Colorado State University Pueblo – High Molecular Weight Polymers

April 10, 2013

The Influence of High Molecular Weight Polymers in Biosolids on the Presence and Fate of Anthropengenic Organic Compounds and Nutrients


Approved treated municipal waste water can be used as fertilizer on some Colorado farms. To improve transportability, this water is processed. Recently, concern was raised that this processing may have unknown environmental and health impacts by making this fertilizer’s nutrients unavailable or differently available to human crop plants, thereby contaminating the soil. Colorado State University-Pueblo researchers Dr. Chad Kinney and his graduate student Matt Dunbar, built partnerships with the local wastewater treatment plant and a leading producer of the treatment that converts the water to a fertilizer to investigate these unknown impacts. The results of their work will lead to the development of an Environmental and Health Impact Statement (E/HIS) report which could lead to important information for epidemiologists to look into past and current public health records to explain health issues – and possibly to predict what to look for in future health occurrences.

Sewage sludge from wastewater treatment facilities that meets state and federal regulatory requirements for pathogen and metal content can be classified as biosolids and land applied as an organic carbon- and nutrient-rich soil amendment for plants, primarily on agricultural soils. In this way biosolids help support sustainable agriculture by recycling nutrients and improving soil quality by enhancing the soil organic carbon content; this can improve the nutrient- and water-holding capacities of soil. Prior to land application biosolids are typically dewatered to reduce the transportation weight. To aid in dewatering, high molecular weight polymers (HMWPs) are often used to promote flocculation/ coagulation of solids. However, this practice is used without consideration of the impact it may have on factors such as availability of plant nutrients or on the fate of trace organic contaminants that are known to be present in biosolids.

A preliminary study was conducted at Colorado State University-Pueblo in 2010 in cooperation with a regional wastewater treatment plant (WWTP) to determine the influence of a commercially utilized polymer on availability of the nutrient phosphate , as well as, the fate and behavior of anthropogenic organic contaminants (AOC’s) during biosolid weathering. The availability of total leachable phosphates was greatly reduced in the biosolid prepared with polymer compared those without polymer. This difference can be largely attributed to differences in the availability of inorganic phosphate relative to organic phosphate. Anthropogenic organic contaminants is a term used to describe a diverse array of organic chemicals, such as pharmaceuticals, disinfectants, hormones, and more, that commonly enter the municipal waste stream as a result of everyday activities. Many AOCs survive the wastewater treatment process and can reside in biosolids. The initial concentration of some AOCs was greater in biosolids not receiving polymer addition as compared to biosolids amended with polymer. The fraction of leachable AOCs was enhanced in biosolids without polymer compared to those with polymer. To optimize the beneficial use of biosolid and develop best management practices, it is important to understand the availability of nutrients in biosolids. With recent reports of the uptake of some AOCs in crops it is important to consider how biosolid management practices may influence the presence and availability of AOCs.

In partnership with a local wastewater treatment plant and a leading producer of high molecular weight cationic polymers for the wastewater industry, we collaboratively designed a project to build upon the results of our preliminary study. The current study focuses on the influence of various classes of commercially available polymers on the presence and availability of the nutrients ammonium (NH4+), nitrate (NO3-), and phosphates (PO43-) and select AOCs. This project comprises the major portion of a thesis of a student in the Chemistry-MS program at CSU-Pueblo.


The seeds of this project were initially developed out of a conversation that the Chad Kinney, the project PI, had with a colleague that works for a federal agency and specialized on issues related to biosolid-amendment of agricultural soils. Dr. Kinney’s colleague mentioned that the nitrate levels in soils amended with biosolids produced by a regional WWTP were remaining high for a longer than expected time and preventing regular biosolids-amendment of the soil. A hypothesis that the use of cationic polymers and slow degradation of biosolids applied to the soil surface may be partially responsible for this phenomenon was developed.

