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SOURCES OF MICROPLASTICS TO THE GREAT LAKES: WASTEWATER TREATMENT PLANTS
By: Mala C. Hettiarachchi, PhD, PE
Presentation to:
January 2019
SHOUT-OUT Thankful for ERG’s support on microplastic research and outreach.
ERG pledged to provide about $100,000 in-kind support for the NOAA grant application submitted in December 2018 to conduct microplastic characterization and fate and transport research.
Appreciate the support provided by the co-author, Matthew J. Germane, PE
Thankful for Monika Hentze and Mathias Bath, PhD of Germany for letting me use their WWTP information for this presentation.
Proud of the ERG ownership and employees who are committed to minimize plastic pollution via personal actions.
We are a small, nimble, very experienced company with more than 25 employees at three offices in Michigan (Detroit, Wixom, Muskegon).
PRESENTATION CONTENT
Plastic pollution
Outreach - Plastic waste minimization
Background of Microplastics
WWTPs as a source of microplastics
Sustainable WWTP – Example
Microplastic Removal at WWTPs
PLASTIC POLLUTION
AT A GLANCE Plastic is strong, flexible and durable
making it extremely useful.
Plastic is persistent in the environment. For example, a plastic bottle can last for 450 years in the marine environment, slowly fragmenting into microplastics.
Removal of the microscopic plastic pieces in our oceans is an impossible task.
Studies show that at least 8 million tons of plastic waste enter the oceans every year. Source: University of South Carolina
Remnants of a bird that died with the plastic
in its gut.
Approximately 100,000 marine mammals and turtles and 1 million sea birds are killed by marine plastic pollution annually.
PLASTIC POLLUTION IN THE GREAT LAKES
Rochester Institute of Technology estimated that nearly 22 million pounds of plastics enter the Great Lakes every year.
Source: Driedger et. al. (2015)
OUR CONTRIBUTION TO PLASTIC POLLUTION
Americans represent 5% of the world’s population and generate 30% of the world’s garbage.
In a lifetime the average American will personally throw away 600 times his/her adult bodyweight of trash – mostly plastic waste.
Americans use approximately 2,500,000 plastic bottles every hour and only less than 15% are recycled.
In the USA, 500 million plastic straws are used every day.
How we can help? Stop using more plastic and spread the word.
OUTREACH –PLASTIC WASTE MINIMIZATION
PREVENTION OF MARINE PLASTIC POLLUTION
Source control is one of the best solutions to this global problem. This can be achieved by:
Regulations
Outreach – via raising public awareness on plastic pollution
Promoting behavioral changes
Source control using technology
New recycling methods
Innovative uses of plastic waste
CURRENT REGULATIONS: MACRO-PLASTICS Rwanda: Banned single-use plastic bags in 2008 and has a zero tolerance policy toward plastic bags.
Europe: The European Parliament voted for a complete ban on a range of single-use plastics across the union in October 2018. The ban will go into effect across Europe by 2021.
Kenya: As of August 2017, anyone using, producing, or selling a plastic bag faces up to four years in jail, or a $38,000 fine.
Morocco: Banned the production, import, sale, and distribution of all plastic bags in July, 2016 (Prior to the ban, Morocco was the second largest plastic bag consumer in the world after the USA)
China: On December 31st, 2017, China banned the plastic waste that was imported from industrial countries like the USA for recycling / disposal. This ban might leave 111 million metric tons of plastic trash with nowhere to go. China has imported about 45% of the world plastic waste since 1992 for recycling.
City of Montreal: Banned single-use plastic bags in 2018; Seattle: Banned plastic straws and single-use plastic utensils in July 2018; New Delhi (a city of 20 million): Banned all forms of single-use plastic in 2017; California: Banned full-service restaurants from providing plastic straws unless requested in 2019.
Australia: Banned free, lightweight plastic bags in 2018.
Reduce, reuse, and recycle to minimize plastic pollution
• Segregation is essential for recycling to be effective. Contaminated waste streams will end up in landfills or our oceans.
• Remember, recycling comes after prevention, minimization and reuse in the waste management hierarchy.
SOLUTIONS How many times can plastic be recycled?
Most Recyclable Plastics: 1-2 timesThe size of the carbon chain gets reduced when
recycled due to heat and mechanical stress.
Plastic is recycled to make fibers (e.g., for clothing).
Most of the time, plastic products created with
recycled plastics cannot be recycled.
HDPE: Maybe recycled 4-7 times due to their long
carbon chain.
Glass and Metal including aluminum: Unlimited
number of times or infinite
Paper: 5-7 times. With each recycling process, the
fibers become shorter, coarser and stiffer. Final uses are egg cartons or newspapers -- biodegradable.
