An suggestion for the Processing of Sewage in Hong Kong

This is such a simple and stupid idea I wonder if no government already practicing it. My thought is since it take million of taxpayer’s money to process sewage from all the toilet in the cities, why can’t the Department responsible for processing of sewage SELL the processed material as organic fertilizer? Why must it waste all the money by neutralized all the germ(i.e. fertilizer and nutrients for the plants) then release it into sea? Even if the intend for the process is to minimize the organic pollution to the ocean, we nevertheless pollute the ocean, why should we think ONLY from the perspective of human being but not for plants and animals? Doesn’t we waste all the energy to neutralize all the useful material for the plants in the processing of sewage while commercial entity take energy in the making of them? It is touchy political issue to talk about Polluter’s fee, why can’t we let the polluter’s waste product to pay for its own pollution?