Land Application Of Biosolids Research Articles

EFFECT OF THE SYMBIOSIS BETWEEN LOLIUM MULTIFLORUM AND THE ENDOPHYTE EPICHLOË OCCULTANS ON NUTRITIONAL QUALITY OF PASTURE IN BIOSOLIDS´ AMENDED SOIL

<p>Biosolids have a high content of stable organic matter, which may be used for the remediation of marginal non-agricultural soils used for pasture production. In Argentina, the aerial biomass of <em>Lolium multiflorum</em> Lam., species is highly infected with the endophyte <em>Epichloë occultans</em>. Endophytes establish a symbiotic relationship with host plants, providing protection and resistance against different stress factors. Since land application of biosolids may rise plant stress, the objective of this work was to analyze the growth and concentration of copper (Cu) and zinc (Zn) in aerial biomass of <em>L. multiflorum</em> in symbiosis (or not) with the endophyte <em>E. occultans</em> on a sandy textured soil amended with biosolids. The association of <em>L multiflorum</em> with the endophyte produced an increase in aerial biomass only in the biosolids´ amended soil. However, the presence of the endophyte did not modify the concentration of Cu or Zn in the aerial biomass of the pasture under the experimental conditions.</p>

Impacts of molybdenum-, nickel-, and lithium- oxide nanomaterials on soil activity and microbial community structure

The nano forms of the metals molybdenum oxide (MoO3), nickel oxide (NiO) and lithium oxide (Li2O) are finding wide application in advanced technologies including batteries and fuel cells. We evaluated soil responses to nanoMoO3, nanoNiO, and nanoLi2O as some environmental release of the materials, either directly or following the land application of biosolids, is expected. Using Drummer soil (Fine-silty, mixed, superactive, mesic Typic Endoaquolls), we evaluated the impacts of the three nanometals on soil gas (N2O, CH4, and CO2) emissions, enzyme activities (β-glucosidase and urease), and microbial community structure (bacterial, archaeal, and eukaryal) in a 60 day microcosms incubation. Soil treated with nanoLi2O at 474 μg Li/g soil, released 3.45 times more CO2 with respect to the control. Additionally, β-glucosidase activity was decreased while urease activity increased following nanoLi2O treatment. While no clear patterns were observed for gas emissions in soils exposed to nanoMoO3 and nanoNiO, we observed a temporary suppression of β-glucosidase activity in soil treated with either metal. All three domains of microbial community were affected by increasing metal concentrations. This is the first evaluation of soil responses to nanoMoO3, nanoNiO, or nanoLi2O.

Risk assessment of biosolids-borne ciprofloxacin and azithromycin

Ciprofloxacin (CIP) and azithromycin (AZ) are commonly prescribed antibiotics for various infections in humans and are frequently detected in biosolids. Ecological and human health risks from biosolids-borne CIP and AZ are not well understood, but necessary for formulating policies on safe use and management of biosolids. A tiered integrated risk assessment (IRA), based on the World Health Organization (WHO) framework and the USEPA Part 503 Biosolids Rule, was conducted to assess human and ecological health risks from biosolids-borne CIP and AZ. The IRA utilized the hazard quotient (HQ) approach to evaluate risks to various receptors of concern (including humans, animals, and birds) in sixteen exposure pathways and three conservative biosolids land application scenarios. The scenarios consisted of (i) single-heavy (100 Mg ha−1) land application of biosolids containing 95th percentile concentrations of CIP or AZ (USEPA, 2009), (ii) long-term (annual for 40-y) land application of biosolids containing typical (median; USEPA, 2009) CIP or AZ concentrations, and (iii) long-term (annual for 40-y) land application of biosolids containing the 95th percentile concentrations of CIP or AZ. The unrealistically conservative screening level (Tier 1) assessment identified three pathways of potential concern: biosolids → soil → plant (CIP); biosolids → soil → soil organism (CIP and AZ); and biosolids → soil → soil organism → predator (CIP and AZ). Subsequent tier (refined; more realistic) assessments and pollutant limits (calculated based on the USEPA Part 503 Biosolids Rule) suggested negligible human and ecological health risks from biosolids-borne CIP and AZ under real-world biosolids application scenarios. Pollutant concentration limits were 12 mg CIP kg−1 and 2.2 mg AZ kg−1; suggesting that pollutant load tracking is not needed for the majority (75% for CIP and 90% for AZ) of USA biosolids. Biosolids-borne antibiotic resistance (currently not addressed in any risk assessment model) is the principal uncertainty limiting risk assessment of biosolids-borne antibiotics including CIP and AZ.

