Microbial Biotreatment of Actual Textile Wastewater in a Continuous Sequential Rice Husk Biofilter and the Microbial Community Involved

Abstract

Textile dying processes often pollute wastewater with recalcitrant azo and anthraquinone dyes. Yet, there is little development of effective and affordable degradation systems for textile wastewater applicable in countries where water technologies remain poor. We determined biodegradation of actual textile wastewater in biofilters containing rice husks by spectrophotometry and liquid chromatography mass spectrometry. The indigenous microflora from the rice husks consistently performed >90% decolorization at a hydraulic retention time of 67 h. Analysis of microbial community composition of bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) gene fragments in the biofilters revealed a bacterial consortium known to carry azoreductase genes, such as Dysgonomonas, and Pseudomonas and the presence of fungal phylotypes such as Gibberella and Fusarium. Our findings emphasize that rice husk biofilters support a microbial community of both bacteria and fungi with key features for biodegradation of actual textile wastewater. These results suggest that microbial processes can substantially contribute to efficient and reliable degradation of actual textile wastewater. Thus, development of biodegradation systems holds promise for application of affordable wastewater treatment in polluted environments.

Bacterial degradation of anthraquinone dyes

“…(Wang et al, 2009), Pseudomonas sp. (Forss et al, 2017), Shewanella sp. (Wang et al, 2015), Aeromonas sp.…”

Evaluation of two different carriers in the biodegradation process of an azo dye

“…Although the present study has evaluated the degradation process of one dye considering different carriers, previous studies of Forss et al [14] have shown that actual textile wastewater can affect degradation differently. Moreover, an actual wastewater stream might change content depending on different process flows.…”

“…It has been applied to remove organic compounds and the colour of textile effluents, due to their low cost, simple operation and maintenance [2,3,9]. Bacteria are performing most of the degradation in the treatment; however, fungi are also found associated in the consortia [10][11][12][13][14].…”

“…For instance, rice husks are agricultural waste available in excess which have been used as an adsorbent of dyes [26][27][28][29]. Moreover, Forss et al [14], Forss et al [30] and Türgay et al [31] have shown that rice husks can provide and sustain suitable microorganism communities for the degradation of dyes and actual textile wastewater.…”

Molecular identification of dye degrading bacterial isolates and FT-IR analysis of degraded products

“…Bioremediation is the microbial clean up approach, microbes can acclimatize themselves to toxic wastes and new resistant strains develop naturally, which can transform various toxic chemicals to less harmful forms [11]. Microbial processes can substantially contribute to efficient and reliable degradation of actual textile waste water [12]. Use of microorganisms for remediation purpose is thus a possible solution for environmental pollution since it includes sustainable remediation technologies.…”