Waste water purification unit has sand and gravel filter and transparent cover acting as barrier to odours and allowing sunlight to pass through

摘要

The purification unit has a sand and gravel filter (24, 25, 26) and a removable cover (18) based on aluminium and polycarbonate to act as a barrier for odours and allows through at least part of the sun's rays. It has a system for circulating sir through the filter, incorporating a suction port (19) with a filter (31) at the top and a fan. The filter consists of a bottom layer (24) of gravel to drain away effluents and for aeration, and intermediate layer (25) of finer gravel for aeration and nitrification, and an upper layer (26) of sand for fixing bacteria. The ventilation takes place through pipes (27) linked to the space (32) under the cover and situated between the middle and upper filter layers.