SECTION IV 

 MATERIALS AND PROCEDURES 



DESALINATION PLANT OPERATION 



The desalination plant is a 50 stage flash-evaporator type (Fig. 2). 

 Its general operation has been described by Clarke et at (19 70) and 

 Popkin (1969). The plant draws saline water from three 120 feet deep 

 wells, acidifies it with H„SO, to remove carbonates, adjusts the pH 

 with NaOH, heats and degasses the water, and passes it through a series 

 of 50 chambers with ever diminishing pressures. As the hot water enters 

 each chamber it boils violently, cools slightly, then flows to the next 

 chamber where an increase in vacuum causes it to boil again. 



The steam created by the boiling brine is condensed on cooling tubes, 

 drips onto product trays and is then pumped through a filter and into 

 the city water system. Brine flowing through the system is recycled 

 many times with only a portion drawn off each cycle as brine blowdown. 

 The blowdown and a smaller volume of cooling water (called reject water) 

 empty into an open sump and flow through a three-foot pipe into Safe 

 Harbor canal. The discharge is located on the upper portion of the canal 

 wall about three feet under the surface of the water. 



CHARACTERIZATION OF THE EFFLUENT 



The effluent was monitored in three ways; by continuous recording instru- 

 mentation, by measurements and calculations based on the operating charac- 

 teristics of the plant, and by periodic manual sampling and laboratory 

 analysis of the effluent. 



Sample water for continuous monitoring was drawn from the effluent pipe 

 by a nonmetallic pump and passed through a bubble remover reservoir to 

 continuous recording instrumentation. Temperature was recorded from a 

 thermister probe located in the effluent pipe and conductivity from a 

 probe in the bubble removing reservoir. The pH was measured in a flow- 

 through cup in a small laboratory facility adjacent to the desalination plant 



Copper was measured by a flow-through Hach Chemical Company, Inc. , Model 

 2006 copper analyzer. Temperature, conductivity, and pH data were 

 processed by a Hydrolab, Inc., battery-operated Hydrolab IV system. 



Throughout the study continuous monitoring instruments were a problem. 

 The copper analyzer suffered from clogged capillaries and electronic 



17 



