Thermophilic Aerobic Treatment of Mycelia Sludge and Antibiotic Wastewater

Abstract

A major waste stream from antibiotic production is mycelia sludge. This paper explores the use of an aerobic thermophilic bioreactor with solids separation and chemical treatment (acid hydrolysis and oxidation) of excess sludge to treat this waste. This system was evaluated for reduction of total chemical oxygen demand (TCOD) and volatile suspended solids (VSS). The investigation was split into three phases. Phase 1 was the treatment of 5% [weight/volume (w/v)] mycelia waste (with an average TCOD of 92,400 mg/L and VSS of 46,000 mg/L). Phase 2 was the treatment of 1% (w/v) mycelia waste in combination with effluent from the antibiotic recovery plant (average TCOD of 36,000 mg/L and VSS of 8,900 mg/L), and Phase 3 was as for Phase 2 with chemical treatment. The system was run for 92 days without accumulation of organic or inorganic solids, even though no sludge was wasted from the reactor. The mycelia sludge proved to be readily biodegradable in Phase 1 (average TCOD destruction was 82% and average VSS destruction was 89%). An acclimatization period of 37 days was required when the mixed antibiotic wastewater was introduced in Phase 2. After this period, the average TCOD destruction was 83%. Chemical treatment in Phase 3 improved and stabilized VSS destruction (from 76% in Phase 2 to 87% in Phase 3). This study demonstrates that this system can be used to effectively treat mycelia sludge, both alone and combined with a mixed antibiotic wastewater, with minimal excess sludge formation.