METHOD OF DETERMINING WORKING DOSES OF COAGULANT IN NATURAL WATER TREATMENT PROCESSES Russian patent published in 2013 - IPC C02F1/00 

FIELD: chemistry.

SUBSTANCE: invention relates to determination of coagulant doses during reactant treatment of natural water using aluminium-containing coagulants in order to reduce turbidity, colour index, oxidation susceptibility and residual aluminium. The method includes conducting test coagulation to obtain experimental data, statistical processing of said data and, based on the results, obtaining a calculation relationship of the type: D_k=K¹M^αT^βPO^γA^φ _resS_k (1), where D_k is the working (required) dose of the aluminium-containing coagulant, mg/l; M is turbidity of the starting water, mg/dm³; T is the colour index of the starting water, deg; PO is the permanganate value, mgO₂/dm³; Aℓ_res is residual aluminium in settled water, mg/dm³; S_k is complex coagulation capacity of the colloidal suspension determined according (2). $$S_k=A\frac{t^{\alpha }S{A}^{\beta }{С}^{\gamma }}{{\left(-\zeta \right)}^n{\left(-Eh\right)}^m},\left(2\right),$$ where t is temperature, °C; SA is alcalinity, mg-eq/l; S is total salt content, mg/l; (-ξ) is negative zeta potential, mBV; (-Eh) is the negative redox potential value, mV; A, α, β γ, n, m are constants and coefficients of regression, from which the optimum coagulant dose is determined based on the obtained minimum values of M, T, PO and Aℓ_res in water settled for 30 minutes after coagulation with reagents with dose range from 0.2 to 10 mg/l on Aℓ₂O₃ for M≤100 mg/dm³ and T≤100 deg, and from 10 to 50 mg/l for large values of said ingredients and concentration of working solutions of the coagulant from 1.5 to 5%.

EFFECT: enabling rapid and more accurate determination of required coagulant doses during change in stability of colloidal impurities and quality of treated water in a water source without repeating test coagulation of the source water every time.

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