The front-page story May 23 about the Maryland hog farm by Fern Shen brought to mind a process said to have been developed in India, which could help these problems.

I remember reading of an animal waste-treatment program that produced enough methane gas from the droppings of a single cow to furnish heat and light for a family. The remaining solids were basically odor free and provided better fertilization than raw waste.

What was involved was a concrete tank with a dome-shaped lid. At the top of the dome was a valve and pipe. At the side was a chute into which the cow droppings were loaded. Another hatch at a higher level provided access to solid waste that floated on the surface of the water that the tank contained.

The account said the manure was scooped into the tank where it sank and decomposed into methane and solids. The methane bubbled to the top of the tank and collected in the dome; then it was piped out to the farmhouse and burned for heat and light. In three days the solid material floated to the top. There it was skimmed off, allowed to dry, then spread on the farmer's fields.

The problem in India was that the cost of constructing the pit was beyond the means of most farmers. Here the cost problem would be greatly alleviated by the scale of the hog farm operations. As I understand The Post's story, the farms already have holding tanks for waste. Thus all that might be needed would be some retrofitting and piping of existing tanks and possibly some new ones.

Odor control both from the fresh waste and the fertilizer would solve environmentalists' and neighbors' concerns, while energy needs of the farms could be met. Any excess gas might be compressed and sold.

It seems something like this should be considered in the search for a solution to the conflict in producing cheap pork and maintaining a healthy environment.

JULIUS W. WALKER JR.

Washington