2.4.1. Determination of sCOD, sBOD5, and Biodegradability Index

The concentration of soluble COD (sCOD) was spectrophotometrically measured (at 600 nm) by dichromate method according to Standard Methods [29], using a DR2500 spectrophotometer (Hach Company). Soluble biochemical oxygen demand (sBOD5) was determined using a manometric respirometry measurement system (Lovibond Water Testing BD 600) and biodegradability index (BI) was calculated as the ratio of sBOD5 over sCOD.
