Abstract: An air purification system for purifying polluted air includes a scrubber in which a pollutant in the polluted air is transferred to a scrubber liquid. A biological treatment unit includes at least one substantially flat substrate to support a microorganism population to remove the transferred pollutant from the scrubber liquid when the scrubber liquid with the transferred pollutant is distributed on the substrate. A plane of the substrate is substantially parallel to a direction of flow of the air from the scrubber.

Abstract: A system for treatment of collected waste comprises a waste receiving pit; at least one first separator for separating between first waste material having a specific gravity equal or less than that of water and second waste material having a specific gravity above that of water; at least one crusher for receiving said first waste material, substantially crushing at least a particulate portion thereof to a smaller particulate form to obtain treated waste material and producing a liquid product comprising water carrying the treated waste material; at least one acetogenic fermentor for receiving said liquid product and for anaerobic acetogenic fermentation thereof to produce a first fermented effluent; at least one methanogenic fermentor for receiving said first fermented effluent and for anaerobic methanogenic fermentation thereof to produce a second fermented effluent; at least one liquid feed line for feeding at least one of said first or said second effluent into one or more of the system's devices for