The Treatment Method of Preserves Wastewater
Preserves is a kind of licorice cold product with various fresh fruit (green) as the main raw material, which is a kind of food deeply loved by people.
The waste water, juice and sugar liquid produced in the process of preserves are often poured out as waste water. The waste water is directly discharged into the river, which makes the river water have a serious sour smell. A large number of waste water infiltrates into the farmland, which will make the farmland salinized and alkalized year by year and reduce the grain production.
Preserves wastewater is a kind of strongly acidic wastewater with high concentration of organic pollutants. Using coagulation to pretreat wastewater can reduce the concentration of suspended solids and organic pollutants, and reduce the harm of wastewater to the environment.
In addition, the high valence cations in PAC can reduce the surface charge energy, the electrostatic repulsion, the agglomeration of organic particles, the increase of settling opportunity, and the decrease of organic content in the preserves wastewater.
The content of floating matter in water is one of the indexes to measure the degree of water pollution. After coagulation, sedimentation and filtration, natural water becomes clear.
The amount of coagulant is directly related to the treatment effect of wastewater, too much or too little will affect the treatment effect. There is an optimal value of reagent dosage, and the COD removal rate corresponding to this value is the highest.
When the dosage is lower than this value, COD removal rate increases with the increase of coagulant dosage; when the dosage is higher than the optimal value, COD removal rate decreases with the increase of dosage.
When the amount of coagulant is close to the best value, the surface charge energy of insoluble organic matter is the smallest, agglomeration and sedimentation are the most significant, and COD removal rate is the highest.
After that, the charge energy increases with the increase of the dosage, the electrostatic repulsion force between the particles increases, the agglomeration and sedimentation effect worsens, and the COD removal rate decreases.
Common processing methods
For example, the traditional activated sludge process, biological contact process, SBR process, oxidation ditch process, etc. have lower unit basic investment cost and higher removal effect.
But it also has its shortcomings, such as sensitive to load impact, poor operation stability, poor integrity rate of long-term continuous operation of mechanical equipment, relatively large floor area and so on.
Activated sludge process
Activated sludge process is a widely used biological treatment process at home and abroad. It has the advantages of high treatment capacity and good effluent quality, but it has the disadvantages of low load, high construction and operation costs, and complex management.
One is the combined process of composite mode (referred to as composite process), the other is the combined process of series mode (referred to as series process). The typical way of the composite process is to add suspended packing to the activated sludge aeration tank as the carrier of microbial attachment growth, so that the suspended activated sludge in the reactor and the attached biofilm work together to remove the organic pollutants in the wastewater, so the process composition model is single.
The series process is to combine the biofilm process and the activated sludge process in series according to the characteristics of wastewater quality and the requirements of treatment depth. The combination mode of series process is flexible: the series can be two-stage or multi-stage; the series sequence can be the material membrane method.
Biological contact oxidation
The biofilm packing is installed in the aeration tank. The microorganism adheres to the surface of the packing to form the biofilm. The aerated wastewater flows through the packing layer and contacts with the biofilm. Under the action of the biofilm, the wastewater is purified.
Generally, jet aeration technology can be used. The equipment structure is simple and durable, with less investment, less maintenance and high oxygen utilization rate. The main equipment is water pump and jet air extractor.
Biological contact oxidation process is a kind of facultative activated sludge process and biofilm process, so it has two advantages.