Anaerobic treatment of high-strength cheese-whey wastewaters in laboratory and pilot UASB-reactors

Start-up of the laboratory (3 l) UASB-reactor treating raw high-strength (up to 77 g COD/l) cheese-whey wastewaters as well as the treatment efficiencies (TE) and the maximal admissible organic loading rates (OLR) have been investigated under mesophilic (35°C) and submesophilic (20–30°C) conditions. A stable operation of the reactor with the TE higher than 90% on the total COD has been demonstrated up to the OLR of 28.5 and 9.5 g COD/l•day for mesophilic and submesophilic regimes, respectively. A successful start-up of the pilot (10.74 m3) non-thermostated UASB-reactor treating raw cheese-whey wastewaters at ambient temperatures (ca. 24°C) has been completed in 3 months. Further exploitation of the reactor at the design OLR of 6.5 g COD/l•day showed its good operational stability with the TE close to 95% on the basis of total COD. After a proper start-up, the UASB-reactors can cope with preacidificated cheese-whey wastewaters (pH of about 4) even at elevated OLR that eliminates the necessity of alkalinity supplementation.