PAC TREATEMTN FOR VARIOUS CONTAMINANTS AT RMTPPAC TREATMENT FOR VARIOUS CONTAMINANTS AT RMTP
Ying Hong, Paul Rossman, Haishan Piao, Jim Springer Greater Cincinnati Water Works OAWWA 2020, Cincinnati OH
Ohio River Spills
Fuel Oil 25%
• ~80% spills are petroleum products
In Jan 2014, ten thousand gallons of MCHM leaked into the Kanawha River.
In Jan 1988, three million gallons of diesel oil spilled on the Monongahela River upstream of Pittsburgh.
Sheet1
Coal
Petrol
Chem
Other
Total
Upstream
1986
947
2835
0
5768
Downstream
35869
4040
774
0
40683
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
Meldahl
35835
35433
41021
42265
46087
46049
48387
46943
53092
58024
58349
Gasoline
6.5
Sheet2
Meldahl
Kilotons
6.5
3
1
0.75
0.5
0.1
Sheet3
Gasoline
• Ohio River Bloom August-Oct 2015. Stretched about 700 miles long.
• Affected GCWW from Sept- early Oct. Cyanotoxins detected in raw water.
Upstream, 9/9/2015 GCWW Intake, 9/16/2015
Inline-reservoirs (after coagulation) 9/2015
• Ohio EPA HAB rule in 2016. Microcystins action level of 0.3 µg/L.
• Another HAB episode in 2019. Cyanotoxins detected in raw water.
GCWW Intake
Inline-reservoirs (after coagulation)
• Increase coagulant dose
• Lower sand filtration rate
• Increase chlorine dose and disinfect at a
lower pH
Rated capacity 240 mgd
T&O Issues Caused by Algal Blooms
Algae speciation and associated WQ issues are different between HAB and T&O causing algal blooms:
Microcystis
Algae toxins Microcystins No toxins detected
T&O compounds No MIB or Geosmin
Bloom seasons Summer-Fall All year, particularly in spring
Other WQ issues Increase turbidity and decrease run hour
Increase turbidity and decrease run hour
Regulation Ohio HAB rule No
Limnothrix Anabaena
Pseudanabaena Aphanizomenon
Question 1
What are the major issues caused by algal blooms in your facilities: a. Algal toxins b. T&O compounds c. Filter run hours and turbidity d. Others e. No algae issues
Tested PACs
Min. Iodine mg/g
OxPure AQM 325
*Carbpure 800, 800F,
WPH1000 90%<44um 0.4-0.75 1000
River Spills
Algal Toxins
Contact Time (hr)
Raw water ~0.5 15-800 3-4 7.8-8.0 Medium 200 River only
Inline Reservoirs
Secondary Sedimentation Basins
Experimental Goals and Plan
Goals: Identify the best performing PAC for all contaminants, if possible Identity the best location for PAC application at RMTP
Bench Testing Experimental Plan: Water samples collected at raw water, reservoirs and secondary settling basins Spike Benzene &TCE @10 ppb, Microcystins @20 ppb, and MIB @50 ppt Test PAC doses at 50lb/MG, 100 lb/MG and 200 lb/MG (6mg/L, 12mg/L and 24 mg/L) Set different contact times at 0.5hrs, 3hrs, and 24 hrs Analyze filtered water for:
o Contaminants –- Benzene/TCE (GC/MS), MIB(GC/MS) and Microcystins (ELISA) o DOC o UV254
o Turbidity
River Spill Removal
• Spiked Benzene/TCE @10ppb
• ~60% removals can be achieved at a PAC dose of 50lb/MG (6 mg/L) and an HRT of 0.5hr for most PACs.
• Iodine# and PAC type did not seem to correlate with the removals.
Wood Lignite Bituminous
• PAC should be used for extracellular compounds.
• MIB is more challenging to treat than Benzene and TCE.
• Low removals were caused either by unsuitable PACs or insufficient doses
MIB
Intracellular
• Bituminous PACs outperformed wood and lignite PACs.
• A high PAC dose of 200lb/MG (24mg/L) was needed for a 60-75% removal with 3hr HRT.
• Iodine# seem to correlate with removals.
Wood BituminousLignite
MIB Removal Cont.
• A bituminous PAC with an iodine# of 1000 (WPH 1000) outperformed other PACs.
• A lignite/bituminous mixed PAC with smaller particle sizes (Carbpure 800RA) showed a higher removal than other 800s.
