This study investigates the influence of the initial pH on the removal of reactive black 5 dye (RB5) from water using electrocoagulation (EC) reactor supplied with aluminium electrodes. The influence of the initial pH has been investigated by commencing several sets of continuous flow experiments at five different initial pH values (4, 5, 6, 7, and 8) keeping the current density, inter-electrodes distance, and the concentration of RB5 constant at 2 mA/cm2, 4 mm, and 25 mg/L, respectively. The obtained results showed that the removal efficiency increased gradually as the initial pH increased from 4 to 6 to reach its maximum level (96%) at the neutral range of pH, then it decreased to 74% as the initial pH increased to 8. This change of the removal efficiency with the initial pH could be attributed to the predominant species of aluminium coagulants, where in alkaline and acidic conditions; the prevailing species have low adsorption capacity for pollutants. While, in the neutral range of pH, the predominant species have high adsorption capacity for pollutants.

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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.

Water is vital to the survival of humans and all other life forms, yet many sources of freshwater are being contaminated due to pollution, significantly limiting freshwater availability, and threatening human existence. Nitrates and ammonium are common water contaminants whose concentrations in water have increased significantly due to the excessive use of fertilisers. High concentrations of such contaminants in water can lead to multiple health issues, and thus controlling the concentration levels of these pollutants in water grows into the main task for environmental scientists. A natural zeolite filter was employed in this study to minimise traces of contaminants in water. Samples of synthetic polluted water were prepared that contained 50 mg/L of each contaminant for the laboratory tests. Testing natural zeolite doses ranging from 1 to 5 g/L at various pH levels (between 3 and 10) showed that a zeolite filter significantly improved the water quality from the initial concentrations of each pollutant by between 10 and 50 mg/l. In particular, more than 93% of both contaminants (nitrate and ammonium) were removed by using a 5 g/L dose of zeolite in a neutral pH level range for 120 minutes.