P

Complete wastewater treatment units manufactured for small communities

and installations not served by municipal systems. These units, which do

not require continuous operational supervision, supply primary or some

biological treatment. see Primary treatment. see Secondary treatment

Solid particles placed in a column in either orderly or random fashion

to give a large surface area for mass transfer. See Fluidized bed. see

Particulate scrubber

see Packed bed

see Polynuclear aromatic hydrocarbons

see Peroxyacetyl nitrate

see Normal distribution

Maximum permitted concentrations, usually in micrograms per cubic

meter, for chemicals that are toxic or carcinogenic.