Magnetic Flocculation Technology for Copper and Zinc Ions Removal from the Tin Smelting Wastewater

Abstract

Magnetic flocculation technology was investigated for the removal of copper and zinc ions from simulated tin smelting wastewater, and the effects of magnetic powder dosage, flocculant dosage, and pH on the removal of copper and zinc ions were estimated. The results show that the effluent quality is poor with magnetic powder, PAC and PAM separately dosed, but when magnetic powder is combined with PAC or PAM, the excellent effluent quality is obtained with the removal rate of the copper and zinc ions of more than 90% and 70% respectively. In addition, under the condition of magnetic powder dosage of 30g/L and PAC dosage of 60mg/L, pH show more significant effect on zinc ions than copper ions with pH increased from 5 to 10, and the removal rate of zinc ions increase by about 24%, while the removal rate of copper ions only increase by about 2.5%. Compared with the system with single metal ion, the coexistent ion system has excellent heavy metal removal efficiency, namely the copper ions removal rate increase by 3.42%, and the zinc ions removal rate increase by 0.46%. Moreover, magnetic flocculation technology presents the characteristics of shorter time of flocculation and sedimentation, smaller volume of the flocs and faster separation velocity.

Development of a Short-Cut Combined Magnetic Coagulation–Sequence Batch Membrane Bioreactor for Swine Wastewater Treatment

“…Urine is the primary source of ammonia nitrogen in swine wastewater, and the organic matter comes from residual feces. In the MC process, SS in the wastewater used the magnetic species as the core to form flocs (alum flowers), and flocs were settled with the gravitational force [ 23 ]. On the other hand, as an inorganic polymer, PAC could hydrolyze and polymerize to form various aluminum hydroxyl compounds.…”

“…Magnetic adsorption and aggregation make the magnetic coagulation process more effective than conventional coagulation, improving the structure and strength of the flocs, thereby increasing the efficiency of solid–liquid separation and achieving sludge reduction [ 19 ] and removing suspended particles and colloidal substances in wastewater, thus reducing the chemical agent consumption and improving the removal efficiency [ 21 ]. As a cost-effective pre-treatment process, magnetic coagulation is being paid more and more attention, and it has been widely applied in high-strength wastewater treatment with high removal efficiencies of COD and TP [ 19 , 22 ] due to its effective removal of SS, COD, phosphate, and TP, which could mitigate the organic loading rate and improve the treatment performance for subsequent biological wastewater treatment processes [ 22 , 23 ].…”

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“…Since the best pH is 6.5 and 7.5 according to the results of the first set, thus it was decided to take the average value (7) to determine the best alum dose at this average value of pH. It was found that 120 mg/L of alum gives the highest removal efficiency (Fig.…”

“…Various improvements are introduced to the coagulationflocculation process, such as using natural or synthetic polymers as a flocculant aids to strengthen flocs, employing another technology of separation with the coagulation-flocculation process, like magnetic flocculation. Its principle is adding particles of a higher magnetic susceptibility into a conventional coagulationflocculation process to enhance the flocculation velocity and form flocs of high density to settle quickly [7]. It combines a traditional flocculation and a magnetic separation in one process exhibiting a quick, simple, energyefficient, and cost effective advantages [8].…”