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Industrial wastewater
Industrial wastewater treatment
Rainwater and meltwater from urbanized areas significantly affect the deterioration of water quality in water bodies. The degree of pollution of this category of waters depends on a number of factors: geographical location, climatic conditions, intensity and duration of precipitation, air pollution, sanitary condition of the catchment area, type of surface coverings of the territories; the presence of nearby industrial zones, highways and the volume of transport loads.
Main pollutants of rainwater and meltwater
The main ingredients that pollute rainwater and meltwater are suspended solids, petroleum products, synthetic surfactants (SPS), nitrogen compounds, and heavy metal salts.
Oil and oil products entering water bodies create various forms of pollution: an oil film floating on the water, oil products dissolved or emulsified in water, heavy fractions deposited on the bottom, etc. This changes the smell, taste, color, surface tension, and density of water, reduces the amount of oxygen dissolved in it, harmful organic substances appear, and the water acquires toxic properties and poses a threat not only to aquatic organisms, but also to humans.
Detergents (washing detergents) contribute a significant share to water pollution. They include surfactants as an active base and various additives: alkaline and neutral electrolytes, peroxide compounds, substances that prevent the resorption of pollutants. Detergents, getting into water bodies, cause foaming, worsen the organoleptic properties of water, disrupt the processes of oxygen exchange, have a toxic effect on fauna, complicate the processes of biological oxidation of organic substances, and interfere with the biological treatment of wastewater.
To prevent the negative impact of polluted rainwater on the environment, it is necessary to use local treatment facilities.
The composition of polluted rainwater and meltwater (using the example of the developed Potential-4 treatment facilities in Kyiv) and water purified using Potential-4 technologies is given in Table 1.
Table 1.
Potential-4 has developed technologies for purifying this category of water for facilities of various capacities. Figure 1 shows a basic technological scheme for purifying rainwater and meltwater for facilities of large capacity.
Fig. 1. Schematic technological scheme for the purification of rainwater and meltwater
1 – polluted rainwater storage tank,
1.1, 1.2. – Faggiolati pumps with cutting impeller,
2 – hydrocyclone,
3 – Flokfil flotation device, 3.1. – disc aerator,
4 – Flokfil sedimentation tank,
5 – Flocfil filter,
6 – Flocfil stabilizer, 6.1, 6.2. – Faggiolati pumps,
7 – Bargam polymer station,
8 – Etatron dosing pump,
9 – Becker blower,
10 – Bargam decanter,
11.1 – distribution well of the bioplateau, 11.2 – hydroponic type bioplateau, 11.3 – collection (control) well.
Working principle
Rainwater and meltwater from the catchment area are collected through rain collectors through the rain sewer system into a distribution well, from which polluted rainwater (all small, medium and polluted portions of storm rain) is supplied to local treatment facilities, represented by a receiving chamber-accumulator with submerged pumps, a hydrocyclone and Flokfil installations with a bioplateau. Conditionally clean water is supplied to the reservoir.
As can be seen from the data in Table 1, for polluted rainwater runoff, the determining factors for the choice of cleaning agents are suspended solids, the concentration of which significantly exceeds the MPC. These contaminants can be classified as group I dispersion, which are most efficiently removed by mechanical cleaning (using a hydrocyclone). At the same time, impurities of group II and III dispersion, which are controlled by BOD5 and HSC, are removed by 15-25%.
To remove impurities of group II, it is advisable to use a flocculant in the flotation unit of the Flokfil installation, where the redox potential (Eh) is also adjusted when water is saturated with oxygen. During the flocculation process, the aggregate state of the contaminants changes, a phase separation process occurs with their removal into sludge and sediment. Floating substances are removed through the overflow pipeline, and suspended substances from the settling part are removed into the sediment stabilizer using air lifts.
In the sedimentation tank of the Flokfil installation, finely dispersed suspended solids of group III are removed, which also enter the stabilizer.
The clarified return water is fed to the secondary purification filters of the Flokfil unit with a modified loading to remove residual concentrations of suspended solids and oil products.
After mechanical and physico-chemical treatment, the return water flows by gravity to the hydroponic type bioplateau secondary treatment facilities with higher aquatic plants (reed, cattail). The bioplateau loading (washed crushed stone) is filled with the destructors “Econadin” and “Trofoil” to intensify the process of biodestruction of organic pollutants and dissolved petroleum products.
The quality of the treated return water meets the requirements for discharge into water bodies for domestic purposes. Treated return water can be used for irrigation of the territory and green spaces.
Figures 2, 3 and 4 present technological schemes for the purification of this category of waters for small-capacity facilities. Figure 2 shows treatment facilities made in reinforced concrete wells. Figures 3 and 4 show facilities for gas stations and other similar facilities, the runoff from which is characterized by a high content of petroleum products.
Cleaning steps
As can be seen from the data in Table 1, for polluted rainwater runoff, the determining factors for the choice of cleaning agents are suspended solids, the concentration of which significantly exceeds the MPC. These contaminants can be classified as group I dispersion, which are most efficiently removed by mechanical cleaning (using a hydrocyclone). At the same time, impurities of group II and III dispersion, which are controlled by BOD5 and HSC, are removed by 15-25%.
To remove impurities of group II, it is advisable to use a flocculant in the flotation unit of the Flokfil installation, where the redox potential (Eh) is also adjusted when water is saturated with oxygen. During the flocculation process, the aggregate state of the contaminants changes, a phase separation process occurs with their removal into sludge and sediment. Floating substances are removed through the overflow pipeline, and suspended substances from the settling part are removed into the sediment stabilizer using air lifts.
In the sedimentation tank of the Flokfil installation, finely dispersed suspended solids of group III are removed, which also enter the stabilizer.
The clarified return water is fed to the secondary purification filters of the Flokfil unit with a modified loading to remove residual concentrations of suspended solids and oil products.
After mechanical and physico-chemical treatment, the return water flows by gravity to the hydroponic type bioplateau secondary treatment facilities with higher aquatic plants (reed, cattail). The bioplateau loading (washed crushed stone) is filled with the destructors “Econadin” and “Trofoil” to intensify the process of biodestruction of organic pollutants and dissolved petroleum products.
The quality of the treated return water meets the requirements for discharge into water bodies for domestic purposes. Treated return water can be used for irrigation of the territory and green spaces.
Schemes for low-power facilities
Figures 2, 3 and 4 present technological schemes for the purification of this category of waters for small-capacity facilities. Figure 2 shows treatment facilities made in reinforced concrete wells. Figures 3 and 4 show facilities for gas stations and other similar facilities, the runoff from which is characterized by a high content of petroleum products.
Fig. 2. Technological scheme for the purification of polluted rainwater and meltwater
1 – distribution well, 2 – sand trap with oil sorption boom, 3 – settling tank with coalescent insert, 4 – sorption filter, 5 – collection well, 6 – closed hydroponic bioplateau with biopreparation-destructor of oil products, 7 – filtering type bioplateau
Fig. 3. Technological scheme for cleaning contaminated rainwater and meltwater to standards for discharge into the sewer
Fig. 4. Technological scheme for the purification of contaminated rainwater and meltwater to standards for discharge into a water body (or groundwater flow)
To develop a commercial offer, the following initial data is required: Questionnaire (rainwater)
Rainwater treatment plants with a capacity of 72 m3/day, Kyiv
Rainwater treatment plants with a capacity of 81 m3/day, Kyiv
