kilogram per day

The kilogram per day is the ordering unit of process chemistry. Chlorine and alum consumption at a water plant, polymer feed to a sludge press and antiscalant to a cooling tower are all budgeted, ordered and logged in kilograms per day, because the daily total is what appears on the invoice even when the pump meters it out in millilitres per minute.

The unit's quiet superpower is that the metric dosing formula has no constant in it at all. A milligram per litre is a gram per cubic metre, and a megalitre is a thousand cubic metres, so dose times flow gives feed directly: mg/L times ML/d equals kg/d, exactly. A 2 mg/L chlorine dose on a 10 ML/d plant is 20 kg/d, done in your head, and a standard 68 kg chlorine cylinder lasts about three and a half days at that rate. The customary-unit world needs the famous 8.34 factor for the identical computation, as the pound-per-day entry explains, and the site's chemical feed solvers carry both versions of the arithmetic.

The same daily basis serves the other direction, for what a process produces rather than consumes: sludge yields, emissions loadings and recovery rates are reported in kg/d for the same invoice-and-logbook reasons.