Physicochemical Properties of Biochars Produced from Biosolids in Victoria, Australia.

Some of the barriers associated with the land application of biosolids generated in wastewater treatment plants can be eliminated simply by converting the biosolids into biochar using a thermal conversion process called “pyrolysis”. In the current work, eight biosolids from four different wastewater treatment plants in southeast Melbourne, Victoria, Australia were collected and pyrolysed to produce biochars at two different temperatures (500 and 700 °C). In addition, characterisation studies were carried out on the biochars to obtain their physicochemical properties, which were subsequently compared with the properties of the parent biosolids. The major findings of the work demonstrated that biochars exhibited large decreases in DTPA-extractable metals such as Cd, Cu, and Zn, and also led to favorable changes in several chemical and physical characteristics (i.e., pH, Olsen P, electrical conductivity, and surface area) for agricultural land application compared to their original form (i.e., biosolids). Overall, the study suggests that there is great potential for converting biosolids to biochar using pyrolysis. This may not only improve the properties of biosolids for land application, but also has potential to reduce the risk to receiving environments and, furthermore, eliminate many of the costly elements associated with biosolids stockpiling and management.

Metagenomics reveal triclosan-induced changes in the antibiotic resistome of anaerobic digesters

Triclosan (TCS) is a broad-spectrum antimicrobial used in a variety of consumer products. While it was recently banned from hand soaps in the US, it is still a key ingredient in a top-selling toothpaste. TCS is a hydrophobic micropollutant that is recalcitrant under anaerobic digestion thereby resulting in high TCS concentrations in biosolids. The objective of this study was to determine the impact of TCS on the antibiotic resistome and potential cross-protection in lab-scale anaerobic digesters using shotgun metagenomics. It was hypothesized that metagenomics would reveal selection for antibiotic resistance genes (ARGs) not previously found in pure culture studies or mixed-culture studies using targeted qPCR. In this study, four different levels of TCS were continuously fed to triplicate lab-scale anaerobic digesters to assess the effect of TCS levels on the antibiotic resistance gene profiles (resistome). Blasting metagenomic reads against antibiotic/metal resistance gene database (BacMet) revealed that ARG diversity and abundance changed along the TCS concentration gradient. While loss of bacterial diversity and digester function were observed in the digester treated with the highest TCS concentration, FabV, which is a known TCS resistance gene, increased in this extremely high TCS environment. The abundance of several other known ARG or metal resistance genes (MRGs), including corA and arsB, also increased as the concentrations of TCS increased. Analysis of other functional genes using SEED database revealed the increase of potentially key genes for resistance including different types of transporters and transposons. These results indicate that antimicrobials can alter the abundance of multiple resistance genes in anaerobic digesters even when function (i.e. methane production) is maintained. This study also suggests that enriched ARGs could be released into environments with biosolids land application.

Long term carbon sequestration potential of biosolids-amended copper and molybdenum mine tailings following mine site reclamation

