Division EMISSION LEVELS ASSOCIATED WITH BAT (BAT-AELs) FOR EMISSIONS TO WATER

United Kingdom

The BAT-AELs for emissions to water given in these BAT conclusions refer to values of concentrations (mass of emitted substances per volume of water), expressed in the unit mg/l.

These BAT-AELs refer to the average of samples obtained during one year, meaning the flow-weighted average of all 24-hour flow-proportional composite samples, taken in one year with the minimum frequency set for the relevant parameter and under normal operating conditions.

The formula for calculating the flow-weighted average of all 24-hour flow-proportional composite samples is:

c_{w} = \sum_{i = 1}^{n} c_{i} q_{i} ∕ \sum_{i = 1}^{n} q_{i}

where:

c_w

flow-weighted average concentration of the parameter;

number of measurements;

c_i

average concentration of the parameter during ith time period;

q_i

average flow rate during ith time period.

Time-proportional sampling can be used provided that sufficient flow stability can be demonstrated.

All BAT-AELs for emissions to water apply at the point where the emission leaves the installation.