The sedimentation process is used for separating sand and surface sludge from the water in rectangular basins. The sand and heavy solids that settle to the bottom are pumped out using a submersible pump hanging from the pump vacon or an air pump into the sand/water channel located next to the basin. The sand/water mixture flows through the channel into the pumping basin for pumping out for further processing. The same pump vacon scraper is used for scraping the sludge from the surface into the sludge collection channel and then delivered for further processing. The treated water is led out as overflow to the next part of the treatment process.