Treatment of gasification wastewater

It can’t be called good! It’s barely manageable; the SBR (Activated Sludge Process) is used for treatment. There is an acidification and hydrolysis tank ahead, and after the SBR stage, the effluent is treated with strong oxidizing agents, which yields decent results – the final effluent meets the standards (**Class 3 discharge standards**). However, the cost is high; treating one batch of water can cost over 30 yuan. The plant is capable of treating around 1,800 tons of wastewater per day, but its stability is poor, with performance fluctuating from time to time. This remains one of the bottlenecks for our factory. The gasifier uses a Lurgi furnace. If anyone has a better way to handle this, please share it.

The wastewater treatment process for gasification is related to the type of gasifier used; varying exit temperatures of different gasifiers, different ways in which the feedstock and gasifying agent come into contact, and differences in temperature within the reaction zone all contribute to variations in the concentration and composition of pollutants in the gasification wastewater. Ammonia is generally present in pulmonary wastewater, so its treatment is complex and requires significant investment; there is yet no effective method to achieve \"zero emissions\". As for other impurities, specific circumstances need to be taken into account; there is no one-size-fits-all approach.

For the Lurgi furnace, pre-treatment before biochemical treatment is crucial. Extraction for phenol removal and ammonia evaporation can eliminate most pollutants, thereby reducing the load on the biochemical treatment stage significantly. At present, many manufacturers still use the old diisopropyl ether process for wastewater pre-treatment when choosing Lurgi furnaces; this process does not yield satisfactory extraction results, and there is significant loss of ether due to volatilization. In some factories, the ether loss per ton of water can reach 0.5 kilograms. The corresponding acid removal and ammonia evaporation processes are also relatively outdated. Overall, these methods have the following disadvantages: 1. Excessively high pH during extraction – Phenol is a weak acid, and when the pH exceeds 7.5, the extraction efficiency of phenol by almost all solvents decreases. This is the main reason for the low defoaming capacity of most processes nowadays. 2. The removal capacity for polyphenols is low. Polyphenols account for about half of the total phenol content, and the extraction agents commonly used today, such as diisopropyl ether, have a low distribution coefficient for polyphenols. This is also an important reason for the low defoaming ability. 3. The ammonia-rich gas obtained contains a high level of phenols; this high phenol content increases the load on the subsequent ammonia purification processes, and in some cases, the ammonia-rich gas produced must be burned away. 4. The design for acid removal and ammonia removal is unreasonable; acidic gases such as H2S and CO2, along with ammonia, undergo weak ionization in water, resulting in an ionic interaction between them. Most of the existing processes fail to effectively reduce this ionization effect, resulting in high costs for the removal of acidic gases and ammonia, and in some cases, incomplete removal. This leads to problems in the subsequent biochemical treatment stages, or severe scaling of inorganic substances in the process equipment. If there are manufacturers facing similar problems, feel free to post here; let’s discuss it together.

Our plant uses the IC process, namely sequential batch activated sludge method, to treat gasification wastewater

This type of wastewater is considered one of the most difficult to treat in the world. With **energy shortages, China has begun to develop coal-to-gas projects on a large scale; the largest such project at present is one in Keqi, Inner Mongolia, which produces 4 billion cubic meters of natural gas per year. After reviewing the literature, it was found that the treatment processes for this type of wastewater are as follows: Pretreatment (air flotation, sedimentation, etc.) – Biological treatment (this is the key stage; most research institutions use patented technologies that have been tested over many years and are capable of withstanding shock loads, or improved versions of such patented technologies. Ordinary biological treatment methods lack sufficient resistance to shock loads and flexibility in adjustment; readers interested in this topic can consult patents related to wastewater treatment in the coking industry) – Advanced treatment

Are different products resulting from different gasification purposes subject to different treatment processes?

A stripping tower can be used to separate the gases inside

I. Typical properties of gasification water: 1. High COD, high ammonia nitrogen, presence of phenols and sulfur, and a large amount of hard-to-degrade organic substances； 2. Difficult-to-degrade organic compounds mainly include phenols, quinolines, pyridines, indoles, furans, piperazines, acridines, imidazoles, long-chain alkanes, cycloalkanes, benzene, biphenyls, halogenated alkanes, as well as small amounts of alcohols, acids, and esters. Among these, alkylphenols, phthalic acids (esters), pyridines, etc., are all considered environmental endocrine disruptors or environmental hormones. 3. Detailed quantities of various types: Type of organic compound Quantity Type of organic compound Quantity Type of organic compound Quantity Phenols 13 Pyridines and imidazoles 3 Cyclohydrocarbons 4 Quinolines 6 Similar compounds 2 Benzene derivatives 10 Pyridines 3 Alcohols 2 Naphthalene 1 Indoles 3 Acids 3 Amines 9 Furan derivatives 4 Esters 4 Halogenated compounds 5 Piperazines and ** compounds 12 Long-chain alkanes 13

II. Treatment Process 1. Flotation, chemical dosing for sedimentation, ammonia removal (ammonia evaporation or stripping)； 2. Catalytic oxidation (ozone oxidation, ozone + ultraviolet light, hydrogen peroxide, etc.) – this step is the most crucial, as it directly determines the effectiveness of the subsequent biochemical treatment ； Moreover, the oxidation cost is high, which is key to optimizing the design ； 3. The biochemical system generally uses the A2/O process, namely hydrolysis acidification, anaerobic + aerobic stages. In most practical applications, water is added for dilution, and phosphates are added if necessary to adjust the C, N, P ratios. 4. Based on my experience in design and debugging, there are two areas that require effort. A. Combine treatment with domestic wastewater or other industrial wastewater, and optimize the system design to reduce treatment costs. B. Research, implement, and optimize physical and chemical treatment methods to create better conditions for biochemical degradation.

I’m a complete beginner, here to learn *.;P;P;P;P