Wastewater Biosolids Research Articles

Soil fertilization with wastewater biosolids - monitoring changes in the 'soil-fertilizer-plant' system and phosphorus recovery options.

The aim of this study is to establish changes that may occur after a prolonged application of wastewater sludge treated to biosolids, in the 'soil-fertilizer-plant' system. Thirteen experimental plots with different soil types planted with experimental crops were investigated in order to evaluate the suitability of these biosolids as soil conditioners and fertilizers. The biosolids were incorporated in soil starting in 2006 in different quantities (from 6 tons per ha) for various arrays. The rate of application was calculated on the basis of imported nitrogen and was consistent with the characteristics of the sludge, soil diversity, growing crop requirements, and other factors. In 2013 (after 7 years of land use) average soil samples from the same arrays were taken and analyzed. No chemical fertilizer was applied during the experimental period. The results show that the use of sewage biosolids as a soil improver in accordance with local legislation does not pose any serious environmental risks but can maintain and improve soil fertility and crop yield. A slight increase in Cu and Zn in plants was detected, however the content of heavy metals in all soil samples was below maximum allowable limits and no signs of phytotoxicity were observed.

Pyrolysis of wastewater biosolids significantly reduces estrogenicity

Most wastewater treatment processes are not specifically designed to remove micropollutants. Many micropollutants are hydrophobic so they remain in the biosolids and are discharged to the environment through land-application of biosolids. Micropollutants encompass a broad range of organic chemicals, including estrogenic compounds (natural and synthetic) that reside in the environment, a.k.a. environmental estrogens. Public concern over land application of biosolids stemming from the occurrence of micropollutants hampers the value of biosolids which are important to wastewater treatment plants as a valuable by-product. This research evaluated pyrolysis, the partial decomposition of organic material in an oxygen-deprived system under high temperatures, as a biosolids treatment process that could remove estrogenic compounds from solids while producing a less hormonally active biochar for soil amendment. The estrogenicity, measured in estradiol equivalents (EEQ) by the yeast estrogen screen (YES) assay, of pyrolyzed biosolids was compared to primary and anaerobically digested biosolids. The estrogenic responses from primary solids and anaerobically digested solids were not statistically significantly different, but pyrolysis of anaerobically digested solids resulted in a significant reduction in EEQ; increasing pyrolysis temperature from 100°C to 500°C increased the removal of EEQ with greater than 95% removal occurring at or above 400°C. This research demonstrates that biosolids treatment with pyrolysis would substantially decrease (removal>95%) the estrogens associated with this biosolids product. Thus, pyrolysis of biosolids can be used to produce a valuable soil amendment product, biochar, that minimizes discharge of estrogens to the environment.

Sustainable management of biosolid phosphorus: a field study

AbstractStabilized wastewater biosolids are a renewable resource for improving soil and crop quality, but their regular application can rapidly elevate soil available phosphorus (P) (e.g. Olsen‐P[OP]) leading to increased transfer of soluble reactive P (SRP) in land run‐off causing eutrophication. To assess the eutrophication risk of biosolid P recycling, 143 arable fields with different biosolid P input histories, and representing different soil type and biosolid type combinations, were sampled and their P chemistry determined. Differences in soil total P between the surveyed fields were used as the best measure of net biosolid P inputs. Rates of soil OP increase (range 3–11% of soil total P, mean 7%) were lowest on a P‐fixing soil and tended to increase more on sandy soils (6–9%) and on loamy soils receiving biosolids dosed with both iron (Fe) and lime (9–11%). Potential release of SRP to run‐off was measured as water‐extractable P (WEP) and varied widely (6–52% of soil OP). WEP concentrations were lowest on clayey soils, and where biosolids containing P‐binding elements [calcium (Ca) or Fe, but not together] were applied. The relationship between OP and WEP was therefore highly dependent on both soil type and biosolid type. However, analysis of soil P sorption parameters indicated that eutrophication risk on loamy and clayey soils was significantly reduced when OP represented <20% of the soil P sorption capacity. Our results suggest that biosolids could be more sustainably managed by matching biosolid type to soil type and P fertility status.

