The NEFCO Launder Cover System

Algae is More Than a Nuisance

Algae growth on launder trough and weir surfaces is a continuous operations and maintenance problem in treatment plants everywhere. At its most benign level, algae is an unsightly nuisance that requires frequent cleaning by plant personnel. This is a costly, continuous process that robs valuable time of maintenance personnel. Unchecked, algae growth can have more severe and expensive consequences, disrupting weir overflow and clogging filter screens and pump mechanisms. In plants equipped with UV disinfection systems, algae in the effluent may significantly reduce the systems' effectiveness and cause serious maintenance issues.

NEFCO's patented* Launder Cover System has been designed specifically to inhibit the growth of algae on the launder trough and weir surfaces by blocking sunlight from striking those areas. Without sunlight, the algae is largely eliminated or reduced to a light film that is easily washed away with a hose. Constant cleaning by maintenance personnel is a thing of the past, as is the threat of operations or equipment problems caused by algae growth.

The Cover can also be used in odor control applications where it serves to contain odors emanating from the area of the weir and launder. It is estimated that more than 80% of the odors in the tank are produced when the effluent breaks over the weir. Properly sealed, the Cover becomes an essential element in an effective odor control system.

Finally, the Cover acts to keep ice, snow and debris from the launders, adding to the overall appearance and operation of the facility.

Once installed, and unlike "brush" or "sweep" systems, the Cover operates 24/7/365, requires virtually no maintenance and has no parts to be replaced.

Launder Cover Design

Launder Covers generally consist of a fixed Mounting Section that serves as the base for the Cover, and a hinged Cover Section that opens to provide access for inspection and maintenance. Together these two parts extend from the tank wall over the trough and weir and to a point just on the inboard side of the scum baffle.

There are two basic configurations. The first is the Tank Wall Configuration where the Mounting Section attaches to the outer tank wall and the Cover opens toward the outer wall. The second is the Weir Wall Configuration where the Mounting Section is fastened to the weir wall and the Cover opens inward toward the center of the tank.

For most plants the Tank Wall Configuration has several drawbacks:

• The operator has to reach over the cover or use a pole or other tool to engage the cover lift ring and open the cover.
• The cover opens back toward the operator and obstructs his view and access to the trough.
• There is no simple way to lock the cover closed for security purposes or to prevent wind damage.

(Click on Image for Larger View)

The Weir Wall Configuration overcomes these problems, because:

• The Cover latch/handle is located immediately in front of the operator.
• The Cover opens away from the operator, providing an unobstructed view of the launder and weir and the operator can access the trough if necessary.
• The latch/handle is a rugged, spring-loaded mechanism that locks the Cover closed but opens easily.

NEFCO offers both Cover configurations, but the Weir Wall Mounted Cover is the choice of most plant personnel. The Weir Mount section is secured over the weir wall with stainless steel brackets. The hinged Cover Section arches over the trough and rests on a cover support flange fastened to the tank wall. Alternate panel units feature a molded tab that seals the panel seams from sunlight. NEFCO has taken this design one step further and offers the Weir Wall configuration with integral scum baffle.

There is also a NEFCO Launder Cover System designed for radial troughs or situations where the trough is set away from the outer tank wall. In these cases the Cover is configured as a hinged hood supported on both sides of the launder trough.

Each Cover panel is manufactured of tough uv-protected fiberglass and specifically designed to withstand the rigors of both the application and the environment. The Cover System is custom engineered to the specific configuration and dimensions of the clarifier for optimum performance and ease of installation. There are no expensive parts to wear out and replace. Once installed, the Cover is a rugged, sturdy structure that is virtually maintenance-free.

*NEFCO has been granted four US patents for its Launder Cover System designs, including Patents 5,670,045; 5,965,023; 6,216,881 and 6,712,222.

The NEFCO Launder Cover System ... a sensible, cost-effective means of algae control.