MacroPlastics in Toxic Sewage Sludge

MacroPlastics

For purposes of this writing, MacroPlastics are plastic debris in Toxic Sewage Sludge or other wastes larger than 1 mm by any dimension, whereas MicroPlastics are less than 1 mm. Size will vary over time as a result of decomposition in the environment. MicroPlastics are not removed by screening systems, and therefore contaminate Toxic Sewage Sludge and other waste products. Soils, waterways and marine environments are impacted most by unmanaged plastic wastes in Toxic Sewage Sludge and Solid Wastes. MacroPlastics and MicroPlastics form a growing portion of common solid waste material. Most is toxic waste (http://www.rsc.org/images/Leslie_tcm18-239910.PDF).

 

More than people are negatively impacted or adversely affected by exposure to the toxics in Toxic Sewage Sludge. In addition to a few select forest fungi (Mycena spp. And other mushrooms) and plants (Blackberries) that we have observed, a few animals also seem to suffer no ill effects from life in a toxic waste pool. I have watched certain toads and frogs progress from egg to adult stages, and appear to thrive in toxic sludge leachates and runoff. Nature can be amazing, but then what would a serious pathology investigation show?

Plastic Pollution

 https://en.wikipedia.org/wiki/Plastic_pollution

Plastic Pollution is the accumulation of plastics in the environment that adversely affect wildlife, wildlife habitat and humans. Plastics are pollutants, and are correlated with plastics being inexpensive and durable, which lends to high levels of use. Plastics degrade slowly. Plastic pollution can unfavorably affect lands, waterways and oceans. Living organisms can be affected by direct ingestion or exposure to chemicals within plastics that alter biological functions, such as hormone disruption.

 

What is the fate of the remaining hormones (generally only about 80% used) in the implantable contraceptive devices that find their way into forests and on farms? Does it prevent Slugs from reproducing, or better yet, perhaps the Sludgers?

Plastic Debris

There are three major forms of plastic debris that contribute to plastic pollution: MicroPlastics, MegaPlastics and MacroPlastics. Plastic debris is categorized as either primary or secondary. Primary plastics are in their original form (e.g., bottle caps, cigarette butts and microbeads). Secondary plastics result from degradation of primary plastics. The definitions in the literature vary by Author.

MicroDebris

(https://marinedebris.noaa.gov/sites/default/files/MicroplasticsOnePager_0.pdf)

MicroDebris includes plastic pieces between 2 µm and 5 mm in size. Plastic debris that begins as meso- or macrodebris can become microdebris through degradation into smaller pieces. Plastic debris is categorized as MacroDebris when it is larger than 20 mm (Note the differences in criteria for defining MacroPlastics vs MacroDebris).

 

Typical veggie label (Produce Sticker) in sewage sludge - by the millions. Some are compostible or decomposable; some are edible; most are simply plastic.

Decomposition of Plastics

Plastics themselves contribute to approximately 10% of discarded waste. Many kinds of plastics exist, depending on their precursors and the method for their polymerization. Depending on their chemical composition, plastics and resins have varying properties related to contaminant absorption and adsorption. Recent studies show that plastics decompose faster than was once thought, because of exposure to sun, rain and other environmental conditions, resulting in the release of toxic chemicals. It is estimated that global production of plastics is approximately 225 mt/yr. They are found to transport Persistent Organic Pollutants (POPs).

 

Sift a pail of fresh sewage sludge from a typical local wastewater treatment plant, and you get a pile of MacroPlastics - lots of it. It decomposes into what???

MicroPlastics

 https://en.wikipedia.org/wiki/Microplastics

MicroPlastics are small plastic particles, generally smaller than 1 mm (0.039 in) down to the micrometer range. They originate from cosmetics, clothing and industrial processes. There are two classifications of MicroPlastics: i) Primary Microplastics, which are manufactured, and are a direct result of human material and product use; and, ii) Secondary Microplastics, which are microscopic plastic fragments derived from the breakdown of larger plastic debris. Both types are recognized to persist in the environment at high levels, particularly in aquatic and marine ecosystems. Plastics do not degrade for years, and can be ingested and accumulate in the tissues of many organisms.

 

These are MacroPlastics that decompose or degrad by various processes into MicroPlastics. Interestingly, the sifting process also reveals fly larvae.

Primary MicroPlastics

These are particles of plastics that are purposefully manufactured to be microscopic. They are usually used in facial cleansers and cosmetics, or in air blasting technology. They are used in medicine as vectors for drugs. Microplastic "scrubbers" are used in exfoliating hand cleansers and facial scrubs, replacing traditional natural ingredients.

