Study On Pretreatment Methods And Effects Of Oil,Phenol And Ammonia In Coal Chemical Wastewater

The amount of waste water produced in the coal chemical process is large and the water quality is complex.It is a typical industrial waste water that is difficult to treat.At present,the biochemical treatment systems of the domestic and foreign coal chemical wastewater generally have practical problems such as destitute framework operation solidness and troublesome to meet release guidelines,which extremely influence the feasible and sound advancement of the coal chemical industry.The most reason is the undesirable impact of wastewater pretreatment,which makes the consequent biochemical treatment troublesome to operate normally.In response to the above problems,this research focuses on the treatment methods and effects of oil,phenol,and ammonia in wastewater and conducts field tests.It is expected that a coal chemical wastewater pretreatment method with low investment cost,simple operation and stable treatment effect can be found.It is of great practical significance to provide a method for the recovery of resource materials and the thorough harmless treatment of coal chemical wastewater.The main findings are as follows:(1)The quality characteristics of raw water are analyzed in Shenmu Xinyi Coal Chemical Industry and the on-site production wastewater was used as the test sample.The content of the oil in the water was 710-820 mg/L.The content of the phenol was1480-1880 mg/L.The content of the ammonia nitrogen was 12500-18000 mg/L.The content of the COD was 12,000-16000 mg/L and the turbidity was 127-128 NTU;The analysis of the existing state of the oil in the coal chemical wastewater showed that the oil particle size that was less than 0.22?m accounted for 72.70%.(2)The high-concentration oil and phenol wastewater at the on-site production was primarily investigated by solvent extraction technology.The results showed that beneath the conditions of the room temperature being about 25 degrees centigrade,the p H value being the crude water value of coal chemical wastewater,the ratio being 15:1,synergistic extractant MIBK and butyl acetate,the oil and phenol in the effluent could be reduced from 823.50 mg/L and 1827.07 mg/L to 65.69 mg/L and 239.91 mg/L respectively,and the removal rates were 92.02%and 86.87%respectively.(3)High-concentration oil and phenol in coal chemical wastewater was treated using macroporous resin.The results showed that the removal rates of oil,phenol and COD could reach 87.48%,88.62%and 64.24%,respectively,beneath the conditions of normal room temperature,p H of raw water and the influent flow rate of 8 BV/h.SEM and FTIR analysis showed that the resin had the good adsorption properties and could adsorb phenols.The saturated resin was regenerated by combining Na OH solution with ethanol,which could realize the stable operation of adsorption-regeneration and the recycling of resin.(4)After oil and phenol removal,the coal chemical wastewater with high concentration of ammonia nitrogen was treated by air stripping process in this study.The content of the effluent ammonia nitrogen could be reduced from 15960 mg/L to1390.57 mg/L by adjusting the p H value of the wastewater to 11,controlling the temperature of the system to 60?,adjusting the intake air flow rate to 4 LPM and stripping for 1 h,and its removal rate could reach 91.29%.(5)In order to meet the water quality requirements of subsequent biochemical treatment,Fenton oxidation treatment was adopted for the wastewater after the pretreatment of oil,phenol and ammonia.Under the conditions of normal temperature,p H of 3.5,Fe SO₄·7H₂0 addition of 4 g/L and H₂O₂addition of 36.727 m L/L,the oil,phenol and COD in coal chemical wastewater could decrease from 210.62 mg/L,839.86mg/L and 7617.20 mg/L to 4.04 mg/L,1.05 mg/L and 1498.40 mg/L,respectively.(6)Coal chemical industry wastewater was preprocessed test in laboratory experiments through comprehensive treatment technique 1(raw water-solvent extraction-ammonia nitrogen to remove-Fenton oxidation)and comprehensive treatment 2(raw water-resin adsorption-ammonia nitrogen to remove-Fenton oxidation),respectively.The results showed that:the comprehensive process 1 had a high removal rate of oil and phenol and low turbidity of the effluent,but this process had problems such as high extractant loss rate and high energy consumption,which ultimately led to high water treatment costs and complicated operations and so on.For the comprehensive treatment process 2,the effluent oil,phenol,ammonia nitrogen,COD,UV254 and turbidity were 2.83 mg/L,1.01 mg/L,862.23 mg/L,977.29 mg/L,0.10 and 4.14 NTU,respectively.No other pollutants were introduced into the this process,and the effect of resin adsorption-regeneration was relatively stable.(7)The comprehensive treatment process 2 was used to operate field pretreatment test for coal chemical wastewater with a treatment scale of 0.5 t/h.The results showed that the effluent oil,phenol,COD and ammonia nitrogen could be reduced to 6.31 mg/L,8.89 mg/L,1624.95 mg/L and 3519.39 mg/L,respectively.The field treatment of effluent was poorer laboratory,especially ammonia nitrogen,which was mainly related to the large amount of suspended solids,the low temperature of raw water,and limited field conditions.However,the effluent water quality except ammonia nitrogen could meet the requirements of biochemical treatment of influent water quality,this process could be used as an optional process for the pretreatment of coal chemical wastewater.