Evaluation of six aerator modules built on venturi air injectors using clean water test.

Six aerator modules constructed using venturi air injectors connected in either series or parallel were evaluated and compared for their oxygen transfer coefficients (OTC), standard oxygen transfer rate (SOTR), and standard oxygenation efficiency (SOE) determined by clean water tests. Modules in series (module a, b, c) included one, two, and three venturi injectors, respectively. The aerator module with two (module d) and three (module e, f) venturi injectors in parallel were used, while module f had less friction and more even flow rate in each line compared with module e. The results showed that the OTC, SOTR, and SOE for the six different module configurations (module a, b, c, d, e, f) were 4.54, 3.79, 3.58, 8.37, 5.93 and 11.87 h(-1); 0.10, 0.09, 0.09, 0.18, 0.15, and 0.31 kgO(2)/h; and 0.07, 0.06, 0.06, 0.12, 0.10, and 0.21 kgO(2)/kWh, respectively. The observations indicate that a 3-fold increase in SOTR and 3.5-fold increase in SOE can be obtained by simply changing the way that venturi air injectors are connected, which suggests that it is possible to improve the aeration efficiency of a venturi type aeration system by innovative aerator module designs. In view of the situation that the venturi aeration systems currently used for swine manure lagoons need significant improvement in their performance in order to match the cost-effective requirement, more research in aerator module development is needed so that effective control of odor from liquid swine manure lagoons can be achieved at an affordable cost. The technology such developed can also be applied to other livestock species.