html
<th mat-header-cell *matHeaderCellDef> M </th>
<td mat-cell *matCellDef="let element">
<mat-select [(ngModel)]="element.Monday">
<mat-option [value]="active.ID" *ngFor="let active of activeList">
{{ active.Value }}
</mat-option>
</mat-select>
</td>
</ng-container>
ts file
activeList = [
{"ID":"1","Value":"`✔`"},
{"ID":"0","Value":"X"},
{"ID":"L","Value":"L"},
{"ID":"UL","Value":"UL"},
{"ID":"PL","Value":"PL"},
{"ID":"BT","Value":"BT"},
{"ID":"H","Value":"H"}
];