Design, Construction, and Performance Evaluation of an Ozonation Pilot Plant

The treatment of water and wastewater may involve numerous chemical and physical unit processes. Each unit process is selected on the basis of its ability to accomplish specified treatment objectives. Ozone treatment is one such chemical unit process alternative. Ozonation is commonly practices abroad. Presently, nearly one thousand water treatment facilities in Western Europe use ozone for various applications. Ozone treatment of water is not common in the United States with just five installations as 1979. However, rising costs of chemicals, recent advances in ozone technology, and new treatment regulations and discharge requirements have enhanced the use of ozone as a water and wastewater treatment alternative. The theory of the reactions of ozone for treatment of water and wastewater is well recorded. However, due to the site-specific nature of the ozonation process, it is difficult to predict he practical or economic feasibility of ozone treatment without supporting data. These data may be best obtained by conducting ozonation experiments at the prospective site on a pilot-plant scale. The objectives of this research were: (1) To design, specify, and direct the construction of a portable ozonation pilot plant suitable for water and wastewater treat feasibility studies. (2) To evaluate the performance of the ozonation pilot plant under field conditions. The contents of this paper include a review of the factors related to the design and construction of a pilot plant ozonation system. The components of the pilot plant are also described. Finally, the results of a performance evaluation of the pilot plant are discussed

The role of suspension characteristics in continuous gravity thickening

Sludges resulting from water and wastewater treatment processes consist of agglomerated individual particles producing aggregates of various sizes and densities. Particle size, particle density, aggregate size and aggregate density are characteristics which determine the amenability of a suspension to continuous gravity thickening. To investigate the effects of these suspension characteristics on compression zone behavior, precipitation softening water treatment sludges and diatomaceous earth suspensions were gravity thickened in a pilot-scale continuous thickener. The effects of raking on thickening performance in the compression zone and the effects of suspension characteristics on channeling were also investigated;The behavior of the sludges in the compression zone of the continuous thickener was characterized using sludge concentration profiles and permeability and compressibility relationships. Suspension aggregate size and density were evaluated using a velocity-voidage correlation for hindered settling of the suspensions;When judged on the basis of the sludge concentration profiles and resulting underflow concentrations from the continuous thickener, the thickening performance of the sludges examined in this investigation was significantly affected by the sludge aggregate characteristics. Correlations between aggregate characteristics and permeability and compressibility explained the differences in thickening behavior;The occurrence of channeling in the compression zone was a function of aggregate characteristics for the diatomaceous earth suspensions, whereas compression zone channeling occurred for all softening sludges examined in this investigation, regardless of aggregate properties;Raking the compression zone obliterated channeling, causing poorer thickening performance of those suspensions which channeled in the compression zone