 

Whoops! Dropped my toothbrush down the toilet again.

Secondary MicroPlastics

These are described as microscopic plastic fragments derived from the breakdown of larger plastic debris, both at sea and on land. Over time, a culmination of physical, biological and chemical processes can reduce the structural integrity of plastic debris, resulting in fragmentation. MicroPlastics degrade to smaller size, although the smallest microparticle reportedly detected is 1.6 micrometres (6.3×10−5 in) in diameter.

 

The curious combinations of plastics, hair, fibers, metal and bone fragments, microbes, including infectious agents, toxic chemicals, and, oh yes, a few plant nutrients.

Other Sources of MicroPlastics

MicroPlastics are often a by-product or dust emission product from wear and tear. Examples are dusts from synthetic textiles, ropes, paint and wastewater treatment. Estimates of emissions of MicroPlastics to the environment in Denmark are between 5,500 and 14,000 tonnes (6,100 and 15,400 tons) per year. Secondary MicroPlastics (e.g. from tires or footwear) are more important than primary MicroPlastics. The first International Workshop on the Occurrence, Effects and Fate of Microplastic Marine Debris was at the University of Washington, Tacoma, WA, September 9–11, 2008: “Microplastics pose problems in the marine environment.” Plastic particles may concentrate and transport synthetic organic compounds, including POPs, commonly present in the environment, on their surface through adsorption. Also, additives to plastics during manufacture may leach out upon ingestion, potentially causing serious harm to the organism. Endocrine disruption by plastic additives may affect the reproductive health of humans and wildlife alike.

 

Hair? What hair? Whose hair? In the forest? On the farm? On my food? No way. Way!

 http://www2.mst.dk/Udgiv/publications/2015/10/978-87-93352-80-3.pdf

MicroPlastics - Occurrence, effects and sources of releases to the environment in Denmark

Environmental project No. 1793, 2015. Carsten Lassen, et al. The Danish EPA, Strandgade 29 1401 Copenhagen K, www.eng.mst.dk, 2015, ISBN no. 978-87-93352-80-3.

An increasing body of scientific studies demonstrates that small plastic particles designated as “microplastics” are widespread in the environment, accumulate in organisms and may have harmful effects on organisms and ecosystems, in particular in the marine environment.

The microplastics originate from various sources:

·         Primary microplastics intentionally used in products and processes

·         Fragmentation of larger plastic litter in the environment

·         Releases from plastic items and coatings of products still in use

·         The significance of the different sources as regards the levels of microplastics found in the environment is still poorly understood

·         Plastics that are released into the environment can remain in the environment for hundreds of years before they finally decompose

·         Global consumption of plastics is increasing, and global emissions are likewise expected to increase, unless action is taken against emissions

·         Plastics ending up in the sea may be transported over long distances; even the most remote places on the planet are affected by plastics pollution

·         In the environment, plastic pieces degrade into smaller pieces, meaning macroscale plastics degrade to microscale plastics, which further fragment into nanoscale plastics

·         Microplastics are detected in organisms at all levels of the marine food chain

·         Research shows that microplastics may have effects on organisms in the environment, but our knowledge of the magnitude of these effects is limited

·         We have virtually no knowledge on the possible particle effects of nanoscale plastic particles due to their size

·         People can be exposed to microplastics via food

Microplastics in Sewage Sludge: Toxics Upon Toxics

Richard C Honour (July 30, 2016)

Sewage sludge, the solids separated from raw sewage in a Wastewater Treatment Plant (WWTP), collects and holds the physical materials, chemical wastes and microbial matter from all sources that contribute to sewage inflows. WWTPs degrade much of the organic matter in raw sewage by microbial digestion, but screening, settling, filtration and dewatering assure that most of the residual physical materials and the poorly-degraded Toxics (poisonous substances) partition to the solid phase, i.e., to the sewage sludge that is destined for land disposal in forests or on farms and rangelands. But what fate awaits the toxics?

Components of sewage sludge that are not degraded in a WWTP, including plastics, are land-disposed, and thereafter degrade as a function of their chemistry and the environment to release toxics by many routes. Plastics in sewage sludge originate as manufactured products in commerce, including as pharmaceutical or personal care products, product wrappers, produce labels, fibers from fabrics, and as fragments of larger plastics. In any case, plastics are: Carriers of toxics; and, Sources of their own toxics as they degrade in the environment.

