How is urea wastewater generally treated?
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How is urea wastewater generally treated?
..Biological hydrolysis---Ammonia stripping recovery---Biological treatment of effluent
First, determine the quality parameters of the urea wastewater, such as the ammonia nitrogen content and urea content in the urea solution; in particular, the urea content is important (as its concentration is very high after biological hydrolysis, and the ammonia nitrogen concentration can be calculated directly through material balance). Is there wastewater from the ammonia synthesis process included in this urea wastewater? For the stripping process on the upper floor, how is it carried out? Is it by adjusting the pH value before stripping, or by using an ammonia evaporation process? What happens in terms of biochemical treatment later on? If it’s simply ammonia-nitrogen wastewater, how can the effectiveness of biochemical treatment be ensured?
Generally, it starts with in-depth analysis, followed by stripping, and finally nitrification and denitrification treatment using biochemical methods
After in-depth treatment, the ammonia nitrogen content in the wastewater is reduced; subsequent alkali stripping is carried out to reach a certain concentration, after which nitrifying and denitrifying bacteria are used for further treatment.
Pre-treatment is carried out using chemical agents; under acidic conditions, this is achieved by adding nitrogen removal agents, with carbon dioxide and nitrogen being the main products.
The process condensate from urea plants is generally treated using desorption and advanced hydrolysis techniques, resulting in wastewater with ammonia and urea levels of less than 5 ppm. This wastewater is then sent to demineralized water for recovery, or used as feedwater for the low-pressure waste boilers in ammonia synthesis.
The most practical process is hydrolysis; this technology is well-developed. In such a hydrolysis tower, full or partial reflux is used to obtain gaseous ammonia at the top of the tower, while the concentration of ammonia in the water at the bottom of the tower can be kept below 5PPm.
Deep hydrolysis is used to break down urea in order to recover ammonia and carbon dioxide; the water resulting from this process is then sent to boilers for use.
For deep hydrolysis, the water obtained after treatment and sent to the desalinated water system presents the following problems: 1. How to address the high electrical conductivity of the water after deep hydrolysis? 2. The issue of oil in the water after deep hydrolysis. 3. What is the reason for the resin clumping together after recovery?
There is no mature treatment process yet! The ammonia nitrogen level is too high, the carbon content is insufficient, and mainly the treatment cost is too high! It is best to treat it in combination with other wastewater; many chemical wastewater streams require the addition of urea!
Reuse. Through deep hydrolysis, ammonia is distilled out; then chemicals are added to adjust the water quality, which is then reused in the gas generation jacket, with the water quality reaching the standards of refined softened water.
I’m not sure whether there are specialized facilities such as ammonia steaming or stripping in the production process; if not, alkali blowing should be considered first, followed by acidification and biochemical treatment. If hydrolysis is carried out first, the amount of acid and alkali required is too large, making it unsuitable for long-term operation… This is just my personal opinion
The process condensate from urea plants is generally treated using desorption and advanced hydrolysis techniques, resulting in wastewater with ammonia and urea levels of less than 5 ppm. This wastewater is then sent to demineralized water for recovery, or used as feedwater for the low-pressure waste boilers in ammonia synthesis. The most practical process is hydrolysis; this technology is well-developed. In such a hydrolysis tower, full or partial reflux is used to obtain gaseous ammonia at the top of the tower, while the concentration of ammonia in the water at the bottom of the tower can be kept below 5PPm.
Our company’s approach is to first carry out desorption, followed by ammonia stripping for recovery, then treat the resulting water through A/O biological treatment