Extracted text: Which of the following is/are correct about BOD in municipal sewage? 1. It must be removed because it is always pathogenic and thus poses a risk to public health 2. It is utilized by the microorganisms which thus reduces adverse environmental effects It is typically wholly particulate and can be removed by settling 3. It is partly solid and can only be partially removed by settling 4. 5. It is a carbon and energy source for microorganisms in the sludge O 3,4 and 5 O 1,2 and 3 O 1,3 and 5 O 2, 4 and 5
Extracted text: The preliminary stage in a wastewater treatment plant 1. Removes only large items that cannot be taken up in the biological process 2. Removes the large items to protect the plant equipment Includes flow measurement devices to help in the control and operation of the biological stage 3. 4. Normally produces significant BOD removal that aids in meeting regulatory restrictions 2 and 3 O 1 1, 2, 3 4