Innovative Treatment of Combined Sewer Overflow and perspective of Hydrochar reuse for pollutants adsorption

Transcription

1 Innovative Treatment of Combined Sewer Overflow and perspective of Hydrochar reuse for pollutants adsorption A. Botturi a* ; N. Frison a ; C. Giosuè b ; A. L. Eusebi b ; F. Merzari c ; L. Fiori c ; F. Fatone b a University of Verona, Department of Biotechnology b Marche Polytechnic University, Department of Materials, Enivironmental Sciences and Urban Planning SIMAU c University of Trento, Department of Civil, Environmental and Mechanical Engineering

2 Combined Sewer Overflows: pressure and impacts o ORGANIC MATTER o SOLID MATTERS SUCH AS MACRO AND MICRO PARTICLES o CHEMICALS (N, P, HEAVY METALS ) o PATHOGENS o Bathing and Recreational water use o Water and food consumption o Water uses for agricultural activities o Eutrophication o Biodiversity o Morphology Land Urban area CHANGE OF QUALITY OF THE RECEIVING WATER BODY Runoff Combined Sewer System 650,000 CSOs stations in Europe (EurEau) 20% of surface water is at serious risk from pollution (EU Water Framework Directive, WFD)

3 Typical CSOs treatment PRELIMINARY DEGRITTING FOR SOLIDS REMOVAL

4 The INTCATCH Project Granular activated carbon adsorption to remove solids and contaminants Dynamic rotating filtration to remove solids UV disinfection to remove pathogens

5 Advanced treatment: Granular Activated Carbon (GAC) Filtration o o o o o The most applied adsorption technique for the treatment of wastewater No real information about CSO water treatment Used to absorb natural organic compounds and chemicals by both chemical and physical absorption From organic materials with high carbon contents (wood, lignite, coal) Diameter ranging between mm

6 Hydrochar: production and uses T=190, 250 P=140 bar 400 g digesteddewaterd sludge g digested sludge HYDROCHAR: o Fuel o Soil amendment o Absorbent for activated carbon production

7 Characteristics of GAC tested NAME ST 300 ST 300 STW 400 STW 400 ST 100 TYPE Mineral GAC Mineral GAC Mineral GAC Mineral GAC Mineral GAC SIZE 8x30 12x40 8x30 12x40 8x30 DISTRIBUTIO N [U.S. mesh] DENSITY [g/l] 500±20 500±20 500±20 500±20 520±20 UMIDITY [%] <2 <2 <2 <2 <2 IODINE >950 >950 >1000 >1000 >750 NUMBER [mg/l] METHYLENE >180 >180 >190 >190 >150 BLUE INDEX [mg/l] ABRASION NUMBER [%] > 80 > 80 > 80 > 80 > 80 HARDNESS [%] ASH LEVEL [%] SURFACE AREA [m 2 /g] > 90 > 90 > 90 > 90 > 90 < 15 < 15 < 15 < 15 < 15 > 950 > 950 > 1000 > 1000 > 800

8 Granulometric and spectroscopy analysis GAC type C u ST100 8X ST300 8X ST300 12X STW400 8X STW400 12X mm in diameter Scanning Electron Microscope

9 Results: GAC perforance Test GAC o Wastewater (30 mg scod/l) o Absorbent: commercial GAC o Quantity: 2, 5, 10, 20 g/l ST100 8x30 Best performance in scod removal ST300 8x30 Best performance observed in the removal of Mn and Cd (80%) and Cr (40%) ST100 8x30, ST300 8x30 used in CSOs Pilot Plant in real environment E% CODs x/m 90,0 80,0 70,0 60,0 50,0 40,0 30,0 20,0 10,0 0, Dose (g/l) ST 300 8X30 ST X40 STW 400 8X30 STW X40 ST 100 8X30 16,0 14,0 12,0 10,0 8,0 6,0 4,0 2,0 0, Dose (g/l) ST 300 8X30 ST X40 STW 400 8X30 STW X40 ST 100 8X30

10 Hydrochar analysis g HC/g feedstock g HC/g feedstock Raw HC190 Raw HC250 Washed HC190 Washed HC250 EDS microanalysis (wt%) Zn Mn Na Al Si P S K Ca Fe HC 250 HC micron in diameter

11 Preliminary results: raw and washed HC 800 Test 0_A_HC o Distilled water o Absorbent: raw HC o Quantity: 5 and 0.5 g/l o Analysis: scod profile mg scod/l Time (min) HC g/L HC250 5g/L HC g/L HC190 5g/L Test 0_B_HC o Distilled water o Absorbent: washed HC o Quantity: 5 and 0.5 g/l o Analysis: scod profile mg scod/l Time (min) HC g/L HC250 5g/L HC g/L HC190 5g/L

12 scod removal efficiency of washed HC Test 1_HC o Wastewater (200 mg scod/l) o Absorbent: washed HC o Quantity: 5 and 0.5 g/l E% scod Time (min) HC g/L HC250 5g/L HC g/L HC190 5g/L Test 2_HC o CSO water (30 mg scod/l) o Absorbent: washed HC o Quantity: 5 and 0.5 g/l NO LEVEL OF ABSORPTION IN TERMS OF scod

13 Metals profile with washed HC Test 3_HC o Distilled water o Absorbent: washed HC o Quantity: 0.5 g/l o Metal added: Mn 2 and 15 mg/l Test 3_HC 16,000 14,000 12,000 mg/l 10,000 8,000 6,000 4,000 2,000 0, Time (min) Mn 190_02 Mn 250_02 Mn 190_15 Mn 250_15

14 Conclusion and future outlook o Higher scod removal efficiency observed at lower concentration of HC (0.5 g/l) and higher concentration of scod/metals o Optimal washing ratio of 0.5 g of absorbent for each L of washing water o Slight removal of Mn detected o Further experiments are need to investigate more in detail the activated and nonactivated HC

15 Innovative Treatment of Combined Sewer Overflow and perspective of Hydrochar reuse for pollutants adsorption Thank you Alice Botturi