criterion and the proper dosages of chemical treating agents and the technologic parameters obtained are as follows.In alkalinization,proper dosage of Ca(OH)2 100 g/L,with which the pH of AWW rises from 1.0 to 11.5 and the CODcr lowers by 45.8%;in oxidation,proper dosage of H2O2(30% solution) 3 mL/L,of copper iron 4 g/L,and pH in range 3—4;in adsorption,proper dosage of active carbon(AC) 10 g/L,pH in range 4—5,and stirring time 60 min.In the further study by using orthogonality design method,optimal technologic parameters of oxidation/adsorption in combination are ascertained: dosage of H2O2 in solution 3 mL/L,of copper iron 4 g/L,and of AC 10 g/L,pH=4.5,and stirring time 80 min.For AWW sample alkalinized,treated by oxidation/adsorption and having CODcr=315 mg/L,coagulation by PAC at dosage 2.5 g/L as a last treating step gives a qualified purified water with following parameters: pH=7.5,CODcr=115 mg/L,or PR of CODcr=97.4%,SS content 4 mg/L(624 mg/L for original AWW sample),oil content 0.4 mg/L(1.41 mg/L),chromaticity 6 mg/L(110 mg/L),and Cl-concentration 198 mg/L(47341 mg/L),which fulfils the grade Ⅱ norms of state standard for effluent waste waters.