Development of A Cascade Aeratror for Small and Medium Fish Farmers in Nigeria

Aeration devices are designed to create a greater amount of contact between air and water to enhance the transfer of gases and increase oxidation. A cascade aerator is one of gravity aerators and classified as water-into-air aerators and one of the oldest and most common aerators. It consists of a series of steps that the water flows over (similar to a flowing stream). The main features of the cascade aerator were electric motor pump used as prime mover which was of half horse power capacity, and cascade geometry (300 x 100 x 50mm), with eight steps of 1200 mm total lengths made of stainless material and mounted on collector basin made of mild steel and all were supported by angle iron made of galvanized material. Water samples were collected and chemical property (dissolved oxygen) was determined in accordance with American Public Health Association (APHA, 2005). Data were analyzed using descriptive statistics. The result indicated that overall oxygen transfer coefficient, cascade aerator standard aeration efficiency, standard oxygen transfer rate were ranged from 5.15 – 8.21hr-1, 0.11 – 0.21KgO2kW-1hr-1 and 0.04 – 0.08KgO2hr-1 respectively. The cascade aerator improved the water quality by addition of oxygen leading to appreciable increase in the fish stock density which has been a major setback of low-income fish farmer in Nigeria. Keywords: oxygen dissolved, overall oxygen transfer coefficient, cascade aerator standard aeration efficiency, standard oxygen transfer rate,