For the purpose of Regulation, a sewage treatment plant should satisfy the following effluent standards when ,tested for, its certificate of type test by the administration -

1. Faecal Coliform
The geometric mean of the facial coliform count of the sample of the effluent taken during the test period should not exceed 250 faecal coliform / 100 ml MPN (Most Probable Number) as determined by the multiple tube fermentation analysis or an equivalent analytical procedure.

2. Suspended Solids Standard
(a) Where the equipment. is tested on shore the geometric mean of the total suspended solid content of the samples of the effluent taken during the test period shall not exceed 50 mg/l.

(b) Where the equipment is tested aboard ship, the geometric mean of the total suspended solid content of the samples of effluent taken during the test period shall not be more than 100 mg/ above the suspended solid content of ambient water used for flushing purposes Analysis for suspended solids should be conducted in accordance with gravimetric methods approved by the Administration.

In addition to the above conditions, the plant shall be so designed that the geometric mean of 5 day Biological Oxygen Demand (BOD5) of the samples of effluent taken during the test period shall not exceed 50mg/l. Administrations should satisfy themselves that the plant is designed to reduce both soluble and insoluble organic substance to meet this requirement.