Comma seperated data in Dropdownlist

var list = objZoneDAO.GetAllZonesByYardID(Convert.ToInt32(rddlYard.SelectedValue)).Where(Z => Z.ZoneType == Convert.ToInt32(Enums.ZoneType.Mustering_Zone) && Z.ZoneStatus == Convert.ToInt32(Enums.ZoneStatus.Active)).ToList();

DataTable dt = new DataTable();

DataRow dr = dt.NewRow();

dr[0] = dt.Columns.Add("ZoneName", typeof(string));

dr[1] = dt.Columns.Add("ZoneId", typeof(string));

string s = string.Empty;

string zid = string.Empty;

foreach (var item in list)

{

s += item.ZoneName + ",";

zid += item.ZoneID + ",";

}

s = s.Remove(s.LastIndexOf(','));

zid = zid.Remove(zid.LastIndexOf(','));

dr[0] = s;

dr[1] = zid;

dt.Rows.Add(dr);

rddlMuster.DataTextField = "ZoneName";

rddlMuster.DataValueField = "ZoneId";

rddlMuster.DataSource = dt;

rddlMuster.DataBind();

rddlMuster.DataTextField = "ZoneName";

rddlMuster.DataValueField = "ZoneID";

rddlMuster.DataSource = objUtilsDAO.GetZonesByYardID(lstYards.FirstOrDefault().YardID).Where(zm => zm.IsCS == false && zm.ZoneType == (int)Enums.ZoneType.Mustering_Zone).OrderBy(zm => zm.ZoneName);

rddlMuster.DataBind();