Techno-Economic Evaluation of Iron and Aluminum Coagulants on Se(IV) Removal

Water

Kyriaki Kalaitzidou¹  Manassis Mitrakas¹  Loukas Bakouros¹ 

[1] Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;

关键词: tetravalent selenium se(iv);    fe-based coagulants;    pacl;    polluted waters;    cost estimation;   

DOI  :  10.3390/w12030672

来源: DOAJ

【 摘 要 】

Research on selenium pollution in natural waters is continuous and discouraging. In this study, coagulation/precipitation was applied with the use of Fe(II), Fe(III), and poly-aluminum chloride (PACl) salts for Se(IV) removal at concentration range 10−100 μg Se(IV)/L that is commonly found in drinking waters. Prehydrolyzed Fe(III)-FeCl₃ delivered the best uptake capacity (Q₁₀ = 8.9 mg Se(IV)/g Fe(III) at pH 6) at the residual concentration equal to the drinking water regulation limit of 10 μg/L. This was much higher than the efficiencies achieved when applying the other coagulants: i.e., Q₁₀ = 7.3 mg Se(IV)/g Fe³⁺-FeClSO₄, Q₁₀ = 6.4 mg Se(IV)/g prehydrolyzed Fe(III)-Fe₂(SO₄)₃ and 0.7 mg Se(IV)/g Al-PACl at pH 6, and Q₁₀ = 0.45 mg Se(IV)/g Fe(II) at pH 7.2. Comparing the different sources of Fe(III), it is apparent that Se(IV) uptake capacity is inhibited by the presence of SO₄^2- in crystal structure of prehydrolyzed Fe₂(SO₄)₃, while prehydrolyzed FeCl₃ favors Se(IV) uptake. Temperature effect data showed that coagulation/precipitation is exothermic. In techno-economic terms, the optimal conditions for Se(IV) removal are coagulation/precipitation at pH values lower than 7 using prehydrolyzed Fe(III)-FeCl₃, which provides a combination of minimum sludge production and lower operating cost.

【 授权许可】

Unknown