Removal of the organic content from a bleached kraft pulp mill effluent by a treatment with silica-alginate-fungi biocomposites

Abstract

This study attempts a treatment strategy of a bleached kraft pulp mill effluent with Rhizopus oryzae or Pleurotus sajor caju encapsulated on silica-alginate (biocomposite of silica-alginate-fungi, with the purpose of reducing its potential impact in the environment. Active (alive) or inactive (death by sterilization) Rhizopus oryzae or Pleurotus sajor caju was encapsulated in alginate beads. Five beads containing active and inactive fungus were placed in a mold and filled with silica hydrogel (biocomposites). The biocomposites were added to batch reactors containing the bleached kraft pulp mill effluent. The treatment of bleached kraft pulp mill effluent by active and inactive biocomposites was performed throughout 29 days at 28°C. The efficiency of treatment was evaluated by measuring the removal of organic compounds, chemical oxygen demand and the relative absorbance ratio over time. Both fungi species showed potential for removal of organic compounds, colour and chemical oxygen demand. Maximum values of reduction in terms of colour (56%), chemical oxygen demand (65%) and organic compounds (72-79%) were attained after 29 days of treatment of bleached kraft pulp mill effluent by active Rhizopus oryzae biocomposites. The immobilization of fungi, the need for low fungal biomass, and the possibility of reutlization of the biocomposites clearly demonstrate the industrial and environmental interest in bleached kraft pulp mill effluent treatment by silica-alginate-fungi biocomposites.

Diverse Metabolic Capacities of Fungi for Bioremediation

“…Members of the basidiomycota, such as T. versicolor and white-rot fungi Pleurotus ostreatus have been reported to degrade model PAHs in solid-state fermentation (SSF) during growth on agroindustrial wastes, such as orange peels [29]. Bioremediation/decolourization of coloured effluents from sugar industry, textile dye, bleached kraft pulp mill, leather tanning effluents has been reported in case of fungi belonging to various groups including Aspergillus, Penicillium and alkalophilic white-rot fungi indicating diverse substrate preference of these fungi [14,[60][61][62][63][64]. Coffee pulp could be decaffeinated in presence of fungi under controlled conditions with extra nutrients for applications in animal feed preparation or for bioethanol production as was studied in case of fungi such as Aspergillus restrictus, Chrysosporium keratinophilum, Fusarium solani, Gliocladium roseum, Penicillium and Stemphylium [65].…”

Strategies based on silica monoliths for removing pollutants from wastewater effluents: A review

“…The immobilization of living organisms such as bacteria or fungi avoids their potential release into the environment and the unpredictable organisms-environment interactions, a further positive aspect of the biocomposites in comparison to traditional biological processes such as biological secondary treatment using aerobic or anaerobic reactors (Duarte et al, 2013;Meunier et al, 2010;Kato et al, 2005). The presence of foreign organisms in the environment can cause growth imbalance especially if they are more resilient than the autochthonous species (Perullini et al, 2010).…”

“…In Table 2 are displayed the studies published between 2007 and 2012 involving the use of biocomposites based on silica monoliths with immobilized living organisms/cells or enzymes to remove pollutants from wastewater effluents or to degrade specific chemical compounds such as phenols, dyes and estrogens in laboratory prepared solutions. Duarte et al (2013Duarte et al ( , 2012 proceeded with a two-step encapsulation of Pleurotus sajor caju, Trametes versicolor and Rhizopus oryzae in alginate beads, which in turn were surrounded by a bulk silica monolith gel; this was the basis of a strategy to treat BKPME and OMW. The immobilization of fungi, the need for low fungal biomass, their performance in terms of color (>56% reduction) and organic compounds removal (>70%), as well as the possibility of reutilization (1% COD loss efficiency after a second cycle) of the biocomposites clearly demonstrate the industrial and environmental interest in BKPME and OMW treatment by silica-alginate-fungi biocomposites.…”

“…More recently strategies that use silica monoliths have been employed for the removal of chemical compounds such as phenols, fatty acids, sterols among others from wastewater effluents or prepared solutions which have been performed in laboratory environment only. These strategies involve monoliths either as composites (El-Safty et al, 2011a) or biocomposites when they include immobilized living organisms/cells or biomolecules (enzymes) (Duarte et al, 2013;Perullini et al, 2010). Adsorption is one of the most attractive and efficient methods for purification and separation of trace organic contaminants in wastewaters and therefore several composites based on silica monoliths have been developed for such purpose.…”

“…Monolithic materials have been rapidly developed during the last years and are becoming an important tool in separation science and in other areas of chemistry (Buchmeiser, 2007). Since the 1970s silica monolithic materials have been used in a wide array of applications, such as in coatings either for solid-phase microextraction fibers or for monolithic columns in chromatography, for encapsulation of biomolecules in affinity chromatography, as well as for encapsulation of biomolecules in microfluidic and microarray chips (Buchmeiser, 2007;Kato et al, 2005;Ghanem and Ikegami, 2011), and more recently assayed for pollutants removal in wastewater effluents (Duarte et al, 2012(Duarte et al, , 2013.…”