Pengembangan Metode DGT Diffusive Gradient in Thin Film) dengan Binding Agent CaO/Biochar dari Cangkang Telur dan Jerami untuk Penyerapan Fosfat di Lingkungan = Development of the Diffusive Gradient in Thin Film (DGT) Method with Binding Agent CaO/Biochar from Eggshells and Rice Straw for Phosphate Absorption in the Environment.