APPLICATION OF HUMATE SUSTAINABLE ALTERNATIVE FOR REMEDIATION OF WASTEWATER AND GROUNDWATER

Transcription

1 APPLICATION OF HUMATE SUSTAINABLE ALTERNATIVE FOR REMEDIATION OF WASTEWATER AND GROUNDWATER Ewa Lipczynska-Kochany *) and Jan Kochany **) * ) Environmental Consultant, Mississauga, ON Canada **) Conestoga-Rovers & Associates, Mississauga, ON Canada

2 Introduction Humic substances (HS), products of transformation of organic residues of plants and animals by soil microorganisms, are important components of soil and natural waters. HS presence in potable water is undesirable, but its beneficial influence on remediation of soil and groundwater contaminated with metals and petroleum products has been reported. Until recently, an application of HS in the treatment of industrial wastewater has received less attention.

3 Scope 1. Laboratory studies - Effect of humate (HS) on: - biological (aerobic) treatment of an industrial wastewater contaminated with: diesel oil, formaldehyde, phenols, heavy metals, ammonia and phosphorus; - Fenton treatment of a coke plant wastewater conducted at ph = 3.5 and Pilot studies Biological treatment of groundwater contaminated with: NH 3 -N, SCN, CN, phenols and As with Fenton/HS pre-treatment at ph 7.0

4 Purpose of this Work Studies focused on a practical application of HS allowing reducing the concentration of the contaminants of concern before their discharge to the natural water bodies (or to the ground). There was no discharge limit for color.

5 Laboratory Studies Materials and Methods Wastewater samples were collected from a chemical plant, still mill, food processing plant and from coke plant. Diesel oil was from a local Shell gas station. Municipal sewage and returned activated sludge (RAS), used as biomass, were from a local treatment plant. Humate HS, highly oxidized lignite from NM used in these studies, contained approximately 20% of fulvic acid, 50% of humic acids and about 30% of insoluble matter.

6 Laboratory Studies Materials and Methods Aerobic respirometer: 12 channel (N-CON Systems). Measurements and interpretation of the biological oxygen consumption under well-defined experimental conditions are the basis of the aerobic respirometry. Based on results of respirometric (aerobic) measurements and chemical analysis, biokinetic data can be calculated using Monod model (for non-inhibitory wastes) or Haldane equation (for inhibitory wastes) [1].

7 Mitigation of an inhibitory effect of diesel oil Respirometric studies on sewage contaminated with diesel oil (0-10 g l -1 ) indicated a strong inhibitory effect on the biomass activity, and data complied with the Haldane model. Addition of HS (2 g l -1 ) to the sewage containing 10 g l -1 of oil resulted in almost complete recovery of the biomass. The system complied with the Monod model [1].

8 Mitigation of the RAS inhibition caused by diesel oil Haldane model - Inhibition RAS in sewage Monod model Inhibition removed by HS

9 Mitigation of an inhibitory effect of formaldehyde and phenol The industrial wastewater was contaminated with phenol (735 mgl -1 ) and formaldehyde (850 mgl -1 ). Initial respirometric tests demonstrated strong inhibition of biological activities. HS (2 g l -1 ) substantially reduced the inhibitory effect caused by the pollutants, enhanced the oxygen uptake and increased the removal of phenol and formaldehyde [2].

10 Removal (%) BOU (mg l -1 ) Effect of HS dose on BOU and phenol and formaldehyde removal Sewage/wastewater (60/40) Sewage Formaldehyde Phenol Humate dose (mg l -1 )

11 Mitigation of an inhibitory effect of heavy metals Inhibition of biological processes by heavy metals is known, but until recently means of the mitigation have not been explored. The studied still mill wastewater, containing heavy metals, was inhibitory to biomass, particularly to nitrifying bacteria. While COD removal was high (82%), only 7% of ammonia was oxidized to nitrate [3]. Addition of HS (500 mgl -1 ) removed this inhibition. Removal of ammonia and metals was 99% and over 90%, respectively [3].

12 Oxygen uptake (mg O 2 l -1 ) Effect of HS dose on biological oxygen uptake Humate dose (mg l -1 )

13 Concentration (mg l -1 ) Effect of HS dose on metals removal Chromium Copper Manganese Nickel Zinc Humate dose (mg l -1 )

14 Impact of HS on nitrification and metals removal Parameter Influent Effluent Effluent (wastewater) (no HS) (with HS, 500 mg l -1 ) (mg l -1 ) removed (%) (mg l -1 ) removed (%) SCOD 168± NH 3 -N NO 3 -N < *) *) Calcium < Chromium Copper Iron Manganese Nickel Zinc *) formed

15 Removal of ammonia and phosphorus Beneficial HS effect on ammonia and phosphorus removal was observed during the aerobic treatment of wastewater from a food processing plant. Wastewater contained inhibitors of nitrification. Biokinetics complied with the Haldane model. In the presence of HS (2 g l -1 ) the inhibition was mitigated and both ammonia and phosphorus were almost completely removed. Approximately 74% of ammonia was converted to nitrate, suggesting that nitrification was the main mechanism of the ammonia removal [4].

