Enzymatic Bioregeneration of Activated Carbon by Laccase

Özgür Aktaş; Zeynep Merve Tiryaki; Işık Çoban

Makale detayları

Enzymatic Bioregeneration of Activated Carbon by Laccase

Yazarlar:

Özgür Aktaş | Zeynep Merve Tiryaki | Işık Çoban

Yayıncı:

Marmara University

Ana Başlıklar:

Çevre Yönetimi (Diğer)

Dergi:

International Journal of Advances in Engineering and Pure Sciences Vol.36 Issue 2, pp.160-172

Belge Tipi:

Makale

Yayın Tarihi:

1/2024

Belge Dili:

İngilizce

Document ID (Org No.):

2001319787

pISSN:

2636-8277

Anahtar kelimeler:

Özet:

 Activated carbon is widely used in combination with biological treatment systems for the treatment of organic compounds, which are refractory or toxic in conventional biological treatment systems. In these systems, compounds adsorbed on activated carbon may desorb within time due to a concentration gradient between adsorbent and the bulk liquid caused by the biodegradation of substrates in the liquid phase by microorganisms. The desorbed compounds are further biodegraded by microorganisms. This mechanism is called bioregeneration of activated carbon. Previous studies showed that bioregeneration percentages could be higher than the concentration gradient-driven desorbability. This was attributed to exoenzymatic bioregeneration occurring due to the activity of extracellular enzymes secreted by microorganisms in these systems. These extracellular enzymes can diffuse into the activated carbon pores where they can react with the previously adsorbed compounds resulting in their desorption from the carbon surface and degradation. However, the effect of extracellular enzymes on bioregeneration was not conclusively proven in any of the literature studies on bioregeneration because extracellular enzymes were not directly used for the purpose of bioregeneration. In this study, enzymatic bioregeneration of activated carbon was investigated by directly using an extracellular enzyme, laccase, which is known from the literature to catalyze the oxidation reactions of phenolic substances and is commercially available in its pure form. Therefore phenol, 2-nitrophenol, and bisphenol-A were used as the target compounds. For this purpose, batch adsorption, abiotic desorption, enzymatic degradation and enzymatic bioregeneration experiments were performed using two different activated carbon types; thermally and chemically activated ones. The results showed that there was a significant difference between the total enzymatic bioregeneration efficiencies and abiotic desorption efficiencies for each phenolic compound depending on the activated carbon type. Thereby, exoenzymatic bioregeneration has been quantitatively shown for the first time in the literature.

 Activated carbon is widely used in combination with biological treatment systems for the treatment of organic compounds, which are refractory or toxic in conventional biological treatment systems. In these systems, compounds adsorbed on activated carbon may desorb within time due to a concentration gradient between adsorbent and the bulk liquid caused by the biodegradation of substrates in the liquid phase by microorganisms. The desorbed compounds are further biodegraded by microorganisms. This mechanism is called bioregeneration of activated carbon. Previous studies showed that bioregeneration percentages could be higher than the concentration gradient-driven desorbability. This was attributed to exoenzymatic bioregeneration occurring due to the activity of extracellular enzymes secreted by microorganisms in these systems. These extracellular enzymes can diffuse into the activated carbon pores where they can react with the previously adsorbed compounds resulting in their desorption from the carbon surface and degradation. However, the effect of extracellular enzymes on bioregeneration was not conclusively proven in any of the literature studies on bioregeneration because extracellular enzymes were not directly used for the purpose of bioregeneration. In this study, enzymatic bioregeneration of activated carbon was investigated by directly using an extracellular enzyme, laccase, which is known from the literature to catalyze the oxidation reactions of phenolic substances and is commercially available in its pure form. Therefore phenol, 2-nitrophenol, and bisphenol-A were used as the target compounds. For this purpose, batch adsorption, abiotic desorption, enzymatic degradation and enzymatic bioregeneration experiments were performed using two different activated carbon types; thermally and chemically activated ones. The results showed that there was a significant difference between the total enzymatic bioregeneration efficiencies and abiotic desorption efficiencies for each phenolic compound depending on the activated carbon type. Thereby, exoenzymatic bioregeneration has been quantitatively shown for the first time in the literature.

 Activated carbon is widely used in combination with biological treatment systems for the treatment of organic compounds, which are refractory or toxic in conventional biological treatment systems. In these systems, compounds adsorbed on activated carbon may desorb within time due to a concentration gradient between adsorbent and the bulk liquid caused by the biodegradation of substrates in the liquid phase by microorganisms. The desorbed compounds are further biodegraded by microorganisms. This mechanism is called bioregeneration of activated carbon. Previous studies showed that bioregeneration percentages could be higher than the concentration gradient-driven desorbability. This was attributed to exoenzymatic bioregeneration occurring due to the activity of extracellular enzymes secreted by microorganisms in these systems. These extracellular enzymes can diffuse into the activated carbon pores where they can react with the previously adsorbed compounds resulting in their desorption from the carbon surface and degradation. However, the effect of extracellular enzymes on bioregeneration was not conclusively proven in any of the literature studies on bioregeneration because extracellular enzymes were not directly used for the purpose of bioregeneration. In this study, enzymatic bioregeneration of activated carbon was investigated by directly using an extracellular enzyme, laccase, which is known from the literature to catalyze the oxidation reactions of phenolic substances and is commercially available in its pure form. Therefore phenol, 2-nitrophenol, and bisphenol-A were used as the target compounds. For this purpose, batch adsorption, abiotic desorption, enzymatic degradation and enzymatic bioregeneration experiments were performed using two different activated carbon types; thermally and chemically activated ones. The results showed that there was a significant difference between the total enzymatic bioregeneration efficiencies and abiotic desorption efficiencies for each phenolic compound depending on the activated carbon type. Thereby, exoenzymatic bioregeneration has been quantitatively shown for the first time in the literature.

