N in wastewater was determined with Zn-FeSO4, reduction and alkali distillation, P was measured by potassium persulfate digestion and molybdenum-blue colorimetry, and Cu, Zn, Pb by the AAS, Hg and As by the AFSTable 1 shows that N, P, and heavy metals concentration of wastewater from pig farms were all
different, and the highest concentration of heavy metals was Zn with the lowest concentration, Hg