In municipal sludge treatment, the selection of dewatering agents is mainly reflected in the following aspects:
Complexity of sludge properties
Diverse ingredients:
Municipal sludge composition is complex, including organic matter, inorganic matter, microorganisms, heavy metals and other substances.
The moisture content, viscosity, particle size and other physical properties of the sludge are also different, which will affect the selection of dehydration agents.
Variable nature:
The properties of sludge vary with the season, treatment process, sewage source and other factors.
For example, sludge moisture content may increase during the rainy season, and more efficient dewatering agents need to be selected.
Two. Diversity of drug types and difficulty in selection
Inorganic and organic chemicals:
Inorganic agents (such as polyaluminum chloride, ferrous sulfate, etc.) and organic agents (such as polyacrylamide, etc.) have advantages and disadvantages.
Inorganic agents usually have a lower cost, but may have some impact on the environment; Organic chemical dehydrating effect is good, but the cost is higher.
Influence of drug parameters:
For organic agents, such as polyacrylamide, its molecular weight, ionic degree, charge density and other parameters will affect the dehydration effect.
The selection of appropriate chemical parameters requires comprehensive consideration of sludge properties, treatment technology, equipment conditions and other factors.
Three. Equipment compatibility and process requirements
Compatibility of dewatering equipment:
Different sludge dewatering equipment (such as belt filter press, plate and frame filter press, centrifuge, etc.) have different requirements for chemicals.
For example, some devices may be better suited to use a particular type of agent or parameter.
Processing requirements:
Municipal sludge treatment processes are diverse, including gravity concentration, air flotation concentration, centrifugal concentration and other pretreatment processes, as well as pressure filtration, centrifugal and other dehydration processes.
Different treatment processes have different requirements for the selection of pharmaceutical agents.
Consideration of environmental and safety factors
Environmental requirements:
The selection of agents needs to comply with environmental regulations to avoid secondary pollution to the environment.
Security:
The safety of the drug is also an important factor to consider when selecting.
It is necessary to choose an agent that is harmless to the human body and easy to store and transport.
V. Balance between economy and cost-benefit
Pharmaceutical cost:
The cost difference of different agents is large, it is necessary to choose a lower cost agent under the premise of ensuring the dehydration effect.
Long run cost:
In addition to the cost of the drug itself, it is also necessary to consider the cost of equipment maintenance and energy consumption during long-term operation.
Choosing an agent that is easy to operate and low in maintenance can reduce long-term operating costs.