Wet Air Oxidation of Hydrothermal Carbonization (HTC) Process Liquid

Hydrothermal carbonization (HTC) is a promising thermochemical treatment of wet biomass. The byproduct HTC process liquid often contains a very high total organic carbon (TOC). Various toxic organic compounds (e.g., phenol, furfural, 5-HMF, etc.) can be found in HTC process liquid. As a result, the HTC process liquid often requires further treatment prior to discharge into the environment. In this study, wet air oxidation (WAO) is applied to process liquid produced from HTC of dairy manure and wastewater biosolids. Different oxygen loadings (25 and 50 atm partial pressure) were charged for WAO at 260 °C for 30 min. Furthermore, the oxidation capability of copper oxide (CuO) was evaluated at the same temperature and time. In all cases, the resulting liquid product was clear and has reduced TOC. With an increase in oxygen partial pressure, TOC is reduced up to 60% compared to the control run and 74% compared to the original HTC process liquid. The primary products in the WAO liquid product are short chain o...

Separation, detection and characterization of nanomaterials in municipal wastewaters using hydrodynamic chromatography coupled to ICPMS and single particle ICPMS.

Engineered nanoparticles (ENP) are increasingly being incorporated into consumer products and reaching the environment at a growing rate. Unfortunately, few analytical techniques are available that allow the detection of ENP in complex environmental matrices. The major limitations with existing techniques are their relatively high detection limits and their inability to distinguish ENP from other chemical forms (e.g. ions, dissolved) or from natural colloids. Of the matrices that are considered to be a priority for method development, ENP are predicted to be found at relatively high concentrations in wastewaters and wastewater biosolids. In this paper, we demonstrate the capability of hydrodynamic chromatography (HDC) coupled to inductively coupled plasma mass spectrometry (ICPMS), in its classical and single particle modes (SP ICPMS), to identify ENP in wastewater influents and effluents. The paper first focuses on the detection of standard silver nanoparticles (Ag NP) and their mixtures, showing that significant dissolution of the Ag NP was likely to occur. For the Ag NP, detection limits of 0.03μgL(-1) were found for the HDC ICPMS whereas 0.1μgL(-1) was determined for the HDC SP ICPMS (based on results for the 80nm Ag NP). In the second part of the paper, HDC ICPMS and HDC SP ICPMS were performed on some unspiked natural samples (wastewaters, river water). While nanosilver was below detection limits, it was possible to identify some (likely natural) Cu nanoparticles using the developed separation technology.

Florida Biosolids: Management and Land Application Rules

Biosolids are the liquid, semisolid, and solid fractions of the treated waste stream from a domestic wastewater treatment facility (WWTF). On August 29, 2010, the Florida Department of Environmental Protection (FDEP) formally adopted its rule for the management of wastewater biosolids, Chapter 62-640, Florida Administrative Code (F.A.C. 2010). This 6-page fact sheet from the Florida Biosolids series covers applicability of the rule, the intent of Chapter 62-640, F.A.C., land application requirements, biosolids storage, cumulative application limits, setback distances, pH, soil depth, runoff prevention, additional application site restrictions for Class B biosolids, NMPs, and special geographic areas. Written by John Hallas, Cheryl L. Mackowiak, and Ann C. Wilkie, and published by the UF Department of Soil and Water Science, October 2015. SL421/SS634: Florida Biosolids: Management and Land Application Rules (ufl.edu)

Application of self-sustaining smouldering combustion for the destruction of wastewater biosolids

