Pathogen Survey of Pulp and Paper Mill Biosolids Compared with Soils, Composts, and Sewage Biosolids

Abstract

Regulatory policies to manage land application of organic materials are risk based, with focus on the quality of these residuals. The Ontario Ministry of the Environment and Climate Change (MOECC) determined that limited information was available on pulp and paper biosolids (PPB) with respect to human enteric pathogens. To address this data gap, MOECC conducted an extensive survey (2005-2006) across Ontario to characterize the microbiological quality of PPB. Quantitative testing was performed for fecal indicators (, enterococci, ) and enteric pathogens (, , , and ) using matrix-validated methods. Comparative benchmark materials (soils and soil amendments) were analyzed concurrently for risk comparison. Results showed that detection rates in PPB were low, 5 to 25% for pathogens and <55% for . , and were found at low frequency (6-8% of samples) and at low mean concentrations (2 most probable number g dry wt., 9 oocysts g dry wt., and 7 cells g dry wt., respectively). was more frequently observed (19% of samples), with a mean of 30 cysts g dry wt. Pathogen concentrations in PPB were generally equivalent to or higher than those in soils, composts, and pelletized sewage biosolids but significantly lower than in sewage biosolids. levels exceeded standards (1000 colony-forming units g dry wt.) in one-third of samples, most often in fresh PPB rather than stored and lagoon solids. Microbial quality of PPB across all surveyed mills tended to be variable and sector- and/or site-specific but in many cases would not consistently meet Canadian federal fertilizers standards. These findings were important to inform Ontario's nutrient management regulations, supporting classification of PPB as higher pathogen risk than compost and commercial fertilizers.

Soil carbohydrate and aggregation as affected by carbohydrate composition of paper mill biosolids

“…For this study, only treatments with an application rate of 0, 30, and 60 Mg PB•ha −1 (wet weight) were considered. The 30 Mg fresh material•ha −1 corresponded to the typical annual rate applied on cropland in Québec (Hébert 2016), and those reported in Ontario (15-30 Mg dry matter•ha −1 ; Flemming et al 2017). Supplemental inorganic N as Ca-NH 4 NO 3 (45 kg N•ha −1 averaged over the years) was, however, added to the 30 Mg PB•ha −1 rate in 2004 and 2006-2008 to ensure adequate corn N nutrition.…”

Pathogen Characterization of Fresh and Stored Mesophilic Anaerobically Digested Biosolids

“…In the case of pathogens with a low frequency of detection, the inclusion of left-censored data at MDL may produce a positive bias in central tendency estimates, which produces artificially elevated (conservative) estimates (i.e., it is acknowledged that this approach may yield artificially high results for the means). In the work by Pepper et al (2010) and Flemming et al (2017): more sophisticated statistical methods were used to estimate sample means-that is, fitting the data points to a log normal distribution and using censored regression statistics (e.g., maximum likelihood estimates) to determine a potentially more accurate sample mean by predicting the values of nondetect data. Therefore, it is not surprising that mean estimates in the current study may be in some cases higher than in other studies; the approach by the current study represents a worst-case approach for estimating pathogen concentrations.…”

Crecimiento de plántulas de Vicia faba L. en mezclas de suelo con biosólidos

“…Interesantemente nuestros resultados muestran que los biosólidos que provienen de las PTAR de las industrias estudiadas ubicadas en México, tienen una concentración de metales pesados hasta diez veces menor (Bedoya-Urrego et al, 2013;Flores-Félix et al, 2014;González-Flores et al, 2017), mínima cantidad de microorganismos patógenos (Flemming et al, 2017;Hernández et al, 2017) y no incluyen metales como arsénico y mercurio, diferencias importantes con los biosólidos de las PTAR urbanas, lo anterior indica que algunos biosólidos de origen industrial son favorables para su uso en la agricultura.…”