Deicing agents for removal of ice and snow from highways and streets are essential to wintertime road maintenance in most areas of the U.S. Due to the ever-increasing use of highway deicing materials, there has been growing concern as to environmental effects resulting from these practices. The state-of-the-art report critically reviews the available information on methods, equipment and materials used for snow and ice removal; chlorides found in rainfall and municipal sewage during the winter; salt runoff from streets and highways; deicing compounds found in surface streams, public water supplies, groundwater, farm ponds and lakes; special additives incorporated into deicing agents; vehicular corrosion and deterioration of highway structures and pavements; and effects on roadside soils, vegetation and trees. Highway deicing can cause injury and damage across a wide environmental spectrum. Recommendations describe future research, development and demonstration efforts necessary to assess and reduce the adverse impact of highway deicing.

Suitable for university undergraduate courses but also serves as a useful reference book for graduate students and practicing engineers.

Flushing of a lake means reducing the pollution by clean inflow with an equivalent outflow of polluted water, a process by which clean water both displaces and mixes with the polluted water. Parameters influencing the effectiveness of the cleansing stream, most important and manageable under laboratory conditions, were investigated. Parameters studied were: inlet velocity, inlet width, depth, and basin shape. Testing was conducted on two depths, two inlet widths, three inlet velocities, and four elliptical basins. Primary purpose of the project was to evaluate the various parameters to determine their influences on flushing efficiency, and develop prediction equations based on geometric and flow characteristics of the systems tested. Analysis were completed to develop a test program, analyze the system for comparison with experimental results, and develop prediction equations which incorporate analytical and experimental results of the study.

To determine the feasibility of eutrophication control by controlling carbon, three major areas were studied: the steady state, in which the growth rates of algae at various constant, maintained dissolved carbon dioxide concentrations were determined; the non-equilibrium, where natural atmospheric replenishment was the sole carbon source; and algal growth with inorganic bicarbonate as the sole carbon source. In studying growth rates of Chlorella, Microcystis, and Anabaena with respect to carbon availability, it was found that algae can utilize dissolved concentrations of carbon dioxide much lower than those from atmospheric equilibria.

Of a number of methods available for phosphate removal from waste water, chemical precipitation (often called coagulation) using aluminum, ferric iron, ferrous iron and lime is considered to be the most economical. The objective of the present study has been two-fold: To evaluate the effects of pH and reactant concentration on the rate and efficiency of phosphate removal from synthetic and secondary effluent wastewaters and on the nature of the precipitates formed; and to compare the data on the Fe(II)-phosphate precipitation system with the available data for Fe(III)- and Al(III)-phosphate systems. Most of the experiments in the study were conducted on pure orthophosphate solutions and in the absence of dissolved oxygen. Only a limited number of tests were made of the use of ferrous iron for orthophosphate removal from wastewaters containing dissolved oxygen.

The operation of three storm standby tanks contiguous to an intercepting sewer which serves both combined sewers and sanitary sewers was investigated to determine the effectiveness of the tanks in improving the quality of the waste water prior to its discharge into the river. Based on influent and effluent sampling data collected during the study period, storm standby tank facilities reduce significantly concentration of the solids and B.O.D. in the waste water in storm runoff periods. The extent of reduction is dependent to a major degree on the detention time of flow passing through the tanks. Improvement of dissolved oxygen resulting from passage of waste water through the tanks is very substantial, especially during periods when the dissolved oxygen content of the influent is low.