Managing biosolids, the major by-product from wastewater treatment plants (WWTPs), persists as a widespread challenge that often constitutes the majority of WWTP operating costs. Self-sustained smouldering combustion is a new approach for organic waste treatment, in which the waste – the combustion fuel – is destroyed in an energy efficient manner after mixing it with sand. Smouldering has never been applied to biosolids. Column experiments, using biosolids obtained from a WWTP, were employed to identify if, and under what conditions, smouldering could be used for treating biosolids. The parameter space in which smouldering was self-sustaining was mapped as a function of key system metrics: (1) sand/biosolids mass fraction, (2) biosolids moisture content, and (3) forced air flux. It was found that a self-sustaining reaction is achievable using biosolids with water content as high as 80% (with a biosolids lower heating value greater than 1.6kJ/g). Moreover, results suggest that operator-controlled air flux can assist in keeping the reaction self-sustaining in response to fluctuations in biosolids properties. This proof-of-concept demonstrates the potential for smouldering as a new energy efficient biosolids disposal method for very wet (i.e., minimally processed) biosolids that may offer WWTPs significant operating cost savings. This study emphasizes smouldering’s usefulness as a novel waste management technique.

Triclosan adsorption using wastewater biosolids-derived biochar

Wastewater biosolids can be converted to a resource and used to remove micropollutants from wastewater.

Biochar Production and Bio-oil Upgrading by Synergistic Catalytic Pyrolysis of Wastewater Biosolids and Industrial Wastes

Biochar Production and Bio-oil Upgrading by Synergistic Catalytic Pyrolysis of Wastewater Biosolids and Industrial Wastes

Genomic and Functional Characterization of qnr-Encoding Plasmids from Municipal Wastewater Biosolid Klebsiella pneumoniae Isolates.

Municipal wastewater treatment facilities are considered to be “hotspots” for antibiotic resistance, since they conjoin high densities of environmental and fecal bacteria with selective pressure in the form of sub-therapeutic concentrations of antibiotics. Discharged effluents and biosolids from these facilities can disseminate antibiotic resistant genes to terrestrial and aquatic environments, potentially contributing to the increasing global trend in antibiotic resistance. This phenomenon is especially pertinent when resistance genes are associated with mobile genetic elements such as conjugative plasmids, which can be transferred between bacterial phyla. Fluoroquinolones are among the most abundant antibiotic compounds detected in wastewater treatment facilities, especially in biosolids, where due to their hydrophobic properties they accumulate to concentrations that may exceed 40 mg/L. Although fluoroquinolone resistance is traditionally associated with mutations in the gyrA/topoisomerase IV genes, there is increasing evidence of plasmid-mediated quinolone resistance, which is primarily encoded on qnr genes. In this study, we sequenced seven qnr-harboring plasmids from a diverse collection of Klebsiella strains, isolated from dewatered biosolids from a large wastewater treatment facility in Israel. One of the plasmids, termed pKPSH-11XL was a large (185.4 kbp), multi-drug resistance, IncF-type plasmid that harbored qnrB and 10 additional antibiotic resistance genes that conferred resistance to five different antibiotic families. It was highly similar to the pKPN3-like plasmid family that has been detected in multidrug resistant clinical Klebsiella isolates. In contrast, the six additional plasmids were much smaller (7–9 Kbp) and harbored a qnrS -type gene. These plasmids were highly similar to each other and closely resembled pGNB2, a plasmid isolated from a German wastewater treatment facility. Comparative genome analyses of pKPSH-11XL and other pKPN3-like plasmids concomitant to phylogenetic analysis of housekeeping genes from host Klebsiella strains, revealed that these plasmids are limited to a predominantly human-associated sub-clade of Klebsiella, suggesting that their host range is very narrow. Conversely, the pGNB2-like plasmids had a much broader host range and appeared to be associated with Klebsiella residing in natural environments. This study suggests that: (A) qnrB-harboring multidrug-resistant pKPN3-like plasmids can endure the rigorous wastewater treatment process and may therefore be disseminated to downstream environments; and (B) that small qnrS-harboring pGNB2-like plasmids are ubiquitous in wastewater treatment facilities and are most likely environmental in origin.

Biochar from Pyrolysis of Biosolids for Nutrient Adsorption and Turfgrass Cultivation.

