UCLA

Synthetic dyes are used in the production of many consumer goods globally. Consequently, they are commonly released into local environments from industrial processes and mismanagement of dye wastewater. Dyes have hazardous impacts on both environment and public health owing to their chemical toxicity and pigment release into aquatic ecosystems. Historically, chemical and physical methods have been most commonly used for the treatment of dye wastewater. However, these approaches may face limitations in certain circumstances since they can be expensive, energy intensive, and not environmentally friendly. Biological treatments may provide a useful alternative or augmentation to situations when conventional methods are insufficient.In this study, immobilized fungi were proposed as effective and sustainable agents for dye removal. To achieve this, Pleurotus ostreatus (P. ostreatus) was inoculated onto solid substrates, including sorghum, bran, husk, and their various combinations. P. ostreatus immobilized on sorghum (PO-SORG) produced the highest enzyme activity, and was further tested for its ability to degrade specific dye compounds. Laccase was the major enzyme produced by PO-SORG and played a central role in dye decolorization. In batch reactors, Reactive Blue 19 (RB-19), Indigo Carmine, Acid Orange 7 (AO-7), and Acid Red 1 (AR-1) were degraded by PO-SORG by 82%, 91%, 91%, and 61%, respectively. In more environmentally relevant conditions, PO-SORG decolorized RB-19 or AR-1 in a synthetic textile wastewater (STWW) by 73% and 15%, respectively. PO-SORG was also used to treat a sample of real textile wastewater (RTWW) from a Los Angeles factory and decolorized it by 60%. In extreme conditions, PO-SORG resisted high temperatures and pHs to achieve substantial dye degradation. Furthermore, PO-SORG was successfully reused up to three consecutive batch cycles and removed 72% of RB-19 in the third round. Collectively, these results demonstrate that PO-SORG is a promising strategy for the treatment of dye wastewater under relevant industrial and environmental conditions.