Chemical wastewater makes many chemical companies "scratch their heads", its treatment difficulty is not a joke, even your own production supervisor does not know the composition of wastewater, can not use appropriate wastewater treatment methods to solve.Chemical wastewater is the wastewater generated in the chemical production process, and we discharge it up to the standard through a complete wastewater treatment system - consisting of three parts: pretreatment unit, biochemical treatment unit and advanced treatment unit. Below we share two cases of chemical wastewater treatment for your reference, how chemical wastewater is treated.
In a case of chemical wastewater treatment, the COD concentration reaches 8000mg L and the total nitrogen reaches 1000mg L, which is a "double high" industrial wastewater, and we need to stably meet the discharge standards for both pollutants.
Our project mainly uses biochemical treatment technology, that is, through a combination of anaerobic biological treatment and aerobic biological treatment to remove most of the organic matter and ammonia nitrogen pollutants in chemical wastewater. Other physical and chemical methods are used to help stabilize the biochemical treatment and undertake advanced treatment to ensure that the water quality of the wastewater is within our control.
The UASB reactor is used for anaerobic biological treatment, and it is widely used in all high-efficiency anaerobic reactors, including food wastewater and high-concentration chemical wastewater.
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When the UASB reactor is working, the wastewater enters the bottom of the reactor through uniform water distribution, and the granular sludge (sludge floc) is in a suspended state under the action of rising water flow and bubbles. The lower part of the reactor is a sludge bed with a higher concentration, and the upper part is a suspended sludge layer with a lower concentration, where organic matter is converted into methane and carbon dioxide gas.
In order to better treat ammonia nitrogen pollutants and reduce the cost of wastewater treatment, anaerobic ammonia oxidation technology is adopted, which is a new type of biological treatment technology. Anaerobic ammonia oxidation (Anammox) refers to the biological denitrification process in which anaerobic ammonia bacteria oxidize ammonia nitrogen with NO2- as the electron acceptor and convert NH4+ and NO2- into N2 and a small amount of NO3- under anaerobic conditions.
Since bicarbonate and carbon dioxide are consumed in the process, there is no need for additional carbon sources, which not only reduces operating costs, but also prevents secondary pollution.
Subsequently, the subsequent problems of pollutants such as ammonia nitrogen and organic matter are solved through multiple contact oxidation ponds, and the effluent can meet the discharge standard.
In the pretreatment unit, we have set up air flotation, Fenton and other devices to ensure that the influent COD, suspended solids, etc. can be within the range we need, which are emergency facilities and are generally not activated.
In a chemical wastewater treatment case, "high concentration of refractory organic wastewater" was discharged, not only the COD concentration reached 30,000mg L, but also the B C value was less than 03. It is difficult to be degraded by microorganisms.
As a result, we have more pretreatment and biochemical treatment methods in this project than in the previous case – to enhance the wastewater treatment capacity and improve the stability of the sewage station.
Among them, the pretreatment adopts the "iron-carbon micro-electrolysis technology", which is a common technology currently used in high-concentration refractory organic wastewater, through which we can degrade organic matter, greatly improve the biodegradability, and use the effluent for subsequent biochemical treatment.
It is the use of the iron and carbon materials in the solution of the point is very poor, the metal iron through corrosion and constitute countless microgalvanes, these microgalvanic cells produce a large number of electrons and active reducing substances, can reduce the inorganic pollutants and organic pollutants in the wastewater, form colloidal particles, and further purify through adsorption, flocculation, precipitation and other actions, and separate the pollutants in the water body, so as to achieve the purpose of removing pollutants.
In the anaerobic biological treatment, the "UASB reactor" was also used, and due to the high COD concentration in the influent water, we established the "hydrolysis acidification technology" in the front.
Hydrolysis acidification technology has the characteristics of low operating cost, improved biodegradability, increased acidification, and reduced toxicity, although the COD removal rate is not high, but we can reduce the impact of wastewater on the subsequent UASB reactor and improve the biodegradability of wastewater.
From the two cases, we can know that chemical wastewater also needs to design a suitable wastewater treatment system according to water quality and other conditions, so that it is easier to achieve standard discharge and reduce wastewater treatment costs.