Experimental design of wastewater treatment with electro-coagulation

Abstract

Purpose – The purpose of this paper is to investigate the batch treatment of pulp and paper mill wastewater using electro-coagulation (EC). Design/methodology/approach – Statistical experimental design was used to investigate the effect of initial pH, current density and temperature. Experiments were planned to obtain the maximum amount of information in the fewest number of runs. Minimum-maximum values of current density, initial pH, temperature of medium were selected as 9-25 mA/cm2, 5-9, 25-50°C, respectively. A total number of 20 experiments including eight factorial points, six axial points and six replicates in centre points were carried out and experimental data were collected. Optimum operating parameters were determined by evaluating experimental results in MATLAB 7.9®. Findings – According to the results, the optimum values of current density, initial pH and temperature of medium are determined as 14.12 mA/cm2, 8.22 and 34.21°C, respectively. Practical implications – Many researches about different techniques including physical, chemical and biological methods have been done on the subject of pulp and paper wastewater treatment. In physical and chemical processes low molecular weight compounds are not removed efficiently, also these methods are quite expensive. Electrochemical degradation has an advantage of removing even the smallest colloidal particles compared with traditional flocculation and coagulation. Originality/value – Complete removal of pollutants, less sludge generation, simple process design and easy operation are standard features of the EC and it comes forward as one of the promising techniques.

ELEKTROKOAGÜLASYON YÖNTEMİYLE KAĞIT ATIK SUYU ARITIMINDA pH KONTROLU

“…Bu çalışmada bulanıklık giderimi yönünden en düşük değer % 66,1 ile set noktası 11 seçilen pH kontrol uygulamasında görülmüştür. Daha önceki araştırıcıların rapor ettikleri, kağıt atık suyunun kontrolsuz gerçekleştirilen elektrokoagülasyonla arıtımından elde edilen deneysel veriler kullanılarak merkezi bileşik deney tasarım yöntemi ile bulanıklık giderim yüzdesi için elde edilen ikinci derece polinom tipi eşitlik (Camcioglu et al, 2014) bu çalışmada karşılaştırma maksadı ile kullanılmıştır. Bu eşitlikte başlangıç pH'ı 11'de sabit tutulmuş, akım yoğunluğu 9 mA/cm ile 25 mA/cm 2 arasında, sıcaklık 25 o C ile 50 o C arasında değiştirilerek bulanıklık giderimleri hesaplanmıştır.…”

“…Kağıt atık suyunun elektrokoagülasyon yöntemi ile kontrolsuz olarak gerçekleştiren arıtımında başlangıç pH'ının 0,1 M HCl ve 0,1 M NaOH kullanılarak 5 değerine ayarlanması sonucunda akım yoğunluğunun 9 mA/cm ile 25 mA/cm 2 arasında, sıcaklığın ise 25 o C ile 50 o C arasında değişim gösterdiği farklı koşullarda % bulanıklık gideriminin % 10,07 ile % 57,96 aralığında değiştiği deneysel verilerle ortaya konmuştur (Camcioglu et al, 2014). Bu çalışmada ise pH değeri elektrokoagülasyon boyunca 5'te kontrol altında tutularak bulanıklık gideriminde % 98,6 değerine ulaşılmıştır.…”

Applications of Combined Electrocoagulation and Electrooxidation Treatment to Industrial Wastewaters

“…As stated in Section 1, EC is a fast but incomplete process, while EOx is a complete but slow process; coupling the two processes proposes a functional hybrid. COD removal mechanism of a combined EC and EOx process can be summarized as follows: production of metal ions; hydrolysis of metal ions to generate metal hydroxides and/or polyhydroxides in appropriate pH; generation of bubbles of oxygen and hydrogen gases at the anode and the cathode, respectively, which provides the flotation of coagulated pollutants; destabilization of colloidal pollutants and trapping of destabilized colloidal particles to form flocks; removal of pollutants by precipitation [46]; formation of adsorbed hydroxyl radicals on anode surface [39]; degradation of organic pollutants by direct oxidation of adsorbed hydroxyl radicals; generation of indirect oxidizing agents such as chlorine, hypochlorite, and hydrogen peroxide near the anode; and electrochemical combustion of organic pollutants by indirect oxidizing agents [26].…”

Harvesting of microalgae: Overview of process options and their strengths and drawbacks

“…Electro-coagulation (EC) has been referred as one of the most e7ective method for reducing harvesting costs, as it avoids the use of ;occulants, uses small electricity amounts, is very fast and eCcient (Poelman et al, 1997;Matos et al, 2013;Pacheco et al, 2015). EC has been widely used for the treatment of wastewater (Camcioglu et al, 2014;Bukhari, 2008) and to improve the quality of the drinking water (Alfafara et al, 2002;Poelman et al, 1997). Publications show its eCciency for the removal of small colloidal particles, dyes (Alinsa6 et al, 2005), total suspended solids, chemical oxygen demand and turbidity (Inan et al, 2004).…”