Journal of South China University of Technology (Natural Science Edition) ›› 2017, Vol. 45 ›› Issue (6): 139-144.doi: 10.3969/j.issn.1000-565X.2017.06.021

• Environmental Science & Technology • Previous Articles    

Experimental Investigation into Removal of Soluble Silicate in Groundwater by Using Compound Coagulants

TAO Hui1,2,3 LAI Lian-hua1,2 CHEN Qing3 BAI Xin-zheng3   

  1. 1.Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of the Ministry of Education，Hohai University,Nanjing 210098,Jiangsu,China; 2.College of Environment,Hohai University,Nanjing 210098,Jiangsu,China; 3.Suzhou Litree Water Purification Technology Co.,Ltd.,Suzhou 215152,Jiangsu,China
  • Received:2016-09-29 Revised:2016-12-21 Online:2017-06-25 Published:2017-05-02
  • Contact: 陶辉(1981-)，男，副教授，主要从事饮用水处理研究． E-mail:taohui@hhu.edu.cn
  • About author:陶辉(1981-)，男，副教授，主要从事饮用水处理研究．
  • Supported by:

    Supported by the Found of Major Science and Technology Program for Water Pollution Control and Treatment (2014ZX07405) and the Found of“Double Creation Plan”in Jiangsu Province

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Abstract:

In order to effectively remove the soluble silicate in water,by taking the groundwater with a soluble sili- cate content of 50 ～60mg/L as the research objective,coagulation experiments for the soluble silicate removal by using different compound coagulants were performed.The results show that (1) when the dosage of Ca(OH)2 is 450mg/L,the removal of soluble silicate and the turbidity reaches 51.16% and 74. 8%,respectively; (2) with the increase of Ca(OH)2 dosage (more than 450mg/L),the removal of soluble silicate slightly increases while the pH value of the effluent greatly increases,too; (3) FeCl3 has a poor removal on soluble silicate (less than 12. 55%) but has an advantage in turbidity control; (4) MgO possesses poor efficiency for both soluble silicate re- moval (less than 14. 53%) and turbidity control,and the optimal MgO dosage is 400mg/L; (5) the compound of FeCl3 and Ca(OH)2 possesses good performance on both soluble silicate removal and turbidity control,more than 60% of soluble silicate is removed and the effluent turbidity is less than 0. 65NTU; (6) the compound of FeCl3 and MgO also possesses good performance on both soluble silicate removal and turbidity control,more than 75% of solu- ble silicate is removed; (7) the compound of Ca(OH)2 and MgO results in a soluble silicate removal up to 73. 76%,which is relatively less than that contributed by Ca(OH)2 only (81. 41%); and (8) among the three a- bove-mentioned compound approaches,the compound of FeCl3 and MgO with a Fe3+ dosage of 16. 8 mg/L and a MgO dosage of 500mg/L is the best because it results in a soluble silicate removal of 76. 67% and an effluent tur- bidity of 0. 83NTU,and because it helps to obtain effluent with the lowest pH value,which saves the acid added in the later process.

Key words: groundwater, soluble silicate, coagulation, compound coagulant