Document Type: Original Research Paper
University of Warmia and Mazury, Poland
Water and Sewerage Corporation in Ostroda, Poland
In the present study, the increase of organic loading rate (OLR) influences the biomethanisation of sewage sludge. The research was conducted at technical scale in wastewater treatment plant in Tyrowo (near Ostróda, Poland). It has been shown that the increase of OLR, by adding co-substrates, cause the increase of biogas production but not biogas yield coefficient. The substrates used for anaerobic digestion were primary sludge and excess sludge. As co-substrates there were fats, thin stillage and whey. The highest total biogas production of 115977 m3/month and electricity production of 231.3 MWh were obtained for the highest OLR of 1.88 kg VS/m3.d. Anaerobic co-digestion of primary and excess sewage sludge with co-substrates at the highest OLR caused an increase of pH to 7.7 and volatile fatty acid concentration to 616 mg/dm3, but there was no loss to the stability of the process. Regardless of organic loading rate, the concentration of ammonium nitrogen was within the optimal range.