800RA: smaller sizes 800F: more mesopore
Wood Lignite/Bituminous Bituminous
• Spiked Microcystins @ 20 ppb (Collected on the River in 2019, freeze & thawed 3 times)
• A lignite/bituminous mixed PAC with a high iodine#(Carbpure 800) outperformed other wood and coal- based PACs.
• >60% removals can be achieved with a PAC dose of 100 lb/MG (12 mg/L).
• Iodine# seemed to indicate removal capacity for lignite and bituminous based PACs.
Algal Toxin Removal
• A lignite/bituminous mixed PAC with smaller sizes (Carbpure 800RA) outperformed other wood and coal PACs.
• The dose impact is less significant under well-mixed conditions.
Algal Toxin Removal Cont.
Question 2
What type of PACs do you have in your facilities? a. Wood based b. Lignite based c. Bituminous based d. Others e. No PACs
• PAC effectiveness changes as a function of contact time.
• <15% removal increase when time increased from 3hrs to 24hrs. The impact is more significant with contact times <30min.
• Contact time seems to be more critical at higher PAC doses.
Impact of Contact Time
Source: Valcarce, Gonzaga and Mazyck, 2017. Journal of AWWA 109:3
• Open jars with slow mixing mimicked reservoir condition, but MIB evaporated significantly, especially with long stirring hours (26-48% loss).
• Rapid-mixing in closed bottles increased MIB removals by 6-43% compared to open jars with slow- mixing.
Impact of Mixing Vs.
• TOC and UV254 are great indicators for MIB removal.
• TOC and UV254 are decent indicators for Microcystins removal.
• MIB and Microcystins are easier to remove than UV254 and TOC.
Surrogates for Contaminant
Removals
• Tested water TOC ranged 2-3 mg/L. TOC did not seem to impact MIB removal significantly in the tested range.
• Tested water average molecular weight is around 500 Dalton.
Impact of Background
Organic Matters
Flow scheme of the LC-OCD system LC-OCD chromatogram (typical) Source: Huber, Balz, Abert and Pronk .2011. Water Research 45(2), 879-885
PAC Types for Optimal Removals of Benzene/TCE, MIB, Toxins and NOM
Contaminants Formula Log Kow
Benzene &TCE 2.1 2.6
Bituminous
and mesopore (0.8-50nm)
(0.8-50nm)
Average Cost $/day
Wood UAC-H2O W ~$1300 45 670 330 $42,900 $21,500
Lignite Carbpure 500 ~$1020 50 410 $23,000
Carbpure 800, 800RA
WPH-1000 ~$1600 50 160 140 $14,100 $12,300
RMTP typical PAC dose range is 50 - 200 lb/MG in reservoirs, so a PAC with the highest removal and relatively low cost is recommended.
Summary and Recommendations
• PAC adsorption is effective for the removal of tested petrochemicals, extracellular T&O compounds, and cyanotoxins.
• A micropore PAC with high iodine# (WPH 1000) is recommended for MIB with a small molecular size.
• A mesopore PAC with high iodine# (Carbpure 800 RA) is recommended for Microcystins with big molecular sizes.
• Choose the best location for PAC application to improve efficiency and save costs, i.e., longer contact time, better mixing, low DOC and turbidity.
• DOC and UV254 could be used as indicators for MIB/ Microcystins removals if the sizes of the background NOM are similar to MIB/ Microcystins.
• Understand the performance limits of your PAC system
• Select PACs based on costs and performance
• Competitively bid PACs to reduce cost
• Monitor source water and reservoirs for contaminants
Future Research
• Evaluate temperature impact on PAC adsorption
• Test other alternatives for algae, T&O compounds, and algal toxin control
Acknowledgements
GCWW WQT Organics lab staff: o Niranjan Selar o Alex Mendlein o Mardochee Isme o Josh Crandall
GCWW WQT lab techs and co-ops o Aimee Poulin o Ali Richardson
Ying Hong, Ph.D., P.E. Water Quality & Treatment
Greater Cincinnati Water Works (513) 624-5664
Ohio River Spills
Slide Number 3
Slide Number 4
Question 1
Tested PACs
Experimental Goals and Plan
Slide Number 17
Slide Number 18
Slide Number 19
Slide Number 20
PAC Types for Optimal Removals of Benzene/TCE, MIB, Toxins and NOM
PAC Costs