With the continuous development of industrial production, the amount of industrial sludge generated is also increasing. Industrial sludge is a solid waste with high water content and containing various harmful substances produced in the process of industrial production. If left untreated, industrial sludge can cause great pollution and impact on the environment.
Treatment methods
Treatment of sewage sludge can include a combination of thickening, digestion and dewatering processes.
Thickening
Thickening is usually the first step in sludge treatment, as it is impractical to treat thin sludge (a solid slurry suspended in water). Thickening is usually done in a storage tank called a gravity thickener. The thickener reduces the total volume of the sludge to less than half of its original volume. An alternative to gravity thickening is dissolved air flotation. In this method, air bubbles carry the solids to the surface where a thickened layer of sludge is formed.
Related products: High-efficiency sludge dehydrating agent
High-efficiency sludge dehydrating agent is an innovative, high-performance polymer with specific chemical properties that make it highly electrically neutralized for sludge dewatering and coagulation treatment.
Digestion
Sludge digestion is a biological process that breaks down organic solids into stable material. Digestion reduces the total mass of solids, destroys pathogens, and makes sludge easier to dewater or dry.
Dewatering
There are various methods of industrial sludge dewatering treatment, among which the common methods are press filtration and centrifugal dewatering.
Press filtration involves placing the sludge on a filter cloth and applying high pressure to squeeze the water out of the sludge, eventually bringing the sludge to a lower moisture content.
Centrifugal dewatering, on the other hand, uses the centrifugal force of a centrifuge to quickly separate the water from the sludge to achieve a dewatering effect.
In addition, there is a new type of industrial sludge dewatering treatment method - ultrasonic dewatering. Ultrasonic dewatering refers to placing the sludge in an ultrasonic field and using the vibration force of ultrasonic waves to separate the water in the sludge to achieve dewatering. This method has the advantages of low energy consumption and high dewatering efficiency, and is gradually being paid attention to and applied in industry.
In the industrial sludge dewatering treatment, there are also some issues that need to be noted. Firstly, appropriate dewatering treatment equipment and process should be selected to achieve better dewatering effect. Secondly, the dewatered sludge should be properly disposed of to prevent secondary pollution to the environment.
Disposal
The final destination of treated sewage sludge is usually land. The dewatered sludge can be buried underground in a sanitary landfill. It can also be distributed on agricultural land to take advantage of its value as a soil conditioner and fertilizer. Because the sludge may contain toxic industrial chemicals, it will not be distributed on land where crops for human consumption are grown.
In the absence of suitable land disposal sites, such as in urban areas, sludge can be incinerated. Incineration causes complete evaporation of water and converts organic solids into inert ash. The ash must be disposed of, but the reduction in volume makes disposal more economical. Air pollution control is a very important consideration when incinerating sludge. Proper air cleaning equipment such as scrubbers and filters must be used.
Dumping sludge in the ocean, once an economic disposal method for many coastal communities, is no longer considered a viable option. It is now banned in many other coastal countries.