The researchers studied how to improve the removal of solid particles from wastewater to meet environmental standards and promote reuse. They tested a quadruple media filter at a sewage works, adjusting factors like flow rate and pH. They found that higher flow rates reduced solid removal efficiency, but using multiple media layers helped. Most particles were caught in the top layer of the filter, with deeper layers not adding much benefit. They also developed a new method to measure the shape of filter media grains accurately. Adjusting operational conditions and using different media materials can improve the performance of wastewater treatment filters.