NATURAL WASTEWATER TREATMENT  Pollutant removal by minimal energy utilisation and chemicals  Usage of natural processes (natural resources)  Low cost technology

Advantages: –Environmental friendly –Low construction, operation and maintenance costs –Low energy demand –No special skills are required for the operation –Acceptable operation among wide range of conditions (loads, etc.) –Can be constructed on otherwise „useless” areas –aesthetics –Able to treat diffuse pollutants

Disadvantages: –Large area requirement (long residence time) –Special requirements (topography, soil type) –Seasonal change in pollutant removal efficiency –Start-up period can be long –Construction problems can be hidden for long time

TERRESTRIAL SYSTEMS irrigation slow rate infiltration rapid infiltration root zone system (reed beds, subsurface flow wetlands)

AQUATIC SYSTEMS ponds, lagoons anaerobic facultative (aerobic-anaerobic) aerobic aerated fish ponds floating plant system free water surface wetland overland flow

RAPID INFILTRATION

SLOW RATE INFILTRARTION wastewater evaporation infiltration

POPLAR IRRIGATION

REED BEDS

REED BED

FREE-FLOATING PLANTS

OPERATIONAL PARAMETERS 0,14-1,6irrigation 0,6-3, Slow rate filtration Rapid infiltration 5,1-11,7(8,2)1,4-22,3(7) Free surface wetland 19,1(3,1)2,4(10) Free-floating 0,9-23,0(5)0,87-26,0(7,8)1-200 Reed bed SPECIFIC SURFACE m 2 /pe HIHYDRAULIC LOAD cm/dayCAPACITY m 3 /day TYPE

REMOVAL EFFICIENCIES Rapid infiltration 50(15-81)50(12-65)80(60-93)80(51-89) Free surface wetland 50(16-67)40(14-72)80(20-95)80(10-94) Free floating plant 40(11-94)40(10-88)80(60-98)80(51-95) Reed bed TNTPTSS BOd 5 Type