Environment expert says wastewater increases yield, but poses risk to citizens
WASA official says city produces wastewater at a rate of 400 mgd
By Abdul MananLAHORE: Crop yield increases when irrigated with wastewater, but such crops transmit enteric (waterborne and food borne) and alternaria diseases in human beings, Daily Times learnt.
Because of rapid urbanisation, the reuse of wastewater has become an attractive option for irrigating crops. A Water and Sanitation Agency official said, “Lahore, with more than an eight million population, produces wastewater at a rate of 400 million gallons per day (MGD).”
Sources said that after collection the wastewater was sent to six pump stations located along the bank of River Ravi. The wastewater was pumped into sullage carriers, which drains the water to the river. The land along the sullage carriers was extensively used for growing seasonal crops, they said.
According to an estimate 67 percent of the wastewater reaches the river whereas the rest is utilised to irrigate crops. Farmers pump the wastewater from these sullage carriers into their fields. Lahore’s more than 400 MGD wastewater cultivates an area of about 1,500 hectares – crops being cultivated are seasonal vegetables, fodder, cereals, sugarcane and citrus.
National College of Business Administration and Economics Environmental Sciences Director Dr Muhammad Khursheed said, “Reuse of wastewater has two main reasons – low cost method and reuse of nutrients. He said that in the past three decades the use of wastewater for crop irrigation has been increased.”
He said the growth of crops with wastewater was as good as that with plain water and fertilizers, but the crop yield decreased with an increase in the proportion of diluted water. He said he had studied crops, which were irrigated with Shadbagh Pump Station’s wastewater. He said, “Untreated wastewater at this pump station consists of 80 percent domestic sewage, 5 percent sullage and 15 percent wastewater from industries in Misri Shah and Shadbagh.”
He said he had found that the wastewater was rich in organic matters. However, he said, a large number of toxic metals had also been traced.
He said he had studied tomatoes, cabbage, radish, onions, potatoes, cucumbers, sugarcane and fodder. He said, “These crops can transmit enteric diseases. During the study, a mild attack of alternaria was observed on radish and cauliflower. I collected 320 samples of vegetables irrigated by wastewater and found that they contained micro organisms.”
He said, “Crops should not be irrigated with wastewater. We need to make laws in order to stop farmers from irrigating their crops with wastewater.”
Environmental Protection Agency’s (EPA) Environment Impact Assessment Department Deputy Director Naseemur Rehman said the EPA had ordered agencies concerned to treat wastewater before sending it to the sullage carriers. He said, “Lahoris consume poisonous vegetables which are irrigated with wastewater.
Source: Daily Times, 24/5/2008