Characteristics　of　organic　matter　may　affect　the　residual　aluminum　after　the　coagulation　process.　This　study　reported　the　results　of　a　survey　for　one　drinking　water　treatment　plant　and　measured　the　concentration　of　residual　aluminum　species　with　different　molecular　weights.　Survey　results　indicated　that　humic　acid　or　organicmatter　whosemolecular　weight　was　smaller　than　1500　Da　had　significant　effects　on　residual　aluminum.　All　the　treatment　processes　were　ineffective　in　removing　dissolved　organic　matter　whose　molecular　weight　was　smaller　than　1500　Da.　These　results　also　indicated　that　the　addition　of　sand　or　polyacrylamide　in　the　coagulation　process　could　greatly　decrease　the　concentration　of　humic　acid,　and　the　concentration　of　residual　aluminum　also　decreased.　These　results　revealed　that　for　all　water　samples　after　filtration,　the　majority　of　total　residual　aluminum　existed　in　the　form　of　total　dissolved　aluminum,　accounting　for　70%-90%.　The　concentration　of　residual　aluminum　produced　in　bovine　serum　albumin　solutions　indicated　that　when　the　DOC　was　larger　than　4.0　mg/L,　therewere　still　significant　differenceswhen　the　solution　pHvalue　varied　from4.0　to　9.0.　(C)　2017　The　Research　Center　for　Eco-Environmental　Sciences,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.