Management and reclamation of industrial mine sites for carbon (C) sequestration is an emerging technique for offsetting anthropogenic C emissions. Land application of municipal biosolids is an effective method for amending closed tailings storage facilities and providing the nutrients to establish a vegetative cover. Biosolids applications can influence the C sequestration potential of tailings and other mine wastes at the onset of reclamation by initiating soil development processes and enhancing primary productivity, thereby leading to increased accumulation of soil organic carbon (SOC) over time. The short term ecological benefits of biosolids applications are well understood, but the long-term (>10 years) effects of biosolids on reclaimed mine soils are under-researched. The objective of this long-term study was to determine the effects of biosolids applied in 1998 at increasing rates (0, 150 and 250 dry Mg ha−1) on the C sequestration potential of a copper and molybdenum mine tailings site in the southern interior of British Columbia, Canada that is currently undergoing reclamation to a pasture-based ecosystem. We assessed changes in C pools, plant productivity and select soil physiochemical parameters at an established research site at the Bethlehem Tailings Storage Facility over a 13-year period spanning from 1998 to 2011. Tailings total C and N concentrations increased with time and were highest when biosolids were applied at 250 Mg ha−1. Carbon pools increased with increasing biosolids application and ranged from 23 to 155 Mg C ha−1 after 13 years of reclamation. The net SOC sequestration rates (i.e. the C sequestration potential) ranged from 0.72 to 6.3 Mg C ha −1 yr −1 and were highest at the 250 Mg ha−1 application rate. The C storage efficiency was higher in the 150 Mg ha−1 treatment (0.74 Mg C stored per Mg of biosolids applied), indicating that lower application rates of biosolids are more efficient at storing C than higher application rates. Aboveground plant biomass was substantially higher on biosolid-amended tailings (6 and 6.7 Mg ha−1 for B150 and B250, respectively) compared to the unamended tailings (0.39 Mg ha−1), which suggests that the increase in C pools was a direct result of organic matter inputs from enhanced plant productivity. The tailings were naturally high in Cu and Mo, and when amended with biosolids at a rate of 250 Mg ha−1, elevated levels of Zn (as compared to federal soil quality guidelines) were detected. The unamended tailings increased in alkalinity with time, whereas the pH of the biosolid-amended tailings remained stable around neutral. This study demonstrated that a single application of biosolids can facilitate plant production and the accumulation of SOC on mine tailings for more than a decade, and supports the use of biosolids for promoting long-term C sequestration on reclaimed mine sites in similar environments.

Antibiotic-Resistant Genes and Pathogens Shed by Wild Deer Correlate with Land Application of Residuals.

The purpose of this study was to investigate genetic biomarkers of zoonotic enteric pathogens and antibiotic-resistant genes (ARGs) in the feces of white-tailed deer (Odocoileus virginianus) as related to proximity of deer to land that receives livestock manure or human waste biosolid fertilizers. Deer feces were collected in the St. Lawrence River Valley and Adirondack State Park of New York. Campylobacter spp. 16S rDNA was detected in 12 of 232 fecal samples (8 of 33 sites). Salmonellae were cultivated from 2 of 182 fecal samples (2 of 29 sites). Genetic virulence markers for Shiga-like toxin I (stx1) and enterohemolysin (hylA) were each detected in one isolate of Escherichia coli; E. coli O157 was not detected in any of 295 fecal samples. ARGs detected in deer feces included ermB (erythromycin-resistant gene; 9 of 295 fecal samples, 5 of 38 sites), vanA (vancomycin-resistant gene; 93 of 284 samples, 33 of 38 sites), tetQ (tetracycline-resistant gene; 93 of 295 samples, 25 of 38 sites), and sul(I) (sulfonamide-resistant gene; 113 of 292 samples, 28 of 38 sites). Genetic markers of pathogens and ARGs in deer feces were spatially associated with collection near concentrated animal feeding operations (CAFOs; Campylobacter spp., tetQ, and ermB) and land-applied biosolids (tetQ). These results indicate that contact with human waste biosolids or animal manure may be an important method of pathogen and ARG transmission and that deer in proximity to land-applied manure and human waste biosolids pose increased risk to nearby produce and water quality.

Wind erosion potential of a winter wheat–summer fallow rotation after land application of biosolids

Abstract Conservation tillage is a viable management strategy to control soil wind erosion, but other strategies such as land application of biosolids that enhance soil quality may also reduce wind erosion. No studies have determined the effects of biosolids on wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and biosolids fertilizer to traditional (disk) and conservation (undercutter) tillage practices during the summer fallow phase of a winter wheat-summer fallow (WW-SF) rotation in 2015 and 2016 in east-central Washington. Soil loss ranged from 12 to 61% lower for undercutter than disk tillage, possibly due to retention of more biomass on the soil surface of the undercutter versus disk tillage treatment. In contrast, soil loss was similar to or lower for biosolids as compared with synthetic fertilizer treatment. Our results suggest that biosolids applications to agricultural lands will have minimal impact on wind erosion.

