Study On Process In The Advanced Treatment Of Municipal Sewage Used For Oilfield Reinjection Water

Da Qing oilfie lds is the place of important energy exploitation,because theprocess of oil field exploitation needs to comple ment plenty of water as injectionwater, Daqing Sazhong oil fie ld injection water quantity is between3.78×10~4and5.21×10~4m~3/d.Using surface wastewater nearby after anvanced treatment asreinjection water first,and comple menting municipal network water else.It’s saidthat Sazhong oil field needs to comp lement munic ipal network water quantity is2.210~4～2.4810~4m~3/d,which wastes water resources and makes running costhigher.Taking other water source as reinjection water instead of municipal networkwater.Therefore, with the growing shortage of water in view of the current Sazhongoilfield region, the project takes Daqing City sewage treatment plant secondaryeffluent as the research object for us ing reinjection water after advancedtreatment.First, after water quality analysis, solids,sulfate-reducing bacteria,saprophytic bacteria and iron bacteria of secondary effluent were substandard,whichbelonged carbonate-sodium type,had no tend to scaling.Then, to study the feasibility of advanced treatment, static coagulation testand sma ll-scale continuous test were took. Determine fungicides and coagulantdosing type, dosage, etc., as well asthe compatibility with oilfie ld produced waterafter advanced treatment were evaluated.The results showed that the tests werefeasible and had great removal effects on water. The optimum dosage of flocculant,coagulant and fungicides are30mg/L,3mg/L and50mg/L, respectively. Goodcompatibility of two kinds of sewage,it can be used as oil field reinjection water.Finally,to determine the operating parameters,in the pilot phase,after therunning and debugging of the"coagulation-air floatation-filtering"four combinationsof process and sandflo filter process, combined with economic benefits generatedby different processes, the fina l process was recommended. The results showed thatall of five processes after running can reach the secondary effluent water standards,combined with the process operating costs,it wasdeterminedthat the optimal processwas the single-stage bila yer filtration process,after advanced treatment,soilds was2.48mg/L, sulfides was0.751μ m,the quantities of flocculant, coagulant andfungicides were30cell/mL,600cell/mL and3cell/mL, respectively. Running cost is0.85yuan/m~3, the process can produce annually45,955,000yuan economicbenefits.