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  • Steve Booton

Apparently, Poo is the New Fertilizer

Updated: Apr 4

Yes, it’s in the news again. Poo aka Biosolids is once more being touted as the replacement for chemical fertilizers. Growing up, I remember the smell that would waft away in the breeze for days as farmers used animal effluent to cover their fields with the goal of adding much-needed nutrients back into the soil. Scary thought…

I felt compelled to put my thoughts into words, once I read an article that wrote about the use of human effluent as an alternative - “A groundbreaking trial that started 20 years ago fertilising Queensland cotton farms with treated human sewage has become so popular more than 100 farmers are now on the waiting list”. Read the full article here.

You may think “it’s only cotton” and I cannot eat that, well think again. If that waiting list gets hold of commercially sold poo, then expect your everyday vegetables to be fed what your body or industry extinguished in the first place. Whilst the article and the feedback provided by farmers on the performance using such effluent was encouraging, what it does not mention are the real facts.

Millions of kilograms of human effluent pass through and receive treatment in wastewater facilities every day. The discharged water, after cleaning, leaves behind toxic sludge that wastewater treatment plants must dispose of. This biosolid sludge is expensive to dispose of because it must go to a landfill, but the waste management industry is increasingly using a money-making alternative – repackaging the sludge as fertilizer and injecting it into the nation’s food chain.

As mentioned in the article, sludge holds nitrogen, phosphorus and other nutrients that help crops grow, so the waste management industry lightly treats it and sells it cheaply to farmers who view it as a cost-saving product and an alternative to traditional chemical controls. What it does not say is the presence of other contaminants that are near on impossible to remove under current processes.

The excrement from which sludge derives has mixed with any number of manufactured chemicals that industry discharges from pipes or otherwise dump into the sewer system. By the time the mix lands in treatment plants, it can be teeming with pharmaceuticals, hormones, pathogens, bacteria, viruses, protozoa, and parasitic worms, as well as heavy metals like lead, cadmium, arsenic, or mercury. It often includes PCBs, PFAS, dioxins, BPAs and dozens of other harmful substances ranging from flame retardants to hospital waste.

The waste management industry treats sludge in several ways – air drying, pasteurization and composting are among common methods before labelling it as fertilizer. Lime is added to raise the pH level to reduce odour, and about 95% of pathogens, viruses and other organisms are killed in the process.

However, the thousands of chemicals known to be in biosolids, or tens of thousands of synthetic chemicals that remain behind and which are not tested or cannot be removed. Sewage sludge is behind a widening PFAS crisis. PFAS, or “forever chemicals”, are linked to a range of serious health problems like cancer, thyroid disorders, immune disorders, and low birth weight. The chemicals are a product used to make non-stick or water-resistant products and are found in everything from raincoats to dental floss to food packaging.

In the USA

In biosolid testing that the EPA has conducted, it has identified more than 350 pollutants. That includes 61 it classifies “as acutely hazardous, hazardous or priority pollutants”, but the law requires only nine of those be removed. Moreover, the EPA and wastewater treatment plants don’t test for or otherwise analyse most of the 80,000 manmade chemicals.

In a scathing 2018 report, the EPA office of inspector general noted the agency couldn’t properly regulate biosolids, even if it sincerely tried, because “it lacked the data or risk assessment tools needed to make a determination on the safety of 352 pollutants found in biosolids”.

Though regulators and industry don’t know what’s in biosolids, there’s strong evidence that it can be dangerous.

A University of North Carolina study found 75% of people living near farms that spread biosolids experienced health issues like burning eyes, nausea, vomiting, boils and rashes, while others have contracted MRSA, a penicillin-resistant “superbug”.

In South Carolina, sludge containing high levels of carcinogenic PCBs was spread on cropland, and in Georgia sludge killed cows. Biosolids are also thought to be partly responsible for toxic algae blooms in the Great Lakes and Florida, and biosolid treatment centres regularly pollute the air around them. Source The Guardian

In Australia

Treatment options for PFAS-impacted wastes are extremely limited. This is due to the chemical characteristics of PFAS and because the chemicals are relatively new contaminants of concern.

In general, thermal treatment of PFAS via incineration seems to be the best treatment possible. The EPA is aware of several facilities that have this capability.

If a waste disposal contractor tells you that it can treat PFAS waste, EPA recommends you check that the company can prove its ability to effectively destroy or permanently capture PFAS.

In England

The Environment Agency says PFAS is “ubiquitous in the environment”, particularly in its waters, making it unlikely that drinking water sources have escaped contamination. But unlike countries such as the US, where a nationwide testing scheme is underway, the UK government has so far only made plans to make plans to understand the levels of water pollution.

The Department for Environment, Food and Rural Affairs (Defra) says it takes “the risks posed by PFAS chemicals very seriously, which is why we’re working at pace with regulators to better assess their presence in our natural environment and their sources.”

In summary

Worryingly, land application of biosolids is gaining popularity and is seen as beneficial in terms of resource recovery and soil improvement, however, there are greater concerns regarding human health hazards and the environment. Regardless of how biosolids are treated, it has been shown that pathogen reactivation and regrowth in land-applied biosolids is one of the growing risks.

Pathogen reactivation/regrowth may be the source of contamination to the crops and animals, which eventually affects humans through the food chain, or another issue is the generation of odour and aerosols.

These methods involve the spreading, spraying, injection, or incorporation of biosolids onto or below land surface. As the biosolids are rich in organic matter such as proteins, amino acids and other nutrients, the decomposition of these compounds emits a very noticeable noxious odour.

The aerosolization of biosolids is also an inherent problem, especially during application and under windy conditions. Aerosols from biosolids can also contain pathogens, biotoxins, as well as harmful chemical compounds. It has also been claimed that more robust faecal indicators such as Clostridia and coliphages, which are more resistant to thermal treatment, are prevalent in aerosols.

For biosolids to be managed and produced in a sustainable manner, further research and efforts are needed to achieve higher quality, improved nutrient recovery, and a higher degree of public understanding and acceptance.

The lack of knowledge on heavy metal contamination other emerging organic wastewater contaminants including steroids, pharmaceuticals, disinfectants, pesticides, polyaromatic hydrocarbons (PAHs), metabolites of soaps and detergents, hormones, etc. arising from biosolids, needs immediate stringent regulations to be formulated.

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