16 Concentration (mg l -1 ) Impact of HS on nitrification and T-P removal NH3-N NO3-N T-P 0 RAS only RAS/HS (1000 mg l-1) RAS/HS (2000 mg l-1) HS (2000 mg l-1)

17 Effect of HS on the Fenton treatment at ph 3.5 and ph 7.0 Heavy contaminated wastewater from a coke plant was treated with Fenton reagent: FeS0 4 (100 mg l -1 ) and H (200 mg l -1 ) Without HS, the removal of all contaminants was significantly higher at ph = 3.5 than at ph = 7.0 At ph = 7.0, the removal of all contaminants in the presence of HS (3gl -1 ) was comparable to that at ph 3.5 without HS [5].

18 Removal (%) Effect of HS on the Fenton treatment at ph = 3.5 and ph = Thiocyanate Cyanide Phenol ph=3.5 ph=3.5 HS ph=7.0 ph=7.0 HS HS dose 3,000 mg l -1 ; FeSO mg l -1 ; H 2 O mg l -1

19 Pilot Studies Biological (SBR) Groundwater Treatment Groundwater from a site of a former coke plant was contaminated with ammonia, hydrocarbons, thiocynate, phenols and arsenic. Biomass was collected from a coke wastewater treatment plant. To mitigate an inhibition of nitrification, Fenton/HS pre-treatment at ph 7.0 was applied.

20 Pilot Studies Biological (SBR) Groundwater Treatment Studies were conducted for 90 days. Samples were collected, analysed and treated every 10 days. Two SBR reactors; one fed with raw groundwater, another one with the supernatant from the Fenton pre-treatment. Fenton pre-treatment step: FeSO 4 (50 mg l -1 ), H 2 O 2 (150 mg l -1 ), HS (1 g l -1 ); ph not adjusted.

21 Pilot System Operation Fenton/HS HRT = 5 Days 3 cycles/day SBR1 Sludge Sludge SBR2 Sludge

22 Pilot Studies Biological treatment system

23 Concentration (mg l -1 ) Pilot Studies TOC, thiocyanate and phenols removal TOC Thiocyanate Phenols Raw Fenton Fenton/Biology Biology no Fenton

24 Concentration (mg l -1 ) Pilot Studies Nitrification NH3-N NO3-N Raw Fenton Fenton/Biology Biology no Fenton

25 Concentration (mg l -1 ) Pilot Studies Arsenic removal Raw Fenton Fenton/Biology Biology no Fenton

26 Pilot Studies Effect of Fenton/HS step on the biological treatment Parameter Raw Limit After Fenton/HS Effluent (Fenton) Effluent (no Fenton) (mg l -1 ) removed removed removed (%) (mg l -1 ) (%) (mg l -1 ) (%) COD Phenols NH 3 -N NO 3 -N Thiocyanate Cyanide Arsenic

27 Concentration (mg l -1 ) Pilot Studies Phenol and thiocyanate removal 250 Raw Phenol Thiocyanate 100 After Fenton Days of operation

28 Summary Presence of HS can be beneficial for chemical and biological treatment of industrial wastewater and groundwater. With HS, the efficiency of the Fenton treatment at neutral ph is similar to that at acidic conditions. HS mitigate inhibitory effects of organic substances and heavy metals on the activated sludge and they stimulate biological processes. HS enhance nitrification and phosphorus removal, increasing the content of nutrients in the wasted activated sludge.

29 References 1. Lipczynska-Kochany, E. and Kochany, J., Respirometric studies on the impact of humic substances on the activated sludge treatment: Mitigation of an inhibitory effect caused by diesel oil. Environ. Technol., 29, (2008). 2. Lipczynska-Kochany, E. and Kochany, J., Humic substances in bioremediation of industrial wastewater Mitigation of inhibition of activated sludge caused by phenol and formaldehyde, J. Environ. Sci. Health, Part A, 43, (2008). 3. Lipczynska-Kochany, E. and Kochany, J., Effect of humate on biological treatment of wastewater containing heavy metals, Chemosphere, 77, (2009). 4. Kochany, J. and Lipczynska-Kochany, E., Aerobic treatment of wastewater: Removal of nitrogen and phosphorus in the presence of humic substances. Environ. Technol., 30 (5) (2009). 5. Lipczynska-Kochany, E. and Kochany, J., Effect of humic substances on the Fenton treatment of wastewater at acidic and neutral ph, Chemosphere, 73, (2008).