Microplastics are considered to be about 1 mm or less in size, but for plastics encountered in sewage sludge, we consider microplastics to be as large as 10 mm. Last year, King County, WA, modified the mesh size of the screens in their WWTPs from one-half inch to three-eighths inch (about 10 mm) in an effort of reduce the size and load of ‘Physical Inerts’ in their sewage sludge product.

The forms and chemistries of microplastics in sewage sludge are beyond what should be disposed in forests or on farms and rangelands, because the chemistry and toxicity of the degrading microplastics, and from the adsorbed toxics, remain mostly unknown. Similarly, the distribution, fate and toxic effects of these chemicals in soil and water, and their bioaccumulation in biota, also remain unknown. The most likely outcome is Environmental Toxicity (harmful effects of toxics on living organisms).

Sewage sludges from WWTPs hold examples of most classes of toxic pollutants, including Persistent Organic Pollutants (POPs), Chemicals of Emerging Concern, and Persistent Bioaccumulative Toxics, with hundreds of synthetic members of these groups known to accumulate in sludge.

Common plastics, such as Low-Density Polyethylene, form the basis of a vast plastics industry, including for use in Pharmaceutical and Personal Care Products, and they are natural accumulators of toxic chemicals, including Brominated Flame Retardants, such as the Polybrominated Diphenyl Ethers, as well as Nonylphenols, Dioxins, Furans and Polychlorinated Biphenyls (the infamous PCBs). These are some of the highest priority toxic chemicals encountered in any domestic, medical, industrial or agricultural wastewater stream. The presence of these plastics in raw sewage, and then in the wastewater treatment process, assures their bonding with priority toxic chemicals in wastewater, and their ultimate partitioning and accumulation in the resulting sewage sludge product.

Land disposal of this toxic chemical debris assures broad dispersal of plastics into the surrounding environment, with the microplastic-borne toxics being released thereafter, as the parent materials degrade naturally in the presence of ultraviolet light, and by oxidation and microbial degradation.

Analysis of sewage sludge samples from a King County, WA, WWTP, as collected from a Snoqualmie Forest land disposal site, revealed a menu of toxic flame retardants that surpassed what was expected. The forest-disposed, sewage sludge-borne toxic flame retardants included:

It is notable that Pentabromodiphenyl ether (BDE-85) was eliminated from production under the Stockholm Convention, a treaty to phase-out POPs. It is found at elevated concentrations in air, water, soil, food, sediment, sewage sludge and dust; it enters the body by ingestion or inhalation; it is stored in body fat, and it is retained in the body for years. PDE-47 and PDE-99 accumulate in terrestrial carnivores and humans at rates higher than any other industrial chemical. Tris (1,3-dichloroisopropyl) phosphate (TDCPP) is a chlorinated organophosphate, various forms of which are used as flame retardants, pesticides, plasticizers and nerve gases.

More than 70% of toxic chemicals detected in sewage sludge are also detected in humans. They concentrate in sewage sludge, are persistent in the environment, bioaccumulate in fatty tissues, have degradation products with elevated toxicity, and are synthetic, rarely occurring as single compounds.

Until these toxic chemicals can be eliminated from raw sewage and other wastewater streams, it will be important to expand testing of all sewage sludges and wastewater effluents to assure that the risk and threat may be determined and the public placed on alert.

Placing the burden of toxics elimination on commerce and industry as a source-control strategy may be the only effective action until an enhanced wastewater treatment process can be integrated into the WWTP system to protect human and environmental health. A thermal degradation process, for example, such as Plasma Arc Gasification (PAG), can reduce organic chemicals and plastic wastes, including microplastics, to syngas that may be used as a source of heat for energy, with minimal residual ash that is safer and more easily disposed.

PAG of sewage sludge involves super-heating the sludge in an oxygen-starved environment to preclude combustion, with the intent to offer cleaner emissions, substantial energy production and the near elimination of land disposed ash. While shown to work well in model projects, none of the emerging gasification technologies has yet been reduced to practice on an industrial or municipal scale in the US.

Richard C. Honour is Executive Director of The Precautionary Group, Kenmore, WA, and Vice President and Director of the North American Alliance for Clean Land, Chapel Hill, NC.

 https://www.dropbox.com/s/e500m9ha2woxa2f/Plastic%20debris%20in%20oceans%20a%20growing%20hazard%20as%20toxins%20climb%20the%20food%20chain.pdf?dl=0