Using mass struvite precipitation to remove recalcitrant nutrients and micropollutants from anaerobic digestion dewatering centrate

The primary objective of this research was to remove recalcitrant nutrients from anaerobically digested sludge dewatering centrate. A struvite precipitation methodology is proposed where salt crystals are encouraged to ballast colloidal particles through heterogeneous nucleation and subsequent crystal growth. The secondary objective was to assess presence of micropollutants in precipitates. Four biologically unique dewatering centrates were used to test the precipitation methodology on the variety of anaerobic digester configurations that can be expected from municipal wastewater treatment plant. The effect of digestion sludge retention time (2 day, 20 day) and digestion temperature (35 °C, 55 °C) on the removal of dissolved unreactive phosphorus (P) and nitrogen (N) was monitored. Averaged across all four centrates, the precipitation methodology resulted in dissolved unreactive P and N removal of 82.4% and 66.6%, respectively. Antimicrobial contaminants (triclosan, triclocarban) were observed in the precipitates at minute concentrations (<18 ng/g-dry solids). Therefore, mass struvite precipitation can provide a means of recalcitrant nutrient treatment and reactive nutrient recovery without the micropollutant burden of biosolids land application.

Antimicrobial resistance due to the content of potentially toxic metals in soil and fertilizing products.

ABSTRACTPotentially toxic metals (PTM), along with PTM-resistant bacteria and PTM-resistance genes, may be introduced into soil and water through sewage systems, direct excretion, land application of biosolids (organic matter recycled from sewage, especially for use in agriculture) or animal manures as fertilizers, and irrigation with wastewater or treated effluents. In this review article, we have evaluated whether the content of arsenic (As), cadmium (Cd), chromium (CrIII + CrVI), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), and zinc (Zn) in soil and fertilizing products play a role in the development, spreading, and persistence of bacterial resistance to these elements, as well as cross- or co-resistance to antimicrobial agents. Several of the articles included in this review reported the development of resistance against PTM in both sewage and manure. Although PTM like As, Hg, Co, Cd, Pb, and Ni may be present in the fertilizing products, the concentration may be low since they occur due to pollution. In contrast, trace metals like Cu and Zn are actively added to animal feed in many countries. In several studies, several different bacterial species were shown to have a reduced susceptibility towards several PTM, simultaneously. However, neither the source of resistant bacteria nor the minimum co-selective concentration (MCC) for resistance induction are known. Co- or cross-resistance against highly important antimicrobials and critically important antimicrobials were identified in some of the bacterial isolates. This suggest that there is a genetic linkage or direct genetic causality between genetic determinants to these widely divergent antimicrobials, and metal resistance. Data regarding the routes and frequencies of transmission of AMR from bacteria of environmental origin to bacteria of animal and human origin were sparse. Due to the lack of such data, it is difficult to estimate the probability of development, transmission, and persistence of PTM resistance.Abbreviations: PTM: potentially toxic metals; AMR: antimicrobial resistance; ARG: antimicrobial resistance gene; MCC: minimum co-selective concentration; MDR: multidrug resistance; ARB: antimicrobial resistant bacteria; HGT: horizontal gene transfer; MIC: minimum inhibitory concentration

Biochar and activated carbon act as promising amendments for promoting the microbial debromination of tetrabromobisphenol A

The increasing occurrence of tetrabromobisphenol A (TBBPA) in the environment is raising questions about its potential environmental health impacts as it has been shown to cause various deleterious effects in humans. The fact that the highest concentrations of TBBPA have been reported in wastewater sludge is concerning as effluent discharge and biosolids land application are likely a route by which TBBPA can be further disbursed to the environment. Our objectives in this study were to evaluate the effect of biochar (BC) and activated carbon (AC) in promoting the biodegradation of TBBPA, and characterize the response of anaerobic sludge microbial communities following amendments. Both carbonaceous amendments were found to promote the reductive debromination of TBBPA. Nearly complete transformation of TBBPA to BPA was observed in the amended reactors ∼20 days earlier than in the control reactors. In particular, the transformation of diBBPA to monoBBPA, which appears to be the rate-limiting step, was accelerated in the presence of either amendment. Overall, microbial taxa responding to the amendments, i.e., ‘sensitive responders’, represented a small proportion of the community (i.e., 7.2%), and responded positively. However, although both amendments had a similar effect on TBBPA degradation, the taxonomic profile of the sensitive responders differed greatly from one amendment to the other. BC had a taxonomically broader and slightly more pronounced effect than AC. This work suggests that BC and AC show great potential to promote the biodegradation of TBBPA in anaerobic sludge, and their integration into wastewater treatment processes may be helpful for removing TBBPA and possibly other emerging hydrophobic contaminants.

