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This experimental study concerns the elimination of fluoride from water using an electrocoagulation reactor having a variable flow direction in favour of increasing the electrolysing time, saving the reactor area, and water mixing. The detention time of the space-saver EC reactor (S-SECR) was measured and compared to the traditional reactors using an inert dye (red drain dye). Then, the influence of electrical current (1.5 ≤ δ ≤ 3.5 mA cm−2), pH of water (4 ≤ pH ≤ 10), and distance between electrodes (5 ≤ ϕ ≤ 15) on the defluoridation of water was analysed. The effect of the electrolysing activity on the electrodes' morphology was studied using scanning electron microscopy (SEM). Additionally, the operational cost was calculated. The results confirmed the removal of fluoride using S-SECR met the guideline of the World Health Organization (WHO) for fluoride levels in drinking water of ≤1.5 mg/L. S-SECR abated fluoride concentration from 20 mg/L to the WHO's guideline at δ, ϕ, pH, operational cost, and power consumption of 2.5 mA cm−2, 5 mm, 7, 0.346 USD m−3, and 5.03 kWh m−3, respectively. It was also found the S-SECR enhanced the detention time by 190% compared to the traditional reactors. The appearance of dents and irregularities on the surface of anodes in the SEM images proves the electrolysing process.

Phosphate is a common chemical element that resides extensively in the Earth’s crust, and its presence in water results in eutrophication of water. Therefore, many studies were devoted to study the ability of phosphate removal from water and wastewater using different treatment methods. Recent studies have suggested that filtration treatment techniques are effective for phosphate removal with one disadvantage which is the high cost of industrial filtration materials used. As a result, recent studies are concentrating on minimizing the operational costs of the filtration method by using cost-effective alternatives. This study is focusing on the efficiency of using the wastes of the iron industry (furnaces bottom ashes (FBAs)) for phosphates elimination from synthetic water. Several operational conditions which are detention times, FBAs doses, and phosphate concentrations, were studied to obtain the best conditions which ensure the best possible removal rate and a reasonable operational cost. The results indicated that FBAs are an efficient alternative for phosphate removal with an optimum removal rate of 88.9% with 31 min retention time, phosphate concentration of 5 mg/L, and 550 mg/L FBAs doses. The results obtained were used to construct a model with high reliability at R2 = 0.967.

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