How to choose sludge treatment and disposal technology

Solution:

1. Sludge thickening.

Concentration is a commonly used method of solid-liquid separation and can be accomplished in two ways: the solids float to the top of the mixture, or settle to the bottom of the mixture. The former is generally referred to as air flotation, while the latter is called gravity concentration.

The purpose of sludge thickening is mainly to separate excess water from the sludge as much as possible before sludge digestion or dewatering.

Generally speaking, sludge thickening can effectively reduce the treatment capacity required for sludge treatment follow-up units such as digestion and dewatering, and the cost savings of subsequent units due to volume reduction are much higher than the setting and operation costs of sludge thickening units, so setting up sludge thickening units can help reduce the total cost of sludge treatment process.

2. Sludge conditioning.

Chemical conditioning. The main purpose of sludge conditioning is to promote the solid-liquid separation of sludge. Among the currently available technologies, the most common method is to add coagulants such as ferric chloride, lime or organic polymer flocculants to the sludge, and sludge incineration ash can also be used as a sludge conditioner. The addition of coagulants to turbid liquids such as sludge promotes the agglomeration of solids, making them easier to separate from water.

In recent years, the application of organic polymer flocculant in sludge conditioning has become more and more extensive, and the organic polymer flocculant is easy to handle, occupies a small volume, is simple to use, and is very effective. The flocculant is generally injected into the sludge before dewatering and mixed well with the sludge.

3. Heat treatment.

Another sludge conditioning method is to heat the sludge at high temperature (175 230 ) and high pressure (1000 2000 kpa) to release the bound water in the sludge solids, thus improving the dewatering characteristics of the sludge. The advantage of heat treatment is that the dewatering of sludge after conditioning is better than the use of chemical conditioners; The disadvantage is that the operation and maintenance of the system is more complicated, and the sludge heat treatment will also produce a high concentration of cooking liquid, which will significantly increase the load on the treatment unit when it is returned to the sewage treatment plant.

Sludge treatment methods have the following points:

1) Establish a multi-microbial strain system: change the traditional process, the bacterial phase structure based on aerobic microorganisms, and a variety of microorganisms, the activated sludge concentration in the reactor is large, the pollutant removal efficiency is high, and the effluent quality is stable.

2) Near-zero discharge of organic sludge: The sludge reduction system is mainly based on the complementary cooperation of a variety of microorganisms, and the macromolecular organic pollutants are gradually degraded into small molecule organic matter, and the final oxidation and decomposition into carbon dioxide and water.

3) Sewage gasification phosphorus removal: The sludge reduction system is used to strengthen biological nitrogen and phosphorus removal, and the gasification phosphorus removal process under the action of multi-strain microorganisms is proposed, developed and applied, which is completely different from the traditional biological phosphorus removal process and is a new high-efficiency and low-consumption biological phosphorus removal process.

4) Synchronous denitrification: Under certain conditions, nitrification will produce a large amount of NO2- accumulation. In order to shorten nitrification, the oxygen supply is greatly reduced by the use of anaerobic ammonia oxidation, which greatly reduces the energy consumption of aeration and the carbon source required for denitrification, so as to achieve the purpose of efficient denitrification.

1. Reduction: Due to the high water content, large volume and fluidity of sludge, after reduction, the volume of sludge can be reduced to one-tenth of the original, and it is transformed from liquid to solid, which is convenient for transportation and consumption.

2. Stabilization: The content of organic pollutants in the sludge is high, and it is easy to decay and produce foul odor, after stable digestion, some organic pollutants that are easy to decay are decomposed and transformed, and the odor of the part that is not easy to decay is also greatly reduced, which is convenient for follow-up treatment and disposal.

3. Harmless: In the sludge, especially the initial sludge contains a large number of pathogenic bacteria, parasite eggs and viruses, which is easy to cause the spread of infectious diseases. After harmless treatment, if this chain is carefully processed after digestion, it can kill most of the roundworm eggs, pathogenic bacteria and viruses in the sludge, and greatly improve the hygiene index of the sludge.

4. Recycling: sludge contains a large amount of organic matter, and its calorific value is between 10000 and 15000kj kg (dry sludge), which is equivalent to coal and coke, and can obtain heat in incineration for production, and because sludge is rich in nitrogen, phosphorus, potassium and organic matter, it is an organic fertilizer with high fertilizer efficiency. It is also because the sludge converts organic matter into biogas in anaerobic digestion, which is used as fuel for biogas boilers and biogas engines, saving operating costs.