Is SCENA a good approach for side-stream integrated treatment from an environmental and economic point of view?

The environmental and economic benefits and burdens of including the first Short Cut Enhanced Nutrient Abatement (SCENA) into a real municipal wastewater treatment plant were evaluated using life cycle assessment (LCA) and life cycle cost (LCC). The implications of accomplishing nitrogen (N) removal and phosphorus (P) recovery via nitrite in the side stream were assessed taking into account the actual effluent quality improvement, the changes in the electricity and chemical consumption, N2O, CO2 and CH4 emissions and the effects of land application of biosolids, among others. In addition, a case-specific estimation of the P availability when sludge is applied to land, therefore replacing conventional fertilizer, was performed. Furthermore, to account for the variability in input parameters, and to address the related uncertainties, Monte Carlo simulation was applied.The analysis revealed that SCENA in the side stream is an economic and environmentally friendly solution compared to the traditional plant layout with no side-stream treatment, thanks to the reduction of energy and chemical use for the removal of N and P, respectively. The uncertainty analysis proved the validity of the LCA results for global warming potential and impact categories related to the consumption of fossil-based electricity and chemicals, while robust conclusions could not be drawn on freshwater eutrophication and toxicity-related impact categories. Furthermore, three optimization scenarios were also evaluated proving that the performance of the WWTP can be further improved by, for instance, substituting gravitational for mechanical thickening of the sludge or changing the operational strategy to the chemically enhanced primary treatment, although this second alternative will increase the operational cost by 5%. Finally, the outcomes show that shifting P removal from chemical precipitation in the main line to biologically enhanced uptake in the side stream is key to reducing chemicals use, thus the operational cost, and increasing the environmental benefit of synthetic fertilizers replacement.

Nutritional (Fe, Mn, Ni, and Cr) and growth responses of rice plant affected by perennial application of two bio-solids.

Trace toxic elements often restrict the land application of different bio-solids in agriculture. In order to evaluate the separate influence of the municipal solid waste compost (MSW), sewage sludge (SS) and combined application with inorganic fertilizers (chemical fertilizer (CF)) on nutritional (Fe, Mn, Ni, and Cr) and growth responses of rice plant, a research was conducted on paddy soil from 2013 to 2015. Obtained results showed that SS levels were superior to MSW in most studied traits. The maximum chlorophyll content (46.52), plant height (162.6cm), biomass (23.33tha-1), soil available Fe (206.26ppm), Ni concentration in the root (14.41ppm) and shoots (3.16ppm), Cr concentration in the root (12.43ppm) and grain (3.65ppm), and Mn concentration in grain (66.938ppm) belonged to SS levels, specially enriched 40tha-1, when it was added to the soil for three continuous years. The highest 1000-grain weight (29.89g), yield (6.86tha-1), harvest index (48.17%), and soil available Mn (712.7ppm), Fe, and Ni concentration in grain (107.92 and 8.79ppm, respectively) were recorded in 3years of applying the enriched 40tha-1 MSW. Accumulation of Ni in grain in critical levels and negative effects of CF treatments on toxic element entry to soil and plant were two important findings of this research that need management.