The WWTP in question was approached to discuss this possibility. Out of this discussion a collaboration between the WWTP and Dr. Kinney was established and preliminary study developed. The WWTP provided biosolid samples prior to addition of HMWPs, samples of the HMWPs being used at the WWTP at the time, and detailed directions on how to mirror the addition of HMWPs in an industrial setting in a laboratory setting. Due to limited resources the results from the initial study were restricted to the influence of a single HMWP on phosphate and AOC content and availability in the biosolids. However, the differences observed between the biosolids samples amended with HMWPs compared to the control biosolids (no HMWPs) was dramatic. These results were provided to the partnering WWTP and disseminated at a national scientific meeting.

Following the completion of the preliminary study, the results were discussed with the director of local WWTP. Out of that discussion a new partnership was developed and an experimental design that greatly expanded specific aims of the project from the preliminary study was developed. A graduate student, Matt Dunbar, was recruited to participate in the project as his Chemistry-MS thesis project. The partnership on this project was rounded out by recruiting a leading producer of HMWPs for the wastewater industry to participate. The manufacture of HMWPs was instrumental in refining the experimental design that ultimately became the approved Thesis Plan for Matt.

Organizational Structure / Characteristics 

Dr. Kinney serves as the director for this project under the advisement of the Director of a local WWTP and a representative from the HMWP producer. Results are shared, discussed, and analyzed within this group along with the graduate student conducting the research. Because this is a graduate student thesis project it must conform to the academic requirements of the university. Therefore, there are two other faculty members from the Chemistry Department serving on the student’s thesis committee to assure quality research and data analysis.

The benefit to this project of civic engagement and community-university partnership are multi dimensional. (1) The expected results of this research project are more significant and relevant to communities worldwide. The results of this project will inform the global wastewater industry on issues that can impact their best management practices for sewage sludge/biosolids production and disposal. (2) The community partners on this project will be at the forefront of understanding the influence of HMWPs on specific characteristics of biosolids and perhaps modifying practices appropriately. (3) The research project, and therefore the student’s thesis, is more relevant and more robust as a result of partnership with a WWTP and HMWP producer. (4) The student participating in this research is engaged and takes great pride in this project in part because of the fact that his thesis research has clear real world applications and impact.

One tangible benefit of this project/partnership is the interest from the local WWTP in pursuing additional partnerships with the science and social science units at CSU-Pueblo.


1. Scholarship for Engagement Faculty Grant (Colorado Campus Compact) 9/11 – 6/12

$750 + $250 match from CSU-Pueblo

2. College of Science and Math CSU-Pueblo
$250 per semester per research student during the academic year

3. NSF-IGERT Grant 1/12 – 6/13
$2500 per semester for supplies
$5000 stipend for the Chemistry-MS student


This project is ongoing and has been underway for about 9 months. As a Chemistry-MS Thesis project, it is common for such projects to require 18-24 months to reach completion. As a Chemistry-MS thesis project this project must meet the scientific rigor and standards as assessed by the student’s thesis committee. Student learning outcomes of the Chemistry-MS are regularly assessed on an annual basis.


While civic engagement and community-based research are not wholly new at CSU-Pueblo, formally identifying projects as such is. The campus as a whole is developing an awareness and participation in these areas, particularly in service learning and community based research. These initiatives are largely being formalized and expanded with support from two US Department of Education grants and support from Colorado Campus Compact. This project and others developed under this more formalized model over the last couple of years are being identified as models for other faculty and students as well as potential community partners. We expect all of these type of activities to benefit the university moving forward as civic engagement initiatives become more central to university activities in fully realizing its mission in the region.

Excerpt from the CSU-Pueblos mission statement: As a regional comprehensive university, CSU-Pueblo takes a leadership role in enhancing the overall quality of life and economic growth in southeastern Colorado. Faculty, staff, and students provide and benefit from a wide array of community services including cultural and educational events and programs, clinical and health resources, student internships, workshops, consultations and research on community and business problems. In partnership with other community organizations, the University has committed its time and talents especially to initiatives aimed at enhancing economic development, pre-kindergarten through high school educational opportunities, and a variety of cultural activities.


Chad A. Kinney Ph.D.

Associate Professor of Chemistry
Chemistry Department
Colorado State University-Pueblo
2200 Bonforte Blvd
Pueblo, CO 81001

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