COOLING PONDS POSSIBLE AMELIORATIONS

Introduction

For many industries such as cement plants, power plants, natural gas generating stations, pulp and wood processing facilities and refineries as a continual source of cool water, cooling ponds constitute an important part of the water treatment process. Altough the primary heat transfer mechanism in a cooling pond is evaporation, the abscence of vertical mixing in the pond generates layers of warm and cold water form (thermoclines) which result in horizontal laminar layered flow, restricting the movement of warmer water to the surface for evaporation and cooling (short-circuiting). Thus, the pond's cooling capacity is not utilized at 100%.

Industrial cooling ponds are generally used as surge ponds, runoff ponds and make-up water ponds. When these ponds become stagnant, it often promotes algae growth and odors, reducing their efficiency.

Solution

By homogenizing the total volume of water retained by exposing warm water to the cooler atmosphere, we greatly increase evaporation. Ambient temperatures higher than water temperatures generally characterized warm weather. The soil surrounding the pond will be used as a cooling source if it works properly. Water must be circulated past the pond bottom in order for this to occur. A reduction of the overall pond water temperature is obtained by mixing the cooler "bottom" water throughout the water column. The expansion of air bubbles as they move from an area of high pressure at the bottom of the pond to lower pressure at the top and ultimately atmospheric pressure above the water generate heat transfer.

For a PNW lagoon, the air is introduced through ADS fine bubble diffusers at the bottom of the cooling pond, facilitating grid coverage aeration, which is critical for uniform mixing and the prevention of short-circuiting especially in large or irregular shaped cooling ponds.

The sustain of beneficial communities of natural soil and water bacteria in clear water provided by Bacta-Pur® bioaugmentation limit algae growth and reduce solid accumulation and plant growth in water bodies.

AquaMats® biofiltration curtains provide massive surface area for high concentrations of beneficial bacteria that further stress and reduce algae and plant growth and create in-water barriers to reduce short-circuitin.

Result

With a PNW optimized cooling pond, it is possible to achieve water temperatures at or near the wet bulb ambient temperature during the peak temperature month.

Vertical mixing (destratification) and improvement of both make-up and cooling water quality directly influences production rates by optimizing the efficiency of cooling ponds.