The invention discloses a
phosphorus-free composite scale and
corrosion inhibitor and application thereof as well as a circulating
water treatment method. The
phosphorus-free composite scale and
corrosion inhibitor comprises a scale inhibitor, a dispersing agent, an
organic phosphorus-free
corrosion inhibitor and a
manganese salt, wherein the scale inhibitor consists of
polyaspartic acid and / or polyepoxysuccinic acid; the weight ratio of the scale inhibitor to the dispersing agent to the
organic phosphorus-free
corrosion inhibitor to the
manganese salt is 1:(0.2-10):(0.5-100):(0.025-1); the weight of the
manganese salt is calculated according to manganese ions. The
phosphorus-free composite scale and
corrosion inhibitor and a non-oxidizing bactericide, particularly
isothiazolinone, have a good synergistic effect, a sterilizing effect of the non-oxidizing bactericide can be obviously improved, and the fast sterilization and long
drug effect time are reflected. In addition, the phosphorus-free composite scale and
corrosion inhibitor is environment-friendly, has phosphorus-free and
nitrogen-free characteristics and meets the green and environment-friendly requirements, and the environmental burden is lightened. Moreover, the phosphorus-free composite scale and corrosion inhibitor is wide in
water quality application range and is easy to popularize and apply.