There could be three scenarios here.

• Scenario 1: “direct discharge” if the third-party facility only treats the wastewater of this particular factory without mixing it with any others and the final discharge of effluent is to a receiving body. Maybe due to the lack of space to build an ETP, the factory may have it externally. All MRSL parameters, conventional parameters and anions, and heavy metals, and of course, sludge parameters should be tested based on the major sludge disposal pathway.

• Scenario 2:” Indirect discharge without pretreatment”. If the facility stores the effluent and then sends it to an external treatment plant i.e. CETP. The sampling point should be from the container and the parameters applicable to indirect discharge without pretreatment (i.e. the MRSL and 5 metals) should be checked. 
• Scenario 3:If any pretreatment to the effluent is carried out before storing it in a tank and sending it to the external treatment agency i.e. CETP, then the effluent sample, taken before this pretreatment process, should be sampled to test ZDHC MRSL and 5 metal parameters. Any sludge that is generated due to this pretreatment process (such as flocculation) should be collected and tested according to the major sludge disposal pathway.
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