With increasingly stringent standards for pharmaceutical wastewater discharge, many pharmaceutical companies are faced with the challenge of substandard wastewater treatment facilities. This article aims to help enterprises achieve compliant wastewater discharge through a series of technological innovations and process improvements.
Expansion and upgrading of wastewater treatment facilities
Faced with more wastewater than the design load, companies need to expand their wastewater treatment capacity and upgrade existing processes to meet the growing demand for wastewater treatment.
Due to the complex composition of wastewater, it is necessary to separate and collect wastewater according to different stages of the production process. For this purpose, separate collection tanks and their own pre-treatment facilities should be set up, equipped with automated control systems to optimize the distribution of wastewater.
For wastewater with different characteristics, targeted pretreatment measures are required:
1. High concentration of organic wastewater: This type of wastewater contains a large amount of organic matter that is difficult to degrade, and a pretreatment method that can improve its biodegradability is required. Through the combined process of microelectrolysis and Fenton oxidation, the structure of refractory substances can be effectively destroyed, thereby reducing the toxicity of wastewater and improving its biodegradability. It is estimated that the chemical oxygen demand (COD) of wastewater can be reduced to 14000~16500mg/L after this process.
2. High ammonia nitrogen wastewater: Ammonia nitrogen content is usually reduced by ammonia nitrogen blowing method. First, by adjusting the pH value to the appropriate range, and then using a blowing system to separate the ammonia gas from the wastewater, the ammonia nitrogen concentration is expected to be reduced to about 200 mg/L.
3. High-salt wastewater: For wastewater with high salt content, the method of evaporation concentration can be adopted, especially the MVR method, to realize the concentration and separation of salt in wastewater through mechanical recompression steam.
Biochemical treatment is an important part of the removal of soluble organic matter. The combination of anaerobic and aerobic processes, as well as the combination of anoxic and aerobic, allows for the effective removal of ammonia nitrogen and organics:
Conditioning tank: where the wastewater is mixed and prepared for further treatment.
UASB anaerobic tank: At this stage, most of the organic matter is removed by the action of anaerobic microorganisms.
A/O process: Removal of ammonia nitrogen from wastewater through alternating anoxic and aerobic environments.
Two-stage contact oxidation tank: further degradation of organic matter and ammonia nitrogen in wastewater.
Sedimentation tank: slurry water separation to ensure that the COD concentration of effluent is controlled at about 300mg/L.
UASB process principle
Anaerobic degradation: Under anaerobic conditions, organic matter is converted into simpler compounds such as methane (CH4) and carbon dioxide (CO2) through the metabolic activity of microorganisms, a process known as anaerobic digestion.
Sludge bed: At the heart of the UASB is the sludge bed, which contains a large number of anaerobic microorganisms. These microorganisms grow and multiply in an oxygen-free environment, forming a dense structure similar to a blanket covering the bottom of a reactor.
Upflow: Wastewater enters from the bottom of the reactor and flows upwards through the sludge bed. The upstream-flow design facilitates the formation of a high concentration of microbial beds, increasing the surface area in contact with wastewater, and thus improving treatment efficiency.
Methane fermentation: The organic matter in the wastewater is converted into methane, a combustible gas that can be used as an energy source, and carbon dioxide, which is released into the atmosphere.
Sedimentation and separation: There is a sedimentation zone in the upper part of the reactor, and microorganisms precipitate in the sedimentation zone to form a relatively dense sludge layer. This prevents microorganisms from spilling out with the treated wastewater and ensures a clear effluent.
In order to meet higher environmental standards, the effluent needs to undergo advanced treatment processes, such as oxidation and filtration, to ensure that the effluent COD concentration meets the current environmental requirements.