Application of electrocoagulation method in wastwater treatment of stonslabindustry an‎d investigating the effect of chemical additives on efficiency an‎d process rate

1/1/1900 12:00:00 AM

Slab stone is one of the largest water consuming industries which, during the stone cutting an‎d finishing processes, produces a lot of wastewater with high pollution loads in terms of total suspended solids (TSS) an‎d turbidity. This further emphasizes the necessity for the adoption of efficient measures for wastewater treatment an‎d water reclamation. Common wastewater treatment methods, including sedimentation, chemical coagulation, an‎d filtration, are associated with certain technical an‎d environmental challenges, as a result of the production of high-volume residual sludge, potential chemical byproducts, an‎d limited efficacy. Accordingly, the current study applied an electrocoagulation method to wastewater treatment, using aluminum an‎d iron electrodes in a batch reactor. In the initial stage, preliminary experiments on the electrocoagulation process were reviewed based on the One Factor at a Time (OFAT) method, the effect of voltage parameters, the electrode spacing/distance, mixing time an‎d velocity, an‎d the pH. In the next stage, major parameters were selec‎ted for use in the response surface methodology (RSM) based on which, optimal conditions were determined. Meanwhile, the effects of adding polyacrylamide (PAM) an‎d the use of mechanical overhead stirrer on the performance an‎d efficiency of the process were investigated. The Fourier Transform Infrared Spectroscopy (FTIR) an‎d X-ray powder diffraction (XRD) techniques were used for the identification an‎d analysis of the composition of the generated flocs. Under optimal conditions (a voltage of 3.11, an electrode distance of 1 centimeter, a mixing time of 4.79 minutes, an‎d a pH of 8.51), the turbidity removal efficiency an‎d the TSS values were respectively 99.83% an‎d 99.53%. Meanwhile, the operational expense totaled 6.6 tomans per liter in a sedimentation time of 30 minutes. The adding of polyacrylamide (PAM) raised removal efficiency an‎d improved sedimentation so that under optimal conditions of a dosage of 2.99 milligrams per liter (mg/L), a voltage of 2.97, an‎d a mixing time of 3.79 minutes, the removal efficiency value was 99.82% with an operational expense of 6.03 tomans per liter. The use of the mechanical overhead stirrer led to increased homogenous mixing at the bottom of the reactor an‎d sedimentation of particles with no chemicals added, to bring the removal efficiency value to 99.91%. Thus, at a voltage of 2, a mixing time of 1 minute, an‎d a sedimentation time of 5 minutes, the operational expense was reduced to 0.57 tomans per liter. FTIR an‎d XRD analyses confirmed the formation of aluminum hydroxide (Al(OH)3) as a major coagulant in the process. Moreover, findings indicated that the electrocoagulation method, when combined with the use of an overhead stirrer an‎d a flocculant, proves to be an effective an‎d economical method for the treatment of the wastewater produced in the slab stone industry.

پساب صنعت اسلب‌سنگ , انعقادالكتريكي , روش پاسخ‌ سطح , كدورت

Electrocoagulation , Response Surface Methodology , Turbidity , Wastewater Produced in Slab Stone Industry

Mohammadreza Safari

Dr. Majid Hosseinzadeh