Effect of Slurry Aeration on Coagulation: An Application of Irregular Factorial Design Analysis

Year 2018, , 445 - 453, 28.12.2018

Mustafa Çırak

https://doi.org/10.17798/bitlisfen.428215

Abstract

The effect of the aeration on the coagulation of a bentonite suspension was tested in this study. The experimental
runs for this coagulation work was formed with the help of the irregular factorial design. Based on this irregular
fractional design, a statistical model (R2 = 92.65%; p-value<0.05) was computed to interpret the main effects and
interactions of the independent parameters: pH, aeration, and the Al-coagulant. The suspension pH was determined
as the most effective parameter in this system since the degree of the hydrolyses of aluminium directly varies as a
function of pH. Therefore, the increase in the suspension pH resulted in the higher sediment volumes whereas the
minimum sediment volume was obtained at pH 5. Furthermore, the interaction effect of the product: pHxaeration
in the statistical model was very critical for the performance of the process. Especially, at acidic pH levels, the
aeration adversely affected the sediment formation after the coagulation. 3-D response surfaces of the estimated
model also showed that the maximum amount of the Al-coagulant should be added at pH 5 and no aeration should
be applied for the minimization of the sediment volume. 

Keywords

Coagulation, DOE, Aeration, clay, colloid, suspension

Süspansiyon İçerisindeki Hava Kabarcıklarının Koagülasyon Performansı Üzerindeki Etkisi: Faktöriyal Dizayn Analizi Uygulaması

Abstract

Bu çalışmada, bentonite süspansiyonunun koagülasyonu esnasında sisteme verilen hava kabarcıklarının
fizikokimyasal süreç üzerindeki etkileri incelenmiştir. Koagülasyon çalışması için gerekli deney seti, istatistiksel
bir teknik olan fraksiyonel dizayn yöntemi ile oluşturulmuştur. Bu yöntem ile elde edilen istatistiksel model (R2
= 92.65%; p-value<0.05) parametrelerin (pH, havalandırma ve Al-koagülant) sistem üzerindeki temel etkilerinin
ve etklileşimlerinin belirlenmesinde ve yorumlanmasında kullanılmıştır. Sonuç olarak, alüminyum iyonlarının
hidrolizinin temel olarak pH faktörü ile değişmesi sebebi ile süspansiyon pH’ının performans açısından en etkili
bağımsız değişken olduğu görülmüştür. pH seviyesinin yükseltilmesi daha fazla çamur hacminin oluşmasına sebep
olurken en düşük çökelen katı hacmi pH 5 değerinde elde edilmiştir. Ek olarak, istatistiksel eşitlikteki pHxhava
etkileşiminin sistem performansı açısından kritik öneme sahip olduğu gözlemlenmiştir. Özellikle asidik pH
seviyelerinde hava kabarcıkları koagülasyon performansını olumsuz etkilemiştir. İstatistiksel modele ait 3-Boyutlu
etki yüzeyleri incelendiğinde ise koagülasyon sonrası elde edilen çamur hacminin minimize edilebilmesi için
maksimum Al-koagülantı pH 5 seviyelerinde eklenmesi gerekliliği tespit edilmiştir. Süspansiyon içerisindeki hava
kabarcıklarının ise flok oluşumunu engellediği ve optimum koagülasyon performansı için uygun bir parameter
olmadığı sonucuna varılmıştır. 

Keywords

Koagülasyon, DOE, DOE, havalandırma, kil, kolloid, süspansiyon

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