Discharges subject to licence under section 63 entering waste water works shall be subject to such pre-treatment as required in order to:

(a) protect the health of staff working in collection systems and treatment plants;

(b) ensure that waste water works are not damaged;

(c) ensure that the operation of a waste water treatment plant and the treatment of sludge are not adversely affected;

(d) ensure that discharges from treatment plants do not adversely affect human health or the environment or prevent receiving waters from complying with any European Community Directives;

(e) ensure that sludge can be disposed of safely in an environmentally acceptable manner.