Sentence:  Research at Fayette , Missouri on oxidation ponds has shown that the BOD in the treated effluent varied from 30 to 53 mg / <WSD>l</WSD> with loadings from 8 to 120 lb BOD / day / acre . 
Meaning of the word marked with <WSD> tags:  a metric unit of capacity, formerly defined as the volume of one kilogram of pure water under standard conditions; now equal to 1,000 cubic centimeters (or approximately 1.75 pints)