8. What is the key difference between primary and secondary sewage treatment?
|
Primary sewage treatment Secondary sewage treatment |
||||
|
1 |
lt is a mechanical process involving the removal of coarse solid materials. |
1 |
lt is a biological prcess involving the action of microbes. |
|
|
2 |
lt is inexpensive and relatively less complicated. |
2 |
lt is a very expensive and complicated process. |
|