TYPES OF PLASTIC
#1: PET (Polyethylene Terephthalates) - single
use; repeated use may leach carcinogens;
recyclable to make fiber {e.g. Water bottles}
#2: HDPE (High-Density Polyethylene) – one of
the safest forms of plastic; reusable and
recyclable {e.g. shampoo bottles}
#3: PVC (Polyvinyl Chloride) - contains many
leachable toxins; not recyclable {e.g. food foil}
#4: LDPE (Low-Density Polyethylene) - less toxic
than other plastics; reusable; not easy to
recycle {e.g. shopping bags}
#5: PP (Polypropylene) – recyclable and
reusable {e.g. toys, furniture}
#6: PS (Polystyrene) – May leach styrene (a
carcinogen) when heated; not easy to recycle
{e.g. toys, vending cups}
#7: Other – contains BPA; not usually recycled
{e.g. nylon}
#7 PLA: compostable plastics
#7 PC: ‘non-leaching’ but trace amounts of BPA
can leach when heated or used for hot liquids
THINGS YOU CAN DO
Say no to straws and plastic water bottles
Use reusable/washable cloth grocery bags
Use cotton produce bags
Buy milk/juice in glass bottles
Buy products stored in glass, metal or paper/cardboard containers
Use stainless steel washing machine lint traps to capture plastic fiber
Minimize, reuse, and recycle
We can help reduce plastic pollution right now with our personal choices and actions
BACKGROUND OF MICROPLASTICS
MICROPLASTICS: AN EMERGING CONCERN Microplastics are pieces of plastic smaller
than 5 millimeters.
PRIMARY microplastics are purposefully manufactured to be of microscopic size.
SECONDARY microplastics are derived from the fragmentation of macroplastic items.
Found virtually everywhere: water, sediments, soil, and air.
Microplastics with size ≤ 20 μm can penetrate into organs.
Fate and transport of very small microplastics (e.g., nano particles) is yet to be discovered.
CURRENT REGULATIONS: MICROBEADSSeveral counties have banned (or are proposing banning) the sale, manufacture, and import of rinse-off products containing microbeads.
USA (2015 Microbead-Free Waters Act); Canada; multiple European nations; Taiwan, UK, New Zealand, Australia, India.
Note: While the composition of microplastics varied spatially and temporally, it is dominated by fibers, fragments, and flakes, as opposed to beads and pellets.
Source: http://www.waterkeeper.ca
MICROPLASTICS IN THE FOOD CHAIN
Microplastic ingestion causes physical harm and reproductive complications in marine / freshwater life
New research showed that microplastics are getting into mosquitoes. This means contaminating the animals in the air like bats, dragonflies, and crickets and an unlikely food chain
A Damselfish larva that has ingested tiny
plastic particles
SORPTION BEHAVIOR
Microplastics can act as vectors of additives incorporated during manufacture and toxic pollutants sorbed from the surrounding media to biota.
The sorption behavior of some PFAS to the types of microplastics (polyethylene, polystyrene, and polyvinylchloride) are evident (Wang et.al., 2015).
The molecular composition and structure of microplastics play important roles in the sorption processes of toxic pollutants.
Photo source: Google
MICROPLASTICS IN HUMANS
Microplastics in human stool, in the size range from 50 to 500 µm, have been identified by the Medical University of Vienna and the Austrian Federal Environment Agency in 2018, in all eight participants of their pilot study.
Microplastics have been detected in bottled water and tap water.
The World Health Organization (WHO) announced in March 2018 that it is launching a review of the potential risks of plastic particles in drinking water.
The complete impact on human health is yet to be discovered.
WASTEWATER TREATMENT PLANTS AS A SOURCE OF MICROPLASTICS
SOURCES OF MICROPLASTICS
Atmospheric
Deposition
AND
Many others
Combined Sewer Overflow
Storm Sewers
WWTPs
Runoff
Photo source: Google
SOURCES TO THE GREAT LAKES –WASTEWATER EFFLUENT
There are several WWTPs, including
Detroit WWTP, one of the largest
facilities in the USA with the dry
weather capacity exceeding 650
million gallons per day, that
discharge wastewater to the Great
Lakes.
Unfortunately, these facilities are
not designed to remove small
microplastics from the effluent.
SOURCES TO THE GREAT LAKES – BIOSOLID LAND APPLICATION
Land application of sewage sludge or biosolids on agricultural land is a commonly used method.
Between 110,000 and 730,000 tons of microplastics are transferred every year to agricultural soils via biosolid land application in Europe and North America (Norwegian Institute for Water Research).
A large portion of the microplastics re-enter the aquatic environment via agricultural runoff.
Effect of microplastics on soil organisms, and their impact on farm productivity and food safety is unknown.
Note: In addition to microplastics, other micropollutants such as PFAS are presence in biosolids. The regulatory limit for PFOA and PFOS for sewage sludge for land application in Germany is 0.1 mg/kg of dry sludge.