 Aktif karbon, geleneksel biyolojik arıtma sistemlerinde refrakter veya toksik olan organik bileşiklerin arıtımında biyolojik arıtma sistemleriyle kombinasyon halinde yaygın olarak kullanılmaktadır. Bu sistemlerde, aktif karbon üzerinde adsorbe edilen bileşikler, mikroorganizmaların sıvı fazındaki substratları degrede etmesi neticesinde oluşan konsantrasyon gradyanı nedeniyle desorbe olabilir ve daha sonrasında biyolojik olarak parçalanabilir. Bu mekanizmaya aktif karbonun biyorejenerasyonu denir. Önceki çalışmalar, biyorejenerasyon yüzdelerinin konsantrasyon gradyanı kaynaklı desorplanabilirlikten daha yüksek olabileceğini gösterdi. Bu durum bu sistemlerde mikroorganizmalar tarafından salgılanan hücre dışı enzimlerin aktivitesiyle gerçekleşen ekzoenzimatik biyorejenerasyona atfedildi. Bu hücre dışı enzimler, aktif karbon gözeneklerine girerek, daha önce adsorbe edilen bileşiklerle reaksiyona girebilmekte ve bunların karbon yüzeyinden desorpsiyonuna ve degrede olmasına neden olabilmektedir. Ancak literatürde biyorejenerasyon üzerine yapılan çalışmaların hiçbirinde enzimlerin biyorejenerasyon üzerindeki etkisi kesin olarak kanıtlanamamıştır. Çünkü hücre dışı enzimler bu amaçla doğrudan kullanılmamıştır. Bu çalışmada, literatürde fenolik maddelerin oksidasyon reaksiyonlarını katalize ettiği bilinen hücre dışı bir enzim olan ve ticari olarak saf haliyle temin edilebilen lakkaz enzimi kullanılarak aktif karbonun enzimatik biyorejenerasyonu araştırılmıştır. Hedef bileşikler olarak fenol, 2-nitrofenol ve bisfenol-A kullanılmıştır. Bu amaçla termal ve kimyasal olarak active edilmiş iki farklı aktif karbon tipi kullanılarak kesikli adsorpsiyon, abiyotik desorpsiyon, enzimatik biyodegradasyon ve enzimatik biyorejenerasyon deneyleri yapılmıştır. Sonuçlar, aktif karbon tipine bağlı olarak her bir fenolik bileşik için toplam enzimatik biyorejenerasyon verimleri ile abiyotik desorpsiyon verimleri arasında önemli bir fark olduğunu göstermiştir. Böylece literatürde ilk kez ekzoenzimatik biyorejenerasyon niceliksel olarak da gösterilmiştir.

Makale detayları

Enzymatic Bioregeneration of Activated Carbon by Laccase

Yazarlar:

Özgür Aktaş | Zeynep Merve Tiryaki | Işık Çoban

Yayıncı:

Marmara University

Ana Başlıklar:

Çevre Yönetimi (Diğer)

Dergi:

International Journal of Advances in Engineering and Pure Sciences Vol.36 Issue 2, pp.160-172

Belge Tipi:

Makale

Yayın Tarihi:

1/2024

Belge Dili:

İngilizce

Document ID (Org No.):

2001319787

pISSN:

2636-8277

activated carbon

phenol

2-nitrophenol

bisphenol-A

bioregeneration

laccaseaktif karbon

fenol

2-nitrofenol

bisfenol-A

biorejenerasyon

lakkaz

Sayı

Makale detayları

Yazarlar: Özgür Aktaş | Zeynep Merve Tiryaki | Işık Çoban

Yayıncı: Marmara University

Ana Başlıklar: Çevre Yönetimi (Diğer)

Dergi: International Journal of Advances in Engineering and Pure Sciences Vol.36 Issue 2, pp.160-172

Belge Tipi: Makale

Yayın Tarihi: 1/2024

Belge Dili: İngilizce

Document ID (Org No.): 2001319787

pISSN: 2636-8277

Sayı

Yazarlar:

Özgür Aktaş | Zeynep Merve Tiryaki | Işık Çoban

Yayıncı:

Marmara University

Ana Başlıklar:

Çevre Yönetimi (Diğer)

Dergi:

International Journal of Advances in Engineering and Pure Sciences Vol.36 Issue 2, pp.160-172

Belge Tipi:

Makale

Yayın Tarihi:

1/2024

Belge Dili:

İngilizce

Document ID (Org No.):

2001319787

pISSN:

2636-8277