Effect of dairy and meat wastewater irrigation on seedling growth

Abstract

Milk and meat processing industries release large quantities of nutrientrich wastewater with organic compounds (proteins, fats, carbohydrates) in high concentrations. Reusing and recycling this biodegradable wastewater for crop irrigation could be a sustainable solution once the phytotoxic effects of wastewater on crops have been investigated. Therefore, the aim of this study was to evaluate the effects of milk and meat processing wastewaters on germination percentage, seed vigour indices, the seedling tolerance index and the phytotoxicity index of pea (Pisum sativum L.), sugar maize (Zea mays saccharata), purslane (Portulaca oleracea), wheat (Triticum aestivum) and red spinach (Amaranthus dubius). The two wastewater types were collected at the inlet of the city’s sewage system and analysed to determine their physicochemical and microbiological characteristics. The seeds of all five plant species were irrigated with untreated wastewater effluents. The highest - germination percentages were obtained for wheat (92%) and the lowest for red spinach (2.5%). Wheat, purslane, pea and red spinach samples irrigated with meat processing wastewater had higher germination percentages than samples irrigated with dairy wastewater. A higher phytotoxicity was observed for sugar maize, followed by red spinach irrigated with both types of wastewater. Future investigation into the effects of effluent dilution on these types of plants is recommended.