Pilot cooling water studies conducted at a Southern California landfill/cogeneration station demonstrated a successful chemical treatment program for recirculating cooling water that used unnitrified, reclaimed, Title 22 water as the primary makeup water source. The constituents in the reclaimed water are supplied by variety of residential and waste water sources resulting in a water quality that may vary to a greater degree than domestic water supplies. This water contains high concentrations of orthophosphate, ammonia, chlorides and suspended solids. The impact of which, under cycled conditions is calcium orthophosphate scaling, high corrosion of yellow metal and mild steel, stress cracking of copper alloys and stainless steel and rapidly growing biological activity.
A mobile cooling water testing laboratory with two pilot recirculating water systems modeled the cogeneration station?s cooling tower operating conditions and parameters. The tube and shell, tube side cooling heat exchangers were fitted with 443 admiralty, 90/10 copper nickel, 316 stainless steel and 1202 mild steel heat exchanger tubes. Coupons and Corrater? electrodes were also installed. A chemical treatment program consisting of 60/40 AA/AMPS copolymer for scale, deposits and dispersion, sodium tolyltriazole for yellow metal corrosion, and a bromination program to control the biological activity was utilized in the pilot systems. Recirculating water orthophosphate concentrations reached levels of 70 mg/L as PO,, and ammonia concentrations reached levels of 35 mgL, as total NH3. The study successfully demonstrated a chemical treatment program to control scale and deposition, minimize admiralty, 90/10 copper nickel and carbon steel corrosion rates, prevent non-heat transfer yellow metal and stainless steel stress cracking, and control the biological activity in this high nutrient water.
Water shortages in Southern California have led to an increased use of reclaimed water, commonly referred to as Title 22 water. This tertiary effluent derives its name from California?s Administrative Code Title 22 which strictly regulates the treatment, process, and the use of this water as defined by the code. Currently, the major consumption of reclaimed water is for agriculture, irrigation of golf courses, parks, and nurseries, and the recharge of ground water. The nitrogen and phosphorous present in this water make it ideal for agricultural and landscape purposes.
The industrial community is one of the largest consumers of fresh water. However, only a very small percentage of reclaimed water is used for industrial purposes. Government regulations to conserve fresh water supplies are putting pressures on industrial users to accept more reclaimed water for process applications. A large percentage of industrial water usage is for cooling water applications. Replacing this fresh water consumption by industrial cooling water systems using reclaimed water would have a positive impact in conserving fresh water supplies.
Currently, the majority of cooling water systems now on reclaimed water are in the utility power industry.? Power utility operations are more acceptable for waters of somewhat lesser quality due to their operational parameters and conditions. They are generally more uniform than conditions found in refineries or chemical manufacturing plants In contrast, refinery and chemical plants cooling water systems operate under more. extreme, and erratic
