## 1 Introduction
MB exhibits redox properties and can react with biological organisms, organic compounds, and metal ions in water, thereby altering key water quality parameters such as color, odor, and biochemical oxygen demand (BOD). If discharged without proper treatment, MB poses serious risks to both environmental and human health. Due to increasing water pollution, _E. coli_ has become one of the primary contaminants in water bodies [21]. It can enter the environment through fecal discharge and other pathways. However, it is often accompanied by various other pathogens, posing significant risks to both human health and the ecological environment. Globally, _E. coli_ contamination in water bodies is a widespread concern. According to a report by the World Health Organization (WHO), approximately 80% of diseases in developing countries are associated with unsafe drinking water and poor sanitation, with _E. coli_ contamination being a major contributing factor. In many underdeveloped regions of Africa and Asia, the lack of adequate sewage treatment facilities and clean water supplies has resulted in frequent cases of _E. coli_ exceeding safe levels in rivers, lakes, groundwater, and other water sources [22]. Even in countries with relatively advanced sewage treatment systems, _E. coli_ contamination in water bodies remains a recurring issue. Common sources include agricultural non-point source pollution and the discharge of livestock and poultry waste. Therefore, addressing _E. coli_ contamination is a critical aspect of wastewater treatment, essential for ensuring water safety and public health. Municipal sludge (MS) is a solid waste generated during the sewage treatment process. The inorganic substances in MS are mainly oxides of silicon, iron, aluminum, and calcium. Its composition is relatively complex, containing a variety of inorganic substances, organic substances, and microorganisms. The organic components in MS primarily include carbohydrates, proteins, fats, and humic acids, which originate from plant matter in sewage, microbial biomass, and organic waste generated by human activities. These organic substances are rich in functional groups such as -OH, -COOH, -NH\({}_{2}\), and C=O, which exhibit strong coordination capabilities. As a result, they can readily form complexes with heavy metal ions, making MS highly effective for the removal of heavy metal ions from wastewater [23]. [PERSON] et al. prepared alkaline sludge biochar from septic tank sludge as a sustainable adsorbent for phosphorus recovery in agriculture [24]. First, the septic tank sludge was pyrolyzed at 500 \({}^{\circ}\)C to produce the original biochar, and then the basic biochar was prepared by the mixed pyrolysis of KOH and the original biochar at 800 \({}^{\circ}\)C. This kind of biochar preparation process is simple, but requires a higher temperature to pyrolyze the sludge, increasing the production cost. Therefore, we prepare a multifunctional adsorbent, by making full use of MS's rich functional groups, without pyrolysis, which can remove a variety of pollutants in the water body (radioactive elements, fluoride, dyes, and bacteria, etc. ), so as to cope with different pollutants in the water body and realize the process of wastewater purification. The biggest advantage of the adsorbent is that it not only realizes the resource utilization of MS, but also the prepared multifunctional adsorbent can better cope with the complex sewage environment. In response to the escalating issue of water pollution, we utilize the abundant functional groups present in the organic matter on the surface of MS to synthesize an adsorbent which is capable of effectively treating high-fluorine uranium-containing wastewater. In this study, cinnamaldehyde (CID) is incorporated to enhance the antibacterial properties of the composite against _E. coli_ in water. Additionally, zirconium dioxide (ZrO\({}_{2}\)) nanoparticles are loaded onto the material through a biomineralization process (Figure 1).