Influence of cerium oxide nanoparticles on the soil enzyme activities in a soil-grass microcosm system

Engineered nanoparticles (NPs) released in the soil, water, and air can return to the environment through the agronomic land application of biosolids, and their potential effect on agricultural ecosystems is most concerning. Soil enzyme activity, often treated as an indicator of soil quality and soil biota, is also useful in determining the sustainability of agricultural ecosystems, particularly soil physico-chemical and microbiological processes. The objective of this research was primarily to determine whether CeO2 NPs would affect soil quality and fertility by changing soil enzyme activities. The concentration and exposure time-dependent potential toxicity of CeO2 NPs on soil microorganisms was examined by testing the activity of three enzymes—urease, phosphatase, and β-glucosidase—in a soil-grass microcosm system, and estimated through specific enzyme assays. NPs were applied at different concentrations at 0, 100, 500, and 1000mg/kg soil mixtures in separated pots in which organic hard red wheat (Triticum aestivum) was grown. The effect of exposure time of NPs on soil enzyme activity was also examined through different harvest time events, by mowing the wheatgrass at weeks two, thirteen, and twenty-two and analyzing the soil enzyme activities for three cut groups, which were then compared with those in non-cut groups. Higher NP concentration above and equal to 100mg/kg was found to inhibit urease and β-glucosidase activities, and to stimulate the phosphatase activity. Specifically, the inhibition effect from CeO2 NPs on urease activity for the non-cut 1 and cut 1 groups increased from −5.07% at a 100mg/kg concentration to −13.2% at a 500mg/kg concentration to −19.91% at a 1000mg/kg concentration, compared to the treatment without CeO2 NPs. The inhibition effect from CeO2 NPs on beta glucosidase activity for the cut 2 group increased from −0.32% to −70.84% at the 100mg/kg and 1000mg/kg concentrations, while an inhibition percentage for the non-cut 2 group was between −16.89% to −50.22% at the 100mg/kg and 1000mg/kg concentrations. The non-cut and cut 1 groups exhibited the greatest effect on promotion of the phosphatase activity, with an increase from 97.46% to 131.37% to 181.45% at 100, 500, and 1000mg/kg concentrations, respectively, compared to the 0mg/kg concentration. The aging effect of CeO2 NPs indicated that a longer contact time between NPs and the soil alleviated the impact from CeO2 NPs on soil enzymes, and potentially reduced the ecotoxicity of NPs in the soil environment.

Utilization of Biosolids in Forage Production Systems in Florida

This four-page publication provides basic information about land application of biosolids to pastures and hayfields in Florida. The information contained in this document should be of interest to stakeholders, biosolids managers, students, and scientists interested in topics related to biosolids management practices and the potential benefits and risks associated with biosolid land application. Written by Maria L. Silveira, George A. O’Connor, and Joao M.B. Vendramini and published by the Department of Soil and Water Sciences.

Pilot scale high solids anaerobic digestion of steam autoclaved municipal solid waste (MSW) pulp

Steam autoclaving is an efficient method for the separation and near complete recovery of organics from MSW. The material produced by the autoclave contains a high concentration of solubilized food waste absorbed onto a lignocellulosic matrix. Reported here is the operation of a 1500 gal (5677 L) high solids anaerobic digester to digest this feedstock. Total solids (TS) reductions were high, 56%, and volatile solids (VS) and biodegradable volatile solids (BVS) reductions were 63 and 79%, respectively. Gas yields were also high, producing 248 L CH4/kg VS fed or 393 L CH4/kg VS destroyed at a methane content of 60%. Unique design elements such as hydraulic conveyance of material, in situ classification, and in-place buffering to maintain pH stability were tested and confirmed. The digestate passed all criteria for land application of biosolids in the US, but exceeded the EU limits for Cu, Ni, and Zn.

A combined reed bed/freezing bed technology for septage treatment and reuse in cold climate regions.

A combined reed bed-freezing bed (RB-FB) technology was effective at treating septage under Canadian climatic conditions over a 5-year period with average loading rates of 82-104 kg TS/m2/y. Varying hydraulic and solid loading rates as well as the increasing sludge cake with time had little to no effect on treatment efficiency, with almost complete removal of organic matter, solids, heavy metals and nutrients. Filtrate concentrations varied significantly between the freeze-thaw and growing seasons for many parameters, although the differences were not important from a treatment or reuse perspective with filtrate quality similar to a low to medium strength domestic wastewater. The potential to reuse the filtrate as a source of irrigation water will depend upon local regulations. The dewatered sludge cake consistently met biosolids land application standards in terms of pathogen and metals content, with Escherichia coli numbers declining with time as sludge cake depth increased. A combined RB-FB technology can provide a cost-effective solution for septage management in northern rural communities with potential for beneficial reuse of both the filtrate and dewatered sludge cake.

