The document discusses small wastewater treatment plants from Delphin Water Systems. It describes the company's use of fixed-bed technology for biological wastewater treatment, which allows the plants to efficiently treat variations in water loads. The document lists several plant models - Classic M+, L, XL, XL+, and XXL - and their capacities. It also describes the Combi Line modular system and Clean Box disinfection units for water reuse.