For the question concerning % solids of wastewater sludge generated, we generally measure the sludge according to weight and not according to the % wastewater generated. Can the unit of measure be changed to kg?

Here, we are asking about the dry weight of your sludge. Normally, with sludge, you get a mixture of water and solids, and in testing, you will derive the dry weight. The percentage is calculated as the dry weight divided by the original weight of the sludge, multiplied by 100. This means you do not need to enter kg units here and can enter the percentage.