Q.how can I save my anthurium?
I purchased an Anthurium last fall, which was doing fine til recently. . . noticed the leaves had brown through them and today several are shriveled and drying. The plant came already growing on a piece of lava, so I put it on a bed of decorative pebbles which sat in a bowl of water. The roots seemed to grow down into the water which I kept filled so it wouldn’t dry out.

Certified GKH Gardening Expert
Have you fertilized it at all. They need only a very light fertilizer high in phosphorous, but if you have not given any fertilizer, it may need a little to help it.
It sounds like you are growing it in an almost water based medium, so try giving it just a little fertilizer once every other month so it can get the nutrients it would normally get from soil.