Which type of system could effectively remove hazardous substances from water?

A filtration system is designed to physically remove contaminants, including hazardous substances, from water by passing it through a barrier that captures particles and impurities. This method utilizes various types of filters, such as activated carbon, sand, membranes, or other materials that can trap different contaminants based on their size and chemical properties. Filtration systems are versatile and can be tailored to target specific hazardous substances, making them highly effective in treating water that may be polluted.

In contrast, a purification system, while aimed at making water safe for consumption, often employs various processes that may not solely focus on removing hazardous substances but might also involve chemical treatments or disinfection methods rather than physical removal. A softening system is specifically designed to reduce hardness caused by minerals like calcium and magnesium and does not typically address hazardous substances. Meanwhile, a hydroponic system is primarily intended for growing plants in nutrient solutions rather than treating or removing contaminants from water.

Thus, the effectiveness of a filtration system in specifically targeting and removing a wide range of hazardous substances makes it the most suitable choice in this context.