Photo source: Google
SUSTAINABLE WASTEWATER TREATMENT PLANT - EXAMPLE
Anaerobic digestors and waste-to-energy processes are typical in German WWTPs.
Many European WWTPs employ tertiary wastewater treatment techniques to remove micropollutants providing an indirect opportunity to remove very small microplastics.
Per the German sewage sludge ordinance which came into effect in October 2017, land application of traditional biosolids is allowed only for WWTPs less than 50,000 p.e.
DRESDEN WWTP
PHOSPHORUS RECOVERY
Phosphorus recovery: Per Germany’s October 2017 sewage sludge ordinance, WWTPs larger than 50,000 p.e. must recover the phosphorus if the sludge contains more than 2% phosphorus /DS (dry solids).
Due to the new phosphorous recovery requirement, most German WWTPs will use mono-incinerators (sewage sludge incinerators) to recover phosphorous from ash.
These new regulations help achieve complete destruction of micropollutants including microplastics in sludge.
ASH DEC process: Thermochemical treatment -produces renewable phosphate and separates heavy metals
Energy mix – Dresden WWTP (wind; solar; CHP {green}; grid {blue})
RENEWABLE ENERGY
Approx. 80% of the Dresden WWTP’s energy needs was produced onsite in 2016
MICROPLASTIC REMOVAL AT WWTP
REMOVAL ALTERNATIVES
Method 1: Source reduction (Examples: public outreach, simple techniques such as fiber traps at washing machines, regulations, etc.)
Method 2: Entrainment of microplastics in sewage sludge during settlement processes and filter out micro and nano particles from the effluent water prior to discharge.
Method 3: Treat the biosolids that contain various micropollutants, including microplastics.
Method 4: Other new methods (e.g., Microbial degradation of microplastics)
SOURCE REDUCTION (PUBLIC OUTREACH)
Most people like to help but they need guidance and knowledge.
Example:
The WWTP in Dresden, Germany has reduced about 90% of undesirable garbage flushed down the toilet since 2015 via a 4P public campaign.
The campaign was adapted by some WWTPs in Germany, Austria, Poland and Czech Republic.
ENTRAINMENT OF MICROPLASTICS IN SLUDGE
Coagulation/flocculation / precipitation
Micro Screening (e.g., Drum filters and disc filters)
Filter openings from 10 µm,
Can be an alternative to primary settlement tanks especially for small WWTP.
Can be a primary or tertiary treatment.
Photo source: Google
ENTRAINMENT OF MICROPLASTICS IN SLUDGE
Activated Sludge Treatment - Bio flocculation helps settle microplastics.
Rapid Sand Filters – can a tertiary treatment option.
Photo source: Google
ENTRAINMENT OF MICROPLASTICS IN SLUDGE
Dissolved Air Floatation
Membrane Filtration (tertiary treatment)
Photo source: Google
TREATMENT OF BIOSOLIDS
Per the German sewage sludge ordinance which came into effect in October 2017,
land application of traditional biosolids is allowed only for WWTPs less than 50,000 p.e.
Photo source: Google
TREATMENT OF BIOSOLIDS - INCINERATION
Photo source: Google
TREATMENT OF BIOSOLIDS - GASIFICATION
A thermochemical process which converts organic materials into
gaseous components.
Photo source: Google
TREATMENT OF BIOSOLIDS - PYROLYSISThermal decomposition of organic materials at elevated temperatures in
the absence of oxygen.
Photo source: Google
TREATMENT OF BIOSOLIDS –ANEROBIC DIGESTION
Anaerobic digestion seems to facilitate the breakdown of microplastics
Photo source: Google
OTHER OPTIONS
Biodegradation - Some microorganisms can
degrade plastic polymers.
Hybrid silica gels – Recent study successfully
utilized silica gel to remove microplastics and
pharmaceuticals from water.
Photocatalytic oxidation.Photo source: Google
KNOWLEDGE GAPS Further research is needed to reduce microplastic pollution in marine environments:
Innovative sampling methods to identify/quantify microplastics (micro and nano particles) in soil/sediment and water.
Mechanisms of microplastic fragmentation.
Identification, characterization and quantification of significant microplastic sources per size, type, and shape.
Microplastic removal technologies.
Microplastic mass balance at WWTPs.
Fate and transport of microplastics in biosolids.
New recycling methods.
CONCLUSIONS
Microplastic pollution is very real and potentially very damaging.
We can help reduce plastic pollution right now with our personal choices and actions.
Source control is one of the best solutions to this global problem.
Process upgrades at WWTPs can provide removal of emerging pollutants as an indirect benefit.
Obtaining funding for microplastic work is challenging due to the lack of regulations.
