<p-table #tt class="table"[value]="myList">
     ....
     <tr>
       <th>
        <p-dropdown appendTo="body" *ngSwitchCase="'state'" [options]="states"
        (onChange)="tt.filter($event.value, 'state', 'equals')"></p-dropdown>
       </th>
     </tr>
     ....
</p-table>

export class Component implements {
    @ViewChild('tt') tt: DataTable;
    myList: any;

    getList(){
    Promise.resolve(...)
        .then(res => {
                this.myList = res;
                this.tt.filter('created', 'state', 'equals');
              });
            }
     }