دانلود رایگان مقاله انگلیسی بازبینی جامع در مورد تصفیه فاضلاب کارخانه در مسیر پیشرفت فیزیکی و شیمیایی و بیولوژیکی - اشپرینگر 2018

Abstract

Fermentation distilleries produce a considerable volume of high-strength wastewater, known as stillage, having unconvertible organic fractions, lower pH and high percentage of dissolved organic and inorganic matters. Molasses stillage comprises higher level of chemical oxygen demand of 80–140 g/l, biochemical oxygen demand of 40–65 g/l, inorganic impurities and dark brown colour. Grain stillage contains comparatively lower chemical oxygen demand of 40–60 g/l. This stillage is acidic in nature (pH of 3.4–4.1) and exhibits considerable pollution potential upon discharge of untreated or partially treated wastewater into water body. Physical, chemical, biological and integrated processes for treatment of distillery stillage, which have been established by several researchers, are discussed in this review article. These treatment methods are discussed with focus on process details and current challenges, prospect and opportunities of future research and development. By utilizing distillery stillage as substrate in microbial fuel cell or integrated or combined fungal aerobic treatment followed by microbial fuel cell system, encouraging observations are demonstrated recently in terms of achieving the required treatment efciency to meet the discharge standards, simultaneous bioelectricity generation and value-added products recovery. Such treatment system can ofer a suitable solution for treatment of distillery wastewater in coming days.

Conclusion and outlook

MFC technology has been adopted as a single-stage treatment process with raw distillery wastewater or with anaerobically digested distillery efuent; however, the process failed to achieve more than 60% efciency of COD removal, when operated under normal conditions without posing any modifcation in operating conditions and reactor design. Multi-stage processes involving pre-treatment with selective bacterial or fungal species have been followed by further treatment of pre-treated efuent in MFC. It could achieve almost complete removal of organic matter by demonstrating up to 99% COD removal, producing efuent having COD of less than 500 mg/l, which can meet the inland disposal quality standards. However, limited studies have been performed combining aerobic/anaerobic technologies with MFC technology. The major disadvantage of this bioelectrochemical process is the need of dilution water to reduce the organic matter present in the fungal pre-treated efuent, before further treatment in MFC. This efuent dilution may possibly be eliminated by following two repeated fungal co-cultivation process followed by treatment in MFC or by recycling the treated efuent. Hence, the future research should be focussed to develop such eco-friendly and economical treatment strategies in order to achieve higher treatment efciency, efuent standards with lesser environmental footprints and reduce cost of overall treatment. Most importantly, apart from reducing suspended solids and organic matter, the possibility of recovering single cell protein, biopolymers, enzymes and many other derivatives from fermentation broth makes the fungal fermentation technology proftable for industrial implementation.