The cracking of the biggest case ever involving the production and sale of recycled edible oil from swill, points not just to health hazards from eating food cooked with such oil. It also raises the question of how such waste edible oil can be reused in a friendly manner.

What is particularly noteworthy is the involvement of a "bio-energy" firm in the case, in which 32 suspects have been detained for the production and sale of the hazardous oil in 14 provinces.

The firm based in Shandong province collected waste cooking oil under the pretense of recycling it into bio-diesel, but it actually recycled the waste oil into cooking oil and sold it to restaurants.

It is indeed laudable that the Ministry of Public Security has smashed such a large-scale illegal operation. But it won't be the last as long as there is the need for such oil and making and selling it is profitable.

There should be standards for the testing of edible oil so that the oil recycled from kitchen waste can be prevented from re-entering the market. And those who buy and use such recycled oil should also be subject to heavy fines so that people are deterred from buying and using it. If there is no market there will be no incentive to sell the recycled swill to restaurants.

Yet, waste cooking oil is a kind of resource that should be able to be recycled and put to proper use. There is a firm in east China's Fujian province, which can produce 980 kilograms of bio-diesel from 1 ton of waste cooking oil. Now the firm has three factories that have the capacity to produce 100,000 tons of bio-diesel and it will increase its production capacity by another 100,000 tons next year.

The consumption of edible oil, including animal fat, amounts to 22 million tons a year in the country and the waste cooking oil is estimated at more than 2 million tons. If they can be recycled into bio-diesel, it will not only be a boon to efforts to save energy it would also make it impossible for restaurants to use it as edible oil.

Government policy is needed to encourage more such projects and if necessary preferential policies should be introduced to make it possible for producers of such recycled bio-diesel to make profits.

There should also be regulations and their effective enforcement to regulate the collection of waste cooking oil and thus make it easy and possible for this raw material to reach the bio-diesel producers.

This would be a positive way of solving the problem of recycled hazardous cooking oil that returns to kitchens posing a threat to diners' health.