At water resource recovery facilities, nutrient removal is often required and energy recovery is an ever-increasing goal. Pyrolysis may be a sustainable process for handling wastewater biosolids because energy can be recovered in the py-gas and py-oil. Additionally, the biochar produced has value as a soil conditioner. The objective of this work was to determine if biochar could be used to adsorb ammonia from biosolids filtrate and subsequently be applied as a soil conditioner to improve grass growth. The maximum carrying capacity of base modified biochar for NH3-N was 5.3 mg/g. Biochar containing adsorbed ammonium and potassium was applied to laboratory planters simulating golf course putting greens to cultivate Kentucky bluegrass. Planters that contained nutrient-laden biochar proliferated at a statistically higher rate than planters that contained biosolids, unmodified biochar, peat, or no additive. Nutrient-laden biochar performed as well as commercial inorganic fertilizer with no statistical difference in growth rates. Biochar from digested biosolids successfully immobilized NH3-N from wastewater and served as a beneficial soil amendment. This process offers a means to recover and recycle nutrients from water resource recovery facilities.

Temporal trends of perfluoroalkyl substances in limed biosolids from a large municipal water resource recovery facility

While the recycling of wastewater biosolids via land-application is a sustainable practice for nutrient recovery and soil reclamation that has become increasingly common worldwide, concerns remain that this practice may become a source of toxic, persistent organic pollutants to the environment. This study concentrates on assessing the presence and the temporal trends of 12 perfluoroalkyl substances (PFASs), pollutants of global consequence, in limed Class B biosolids from a municipal water resource recovery facility (WRRF), also know as a wastewater treatment plant. PFASs are of significant concern due to their extensive presence and persistence in environmental and biotic samples worldwide, most notably human blood samples. Class B biosolids were collected from the WRRF, prior to land-application, approximately every two to three months, from 2005 to 2013. Overall, this study found that concentrations of the 7 detectable PFAS compounds remained unchanged over the 8-year period, a result that is consistent with other temporal studies of these compounds in sewage sludges. From these analyzed compounds, the highest mean concentrations observed over the study period were 25.1 ng/g dw, 23.5 ng/g dw, and 22.5 ng/g dw for perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS), respectively, and these compounds were detected at concentrations 2.5–5 times higher than the remaining, detectable PFASs. Furthermore, it was observed that PFOS, while demonstrating no overall change during the study, exhibited a visible spike in concentration from late 2006 to early 2007. This study indicates that concentrations of PFASs in WRRFs have been stagnant over time, despite regulation.This study also demonstrates that the use of glass jars with polytetrafluoroethylene-lined lids, a common storage method for environmental samples, will not influence PFOA and PFNA concentrations in archived biosolids samples.

Quantification of methane losses from the acclimatisation of anaerobic digestion to marine salt concentrations

The research assessed losses in methane production as a result of raising digester salt concentrations to marine values, and of increasing the feedstock sulphate concentration. Acclimatisation of inoculum from a municipal wastewater biosolids digester was begun by raising the concentration of chloride salts (Na, Mg, Ca and K) to 6–9 g L−1, as initial experiments showed higher concentrations caused severe inhibition. After stable operation for four retention times salt content in the reactors and the feed was increased by 1 g L−1 every 14 days, up to 31.1 g L−1. The digesters were fed daily in semi-continuous mode and monitored for performance and stability criteria including specific methane production (SMP). SMP was 6–7% less than in controls using the same feedstock without saline addition. After steady-state conditions were achieved at high chloride salinity, magnesium chloride was partially replaced by magnesium sulphate to give a range of sulphate concentrations. Higher sulphate concentrations caused initial instability, indicated by volatile fatty acid accumulation. This subsequently reduced and stable operation was achieved at marine sulphate concentrations, but with a ∼5% loss in SMP due to interspecies substrate competition. High sulphate also affected pH, leading to gaseous H2S production proportional to the applied sulphate load.

Hyperthermophilic hydrogen production from wastewater biosolids by Caldicellulosiruptor bescii

Wastewater biosolids are abundant renewable resources that are rich in organic matter and offer a low cost potential feedstock for biohydrogen production. Relevant literature indicates that biosolids conversion rates are relatively low and therefore this option is not considered feasible. This study showed that hyperthermophilic bacteria Caldicellulosiruptor bescii could efficiently utilize biosolids as the sole carbon source and produce hydrogen (H2) for the first time in the