In swimming pool enzyme clarifiers, the ability of cellulase to penetrate and degrade the biofilm on the pool wall is a key factor affecting water purification efficiency. Biofilms, as complex structures formed by microorganisms on the pool wall surface, have physicochemical properties that directly influence enzyme activity. Cellulase must penetrate barriers such as the mucus layer, microbial community, and extracellular polymeric substances (EPS) of the biofilm to access and degrade the cellulose components. This process is regulated by multiple factors, including the microstructure of the biofilm, enzyme molecular characteristics, environmental conditions, and the chemical composition of the water.
The microstructure of the biofilm is fundamental to determining the penetration efficiency of cellulase. Mature biofilms typically exhibit a multi-layered heterogeneous structure, with an outer layer dominated by loose EPS and an inner layer composed of dense microbial cells and protein networks. This layered structure hinders the diffusion of enzyme molecules, especially the penetration of large cellulase molecules. If the biofilm has a high cellulose content, such as from algae, bacterial capsules, or shed organic debris, enzyme molecules must preferentially degrade these high-density areas before further penetration. Furthermore, the porosity, surface roughness, and thickness of the biofilm also affect the enzyme's contact area and diffusion path. Thicker biofilms often require longer enzyme interaction times or higher enzyme concentrations to achieve effective degradation.
The molecular characteristics of cellulase directly influence its permeation and degradation capabilities. The enzyme's molecular weight, charge distribution, and conformational stability determine its ability to cross the physical barrier of the biofilm. Smaller molecular weight enzymes penetrate the pores of the biofilm more easily, while larger molecular weight enzymes may be trapped in the outer layer. The electrostatic interaction between the enzyme's surface charge and biofilm components also affects its adsorption-release balance. If the enzyme and the surface of EPS or microbial cells carry the same charge, electrostatic repulsion may reduce permeation efficiency. In addition, the conformational flexibility of the enzyme affects its binding ability to the substrate. In the complex environment of the biofilm, the enzyme must maintain its active conformation to effectively degrade cellulose.
Environmental conditions have a significant regulatory effect on enzyme-biofilm interactions. Temperature alters degradation efficiency by affecting the catalytic activity of the enzyme and the physical state of the biofilm. At suitable temperatures, enzyme activity increases and biofilm viscosity decreases, facilitating enzyme diffusion. Conversely, low or high temperatures may lead to enzyme inactivation or biofilm hardening, hindering permeation. pH is equally crucial, affecting not only the enzyme's charge properties and catalytic center state but also altering the degree of EPS dissociation in the biofilm, thereby regulating the enzyme's binding capacity to substrates. For example, an acidic environment may promote the activity of certain enzymes, but excessive acidification can damage the biofilm structure, leading to enzyme loss.
The chemical composition of water has a complex impact on enzyme degradation. Pool water often contains disinfectants such as chlorine and ozone, which may alter the structure of the enzyme's active site through oxidation or covalent modification, reducing its degradation capacity. Simultaneously, metal ions in the water, such as calcium and magnesium, may bind to enzymes or biofilm components, forming complexes or precipitates that hinder enzyme permeation. Furthermore, organic matter in the water, such as urea and amino acids, may competitively bind to enzyme molecules or serve as a nutrient source for microorganisms, promoting biofilm growth and indirectly weakening enzyme degradation.
Microbial community composition and metabolic activity also affect enzyme permeation and degradation. The components of EPS secreted by different microorganisms in biofilms vary. Polysaccharides produced by some bacteria may be more easily degraded by cellulases, while the metabolic products of other microorganisms may inhibit enzyme activity. Furthermore, the metabolic state of microorganisms, such as growth rate and spore formation, can alter the physical structure of the biofilm. For example, actively growing microorganisms may secrete more EPS, increasing the biofilm's density and thus hindering enzyme penetration.
The method of use and operating conditions of the enzyme clarifier directly affect its effectiveness. Too low a concentration may result in insufficient enzyme molecules to penetrate the biofilm, while too high a concentration may reduce the activity of individual enzyme units due to competitive adsorption between enzyme molecules. The method of addition, such as single-dose versus batch addition, also affects the distribution of enzymes in the biofilm; batch addition helps maintain continuous enzyme penetration. In addition, the circulating water flow rate affects the enzyme adsorption-removal balance by altering the shear force on the biofilm surface. Appropriate water flow can promote enzyme contact with the biofilm, but excessive shear force may lead to enzyme loss.
The ability of cellulase in pool enzyme clarifiers to penetrate and degrade pool wall biofilms is regulated by multiple factors, including biofilm structure, enzyme molecular characteristics, environmental conditions, water chemical composition, microbial community, and operating conditions. Understanding the interaction mechanisms of these factors helps optimize the formulation and usage strategies of enzyme clarifiers. For example, by adjusting the enzyme's molecular design, controlling water pH and temperature, and optimizing the dosing method, the degradation efficiency of biofilms can be improved, thereby more effectively improving pool water quality.
