Explanation:

By constructing wetlands with plant species such as Cann indica, lemon grass (Cymbopogon), napier (Pennisetum perpureum X Pennisetum americarnum), para grass (Urochloa mutica), typha (Typha latifolia), water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes) and a weed species Agaratum Conyzoides the chemical oxygen demand in wastewaters have been reduced by 30-92%.
Moreover, yield evaluations have shown increased crop yields (14 to 40%) of crops like okra, brinjal and chilly irrigated with treated wastewater as compared to fresh water.