A multi-phase separation system for liquids with dissolved solids and/or liquid/solid mixtures. The separation system can include four phases. One of the phases can include a crossflow filtration unit. The crossflow filtration unit can separate solids from the process fluid by flowing the process fluid in a crossflow orientation over a filter screen. The crossflow filtration unit can be drained of process fluid and cleaned by high pressure cleaning nozzles. The crossflow filtration unit can be configured to simplify or reduce the cost of downstream filtration phases. The phases may be used selectively and/or may be outfitted with various components to meet different system requirements.