A quantitative microbial risk assessment model for total coliforms and E. coli in surface runoff following application of biosolids to grassland

In Ireland, the land application of biosolids is the preferred option of disposing of municipal sewage waste. Biosolids provide nutrients in the form of nitrogen, phosphorus, potassium and increases organic matter. It is also an economic way for a country to dispose of its municipal waste. However, biosolids may potentially contain a wide range of pathogens, and following rainfall events, may be transported in surface runoff and pose a potential risk to human health. Thus, a quantitative risk assessment model was developed to estimate potential pathogens in surface water and the environmental fate of the pathogens following dilution, residence time in a stream, die-off rate, drinking water treatment and human exposure. Surface runoff water quality data was provided by project partners. Three types of biosolids, anaerobically digested (AD), lime stabilised (LS), and thermally dried (TD)) were applied on micro plots. Rainfall was simulated at three time intervals (24, 48 and 360 h) following land application. It was assumed that this water entered a nearby stream and was directly abstracted for drinking water. Consumption data for drinking water and body weight was obtained from an Irish study and assigned distributions. Two dose response models for probability of illness were considered for total and faecal coliform exposure incorporating two different exposure scenarios (healthy populations and immuno-compromised populations). The simulated annual risk of illness for healthy populations was below the US EPA and World Health Organisation tolerable level of risk (10−4 and 10−6, respectively). However, immuno-compromised populations may still be at risk as levels were greater than the tolerable level of risk for that subpopulation. The sensitivity analysis highlighted the importance of residence time in a stream on the bacterial die-off rate.

Sorption and desorption of selected non-steroidal anti-inflammatory drugs in an agricultural loam-textured soil

Non-steroidal, anti-inflammatory drugs (NSAIDs) are widely used pharmaceutical products with analgesic and anti-inflammatory effects that are consistently detected in municipal wastewater systems and in municipal biosolids. Land application of biosolids and irrigation with reclaimed wastewater introduces these compounds into agricultural environments, which is an emerging issue of concern for ecosystem health. In this study, the sorption-desorption behaviour of four commonly consumed NSAIDs, including naproxen (NPX), ibuprofen (IBU), ketoprofen (KTF), and diclofenac (DCF), was examined in a loam textured soil exposed to either an individual-compound or a mixture of the four NSAIDs. The proportion of NSAIDs adsorbed to the soil in the mixture-compound system was 72%, 55%, 50% and 45%, for diclofenac, naproxen, ketoprofen, and ibuprofen, respectively, and differed slightly from the individual compound adsorption. Diclofenac displayed strong sorption and low desorption in both the individual-compound and mixture-compound systems. Naproxen and ibuprofen exhibited significant differences between the adsorption isotherms of the individual-compound and mixture-compound systems. Results of this study highlight differences in the sorption behaviour of NSAIDs, when present as mixtures, possibly through multilayer bonding effects or complexation with cationic metals or organo-clays from the soil. Soil organic matter (SOM) may have played a role in determining some of the interactions between the compounds but other factors associated with the mixture-compound system, such as cation bridging or multilayer cooperative adsorption. Desorption data suggests that the mechanisms involved in binding NSAIDs to the soil surface are also influence by the presence of other compounds in a mixture. A reduction in desorption was observed for all four NSAIDs in the mixture-compound system relative to the individual-compound system, but were greatest for naproxen and ibuprofen. The sorption-desorption hysteresis increased for naproxen and ibuprofen in the mixture-compound system. This study suggests that cooperative adsorption plays a role in the interaction of NSAIDs when present as mixtures rather than as individual compounds.

Impacts of Phosphorus Index Regulations and Emerging Phosphorus Recovery Technologies on Biosolids Land Application

Impacts of Phosphorus Index Regulations and Emerging Phosphorus Recovery Technologies on Biosolids Land Application