Among the numerous links in sewage treatment, sludge treatment is of vital importance, and sludge pressing and shaping is an extremely crucial step among them. However, in the actual production process, the problem of unformed sludge pressing occurs frequently, causing many troubles to the sewage treatment work. This issue not only makes it difficult to effectively dewater sludge, increasing the difficulty and cost of subsequent treatment, but also may pose a potential threat to the environment. So, how can we overcome this difficult problem? Numerous practices and studies have shown that sludge enhancers have become a powerful weapon to solve the problem of unformed sludge pressing.
Analysis of the Problem of Unformed Mud Pressing
The formation of sludge stems from the sewage treatment process. During this period, various water treatment chemical agents used make the composition of sludge extremely complex. From a microscopic perspective, sludge contains a large amount of colloidal particles, microbial aggregates, and high-viscosity substances, etc. These substances interweave with each other, forming a special structure. Colloidal particles, due to their electric charge, repel each other and are difficult to aggregate and settle. Microbial aggregates contain a large amount of extracellular polymers (EPS), which have strong hydrophilicity and tightly bind water, making the fluidity of sludge poor and difficult to be effectively compressed and formed. In addition, the presence of high-viscosity substances further increases the internal resistance of the sludge, making it difficult for water to be discharged smoothly during the filtration process, resulting in the sludge not being formed properly.
Taking a certain urban sewage treatment plant as an example, when the plant was dealing with the sludge produced by the mixture of domestic sewage and some industrial wastewater, it encountered a serious problem of unformed sludge pressing. Under the traditional treatment method, the sludge after filtration is in a loose and non-blocky state, with a moisture content of over 80%. It is not only difficult to transport but also prone to seepage of sewage, causing pollution to the surrounding environment. After analysis, it was found that the sludge contains a relatively high content of organic matter and microbial aggregates, which leads to extremely poor dewatering performance of the sludge.
The mechanism of action of sludge efficiency enhancers
Sludge enhancer, as a chemical agent specifically developed to address the challenges of sludge treatment, has a complex and sophisticated composition. Taking common sludge enhancers as an example, they mainly include inorganic compounds, sludge surface structure modifiers, degreasing agents, cell wall disruptors, sludge surface treatment agents, and sludge stripping agents, etc. These components work in synergy to improve the properties of sludge on multiple levels and facilitate sludge pressing and shaping.
Sludge surface structure modifiers can change the surface properties of sludge particles. When the sludge enhancer is not used, the surface of the sludge particles is uneven, with numerous gaps and channels. A large amount of water exists in it, increasing the specific resistance of the sludge and being unfavorable for dewatering. Surface structure modifiers can make the surface of sludge particles smooth, reduce channels and gaps, lower specific resistance, and make it easier for water to be discharged. The cell wall disruptor launches an "attack" on the microbial cells in the sludge. Microbial cells contain a large amount of bound water, which is difficult to remove by conventional methods. Cell wall disruptors can destroy the cell walls and cell membranes of microbial cells, releasing the water inside the cells and converting it into free water, which can then be effectively separated in the subsequent filtration process. Degreasing agents can remove oily substances from sludge, reduce the coating of oil on sludge particles, enhance the interaction between sludge particles, and promote their aggregation and sedimentation.
When the sludge enhancer is thoroughly mixed with the sludge, through a series of physical and chemical actions, it alters the microstructure and macroscopic properties of the sludge. The originally difficult-to-handle sludge, under the action of sludge enhancers, has a looser structure, enhanced fluidity, and water can be more easily squeezed out, creating favorable conditions for sludge pressing and shaping.
The practical application effect is remarkable
In practical applications, sludge enhancers have demonstrated outstanding effects in addressing the issue of unformed sludge during pressing. The sludge produced by a certain industrial wastewater treatment plant contains a large amount of organic matter and colloidal substances, and sludge pressing has always been a difficult problem. After the adoption of the sludge enhancer, the situation has been greatly improved. The factory adds an appropriate amount of sludge enhancer to the sludge conditioning tank. After thorough stirring and mixing, the sludge is conveyed to the plate and frame filter press. Before using the sludge enhancer, it was difficult to feed the filter press, with a feeding time of up to 4 hours. Moreover, the sludge after filtration was not formed and had a moisture content as high as 85%. After using the sludge enhancer, the feeding speed was significantly accelerated, and the feeding time was shortened to 2.5 hours. The sludge after pressure filtration could form a solid mud cake, and the moisture content was reduced to below 60%. Not only did it solve the problem of unformed mud pressing, but it also greatly improved production efficiency and reduced the cost of subsequent processing.
When using sludge enhancers to solve the problem of unformed sludge pressing, there are several points that need special attention. The first issue is the selection. As the properties of sludge are influenced by various factors such as the source of sewage, the sewage treatment process, and the chemicals used, the properties of different sludges vary significantly. Therefore, when choosing a sludge enhancer, it is necessary to conduct experiments and selection based on the specific properties of the sludge to ensure that the selected sludge enhancer is fully compatible with the sludge and can achieve the best effect.
The second is the determination of the dosage. Excessive dosage not only leads to waste of chemicals and increases treatment costs, but may also have adverse effects on subsequent treatments. If the dosage is too small, the expected treatment effect cannot be achieved. Generally speaking, it is necessary to first determine a rough dosage range through small-scale tests, and then conduct pilot-scale tests to further optimize the dosage, so as to achieve the best treatment effect and cost-benefit balance.
In addition, sludge enhancers usually need to be used in conjunction with appropriate filter press equipment. Take the plate and frame filter press as an example. After using the sludge enhancer, some parameters of the filter press need to be appropriately adjusted, such as the feeding pressure and the pressing time, to give full play to the role of the enhancer and achieve a better sludge pressing and shaping effect.
Sludge enhancers provide an effective solution to the problem of unformed sludge during sludge pressing. By altering the physical and chemical properties of sludge, sludge enhancers can make the originally difficult sludge easier to handle, achieve efficient sludge pressing and dewatering, and provide strong support for the stable operation and sustainable development of the sewage treatment industry. In the future, with the continuous advancement of technology and the accumulation of application experience, sludge enhancers are expected to play a greater role in the field of sludge treatment.