Biosolids Quality - Contaminant Surveillance



This was the message my laptop greeted me with on Friday morning. My  computer repairman later confirmed my fear.  All was lost, at least since my last backup. But that meant I needed to “reboot” my commentary, completed the night before, and start again. Hence, my tardy Biosolids in the News from last week.

I was asking this question in my commentary: why, even with a long history of aggressive regulation of industrial discharges to the sewers in our older East Coast cities, are metal concentrations in the biosolids still considerably above state-wide norms?

I posed this question to myself because I was preparing for my presentation at the NJWEA 100th Annual Conference biosolids symposium. It is this Thursday, May 14th, at Bally’s in Atlantic City.  I will be telling the story of industrial pretreatment from the viewpoint of senior biosolids managers who have been around for at least a generation. The goal back in the late 1970s was to create a material we could assure was safe from pollutant discharges that would interfere with recycling to land.

Now, a generation later, that is still our goal in the wastewater profession. What is more, I argue,  we all need to re-commit (or, in light of my computer disaster “reboot”) to continual improvement in the quality of our biosolids.

Specifically, for this current inquiry, why are lead, copper and zinc levels in Philadelphia’s biosolids still higher than national and state norms, despite 30 years of aggressive industrial pretreatment?  Philadelphia’s current estimation is that less than 2% of metal loadings to biosolids are from these “SIUs.” So our metals are from other sources, not well defined; so what are they?

I had several hypotheses: combined sewers in the old cities capture road dirt and eroded urban soils; old and contaminated roofing material leaches during rain through downspouts to the sewers; and, corroded “premises plumbing” and “lead service lines” release metals from the household water pipes into drains.

I took to Google Scholar for some scientific “truth telling.”  Several  papers allowed  me to make some coarse estimates of loading parameters from road surfaces and roofs. These are:  Sources and transport pathways of common heavy metals to urban road surfaces andStorm water runoff concentration matrix for urban areas.  I also looked for information on the release of metals from corroding water systems.  Impact of water treatment on the contribution of faucets to dissolved and particulate lead release at the tap.  Bottom line, a rough estimate would allocate 10% to 20% of the copper, lead and zinc in urban biosolids to road dirt and a similar proportion to old plumbing. But, this is still not a complete explanation, and I remain curious, and I hope you are, too.

Two decades ago, we solved our heavy metals issues in biosolids in the US.  Philadelphia’s biosolids, along with almost all biosolids in the nation, remains comfortably better than the Table 3 Pollutant Concentrations of Part 503.  But mostly, we accomplished this by exporting the polluting industrial activity to undeveloped countries on the other side of the world.  In reviewing the early descriptions of our program in Philadelphia, it was no secret that a changing global economy was a major factor in the closing of metal plating companies in the city. Even back in the 1990s we conjectured that reduced metals discharges in Philadelphia companies corresponded to increased discharges in Asia.

So I searched Google Scholar for what is known about metals in Asia. I confirmed that Industrial pretreatment is a success story that cannot yet be told proudly in Asian cities.  With the intense media coverage of severe health alerts from air pollution in China, we cannot be surprised that exposure risks from other media, such as biosolids and water, would not also be higher than in the United States.  Robust research is underway, and a journal article by a Chinese scientist in Beijing expressed the point of view that heavy metals from industrial discharges in Beijing’s biosolids were too high to permit land application.  PCDD/F, PAH and heavy metals in the sewage sludge from six wastewater treatment plants in Beijing, China.

We ought to take little solace, then, in the good quality of biosolids here. The high environmental risks from persistent pollutants and heavy metal contaminants abroad has a global dimension. In the year 1975, when Philadelphia was signing up at EPA’s urging to undertake heavy metals discharge control, the world population was 4.1 billion. Today the world is at 7.2 billion and on its way to 9 billion by 2050.  The global per capita extraction and production activities have also increased during these past four decades,  meaning that global discharges of  metals discharges have more than doubled since 1975. We may be complacent and short sighted in thinking our job with improving biosolids quality is done, just because industrial pretreatment has succeeded in having our nation’s biosolids meet 503 standards.  One issue is that we are not so separated here in the U.S. from Asia that we can wholly ignore global contamination. Putting aside the enormous ethical issue of global social justice, we have, for one example, global air currents carrying pollutant dusts across the ocean: Climatology of long-range transported Asian dust along the West Coast of the United States.

We also would be short-sighted not to realize that new analytical instruments open up a whole new opportunity for us to reduce pollutants in biosolids.  We have the ability in our work with new equipment to track down contaminants that are unusual and wrongly discharged, and to use equipment that gives us forewarning of contaminants.  We are positioned to predict exposure risks attributable to discharges to sewers and, via the biosolids, to the land.

After my commentary on A New Valuation of Biosolids, in which I reported on research estimating the “value” of elements in biosolids, one of the managers of the National Sewage Sludge Repository at Arizona State University, Dr. Rolf Halden, contacted me about his proposal that biosolids be a surrogate for human exposure. He argues that, when a contaminant is in biosolids, that contaminant mostly likely has already posed some sort of human exposure.  What an interesting idea, biosolids as a predictor of human exposures.

This highlights the notion that we ought to embark on a new program for monitoring biosolids quality, going beyond “industrial pretreatment,” to what might be called “contaminant surveillance.”  Several recent articles suggested this to me.  One was about monitoring illicit drug use in cities by testing the wastewater: Spatial differences and temporal changes in illicit drug use in Europe quantified by wastewater analysis,  A second recent article described evidence that popular sewer rehabilitation technologies have a sinister risk of pollution releases, so some new potential contaminant sources are under our noses: Stormwater Chemical Contamination Caused by Cured-in-Place Pipe (CIPP) Infrastructure Rehabilitation Activities  A third article is by an epidemiologist who had mapped the occurrence of community-spread diseases by tracking the evidence in sewage:  Estimating the Prevalence of Potential Enteropathogenic Escherichia coli and Intimin Gene Diversity in a Human Community by Monitoring Sanitary SewageThe recent Ebola outbreak similarly raised questions about how our profession might be proactive to risks from parasites and pathogens (See the MABA News Tab in our website.) Are we ready to undertake contaminant surveillance?  May be not today, but the capacity to do so is coming fast, and we might gear up. It is starting in the health field.  Bill Gates was speaking on a radio interview 5/7/15 of funding a real-time surveillance of disease outbreaks on the African continent for early warning of epidemics. He is using the power of technological breakthroughs in DNA analysis to pinpoint emerging epidemics as they occur.  Bill Gates launches network of disease surveillance centers: Centers in Africa and Asia will collect data on child mortality and help fight epidemics during outbreaks

We need to look ahead to the day that we are similarly capable of monitoring the quality of our biosolids from a pollutant and pathogen standpoint on a real time and continuous basis. The analytical equipment will be that good and that cheap. This goes beyond the task of ensuring high quality biosolids to that of a much larger mission of giving warning to exposures in our environment of potential human and environmental harm. We may even be in a position, someday, of altering our treatment processes to effectuate greater removal efficiencies for protection of our product and our customers based on sensing the character of the pollutants reaching our treatment plants. Would that not be an awesome capability!

Some of us lucky ones have been witnesses to an amazing amount of progress in the improved quality of our biosolids products over nearly four decades.  But, the job isn’t done, and we can look forward to accelerating changes.  Let us be part of creating that new future for biosolids, one in which we start fresh with a commitment akin to “industrial pretreatment” in the past, to a future in which we  Reboot for Contaminant Surveillance.