Fig. 6. X-ray diffraction (XRD) patterns of the alum-stabilized and untreated (the lowest Al to P molar ratio) sludge. Mineral symbols are as follows: BR, brushite; G, gypsum; VA, variscite; AL, alunogen; ST, aluminaum strengite; CR, cristabalite; Q, quartz; C, calcite; V, vaterite; and DO, dolomite.