Identification of Particle Size Classes Inhibiting Protozoan Recovery from Surface Water Samples via U.S. Environmental Protection Agency Method 1623

Giardia species recovery by U.S. Environmental Protection Agency method 1623 appears significantly impacted by a wide size range (2 to 30 μm) of particles in water and organic matter. Cryptosporidium species recovery seems negatively correlated only with smaller (2 to 10 μm), presumably inorganic particles. Results suggest constituents and mechanisms interfering with method performance may differ by protozoan type

Efficacy of different antifouling treatments for seawater cooling systems

In an industrial seawater cooling system, the effects of three different antifouling treatments, viz. sodium hypochlorite (NaClO), aliphatic amines (Mexel1432) and UV radiation, on the characteristics of the fouling formed were evaluated. For this study a portable pilot plant, as a side-stream monitoring system and seawater cooling system, was employed. The pilot plant simulated a power plant steam condenser, having four titanium tubes under different treatment patterns, where fouling progression could be monitored. The nature of the fouling obtained was chiefly inorganic, showing a clear dependence on the antifouling treatment employed. After 72 days the tubes under treatment showed a reduction in the heat transfer resistance (R) of around 70% for NaClO, 48% for aliphatic amines and 55% for UV, with respect to the untreated tube. The use of a logistic model was very useful for predicting the fouling progression and the maximum asymptotic value of the increment in the heat transfer resistance (DRmax). The apparent thermal conductivity (l) of the fouling layer showed a direct relationship with the percentage of organic matter in the collected fouling. The characteristics and mode of action of the different treatments used led to fouling with diverse physicochemical properties