Replacing sedimentation tanks with hydrolysis tanks

It’s not possible to generalize everything. Our factory installed a hydrolysis unit, primarily used for treating phenol-containing wastewater – first through hydrolysis and then in an SBR process. It cost tens of millions, yet the hydrolysis unit was essentially useless; it even reduced the processing capacity of the SBR system. I think every craft has its strengths; the key is to use it in the right place.

I think this is inappropriate; it doesn’t make sense from a principle standpoint. The primary sedimentation tank can be used for separating sludge from water. And the hydrolysis tank is used for hydrolysis. If wastewater containing chemical sludge enters the hydrolysis tank, it will certainly affect the hydrolysis process. Moreover, over time, the hydrolysis tank will turn into a sludge tank. . . . The feasibility is not very good, and it also depends on the type of hydrolysis tank, among other factors. . . .

This term generally refers to the treatment of domestic wastewater, and there is some truth to that. After primary sedimentation, a shortage of carbon source may occur in subsequent stages. As for industrial wastewater, it can’t be discussed in general terms

Different types of wastewater require different treatment methods suited to them; the original poster’s view is too simplistic. For processes such as nickel plating and chromium plating, hydrolysis tanks can by no means replace sedimentation tanks.

Replacing the sedimentation tank with a hydrolysis tank is not reasonable in principle; sedimentation tanks are used for separating sludge from water, while hydrolysis tanks are used for hydrolysis. When chemical sludge wastewater enters the hydrolysis tank, it will certainly affect the hydrolysis process; over time, the hydrolysis tank turns into a sludge tank. . . .

The advantages and disadvantages depend on the quality of the water entering the system. Function of the hydrolysis-acidification tank: Hydrolysis-acidification is primarily used in wastewater treatment processes where the concentration of organic matter and SS is high; it is a relatively important treatment process. When the organic substances in water have complex structures, hydrolytic acidifying bacteria use the H+ and -OH ions produced by the ionization of H2O to break the C-C bonds in these organic molecules. By adding H+ to one end and -OH to the other, they can convert long chains into shorter ones, branch structures into straight chains, and cyclic structures into straight or branched chains, thereby improving the biodegradability of the wastewater. When the SS concentration in water is high, hydrolytic bacteria capture it using their extracellular membranes, then hydrolyze it into molecular fragments with external enzymes before taking it into the cell for metabolism. This incomplete metabolism converts SS into soluble organic matter, resulting in clearer effluent. During this process, hydrolytic bacteria utilize the bond energy of organic compounds with broken bonds to carry out their biological activities. However, COD may not necessarily change on the surface; this depends on the parameters chosen during design as well as the properties of the organic matter in the wastewater. Long-term operational control allows the microorganisms to produce induced enzymes for the targeted breakdown of organic matter, which is one of the reasons why the treatment efficiency improves gradually after proper process control is established during the commissioning phase. The hydrolysis process is not simple; when designing it, it is necessary to consider the properties of the organic substances in the wastewater in order to determine the appropriate design parameters for hydrolysis, including the hydrolysis retention time, mixing methods, circulation methods, sludge return methods, design load, acidity level of the effluent, sludge degradation capacity, and the processes required as follow-ups. Primary sedimentation tank: Its main functions are to remove 50-60% of the suspended solids SS, to reduce the BOD5 level in wastewater by 25-35%, and to eliminate floating substances, all of which contribute to improving water quality. In terms of their functions and roles, they are different: hydrolysis acidification primarily involves the conversion of large organic molecules into smaller ones, thereby simplifying and facilitating subsequent treatment processes. On the other hand, the primary sedimentation tank is used mainly for removing suspended solids; if the level of suspended solids in the wastewater is high, it can affect the proper operation of biochemical treatment processes. By precipitating a portion of these suspended solids, it also reduces the difficulty of subsequent treatment. Their designed hydraulic retention times also differ; the former generally requires 4-6 hours, while sedimentation usually takes 2-3 hours. Their biological requirements also differ; the former generally requires operation under aerobic and agitated conditions, while sedimentation does not need these. In short, there are differences, but there are also aspects where they are similar; therefore, a hydrolysis tank can sometimes replace a primary sedimentation tank, and other times it cannot – it depends on the specific circumstances.