Sludge Disposal: More Than Resourcing

In order to solve the problem of sludge disposal, China put forward the slogan of four principles (reduction, stabilization, harmlessness and resourcing) many years ago.

l Reduction: The sludge has a high water content. The newly collected sludge is liquid and will become solid only after dehydration and drying. It is not only smaller in volume, but also easy to stack, transport and consume.

l Stabilization: Due to the high content of organic matter in the sludge, it will be corrupted. After dehydration, fermentation and digestion, macromolecular organic matter will be decomposed into stable small molecule organic matter, which is convenient for transportation and disposal.

l Harmlessness: The sludge contains a large number of pathogenic bacteria, parasite eggs and viruses, which can be dehydrated, digested and dried to kill most of the eggs, pathogenic bacteria and viruses of the parasites and improve the health indicators.

l Resourcing: The content of organic matter and nitrogen, phosphorus and potassium in the sludge is high, which can be used as fuel or organic fertilizer after the above treatment.

This year, we have come to the step of "comprehensive implementation" and put forward the Implementation Plan for Harmless Treatment and Resource Utilization of Sludge. The goal is to achieve a harmless disposal rate of more than 90% of urban sludge by 2025. At the beginning, the four principles were put together, which shows that four principles are equally important, but now resourcing is more concerned than other three principles. Why?

1.        The four principles are in different levels technically.

2.        Highlighting resourcing makes it easier for owners to pay.

3.        Resourcing is more favored by investors.

The core of the four principles of sludge is to solve the pollution problem. Of course, the reuse of some resources is icing on the cake, and sludge is unlikely to become a new energy source. The process of four principles requires a large amount of capital, which cannot be separated from the market. It is easier to open the market door by emphasizing resourcing. The four principles are a long-term process. You can't deny your outstanding performance in the other three principles just because you haven't reached the resourcing level. A new technology is a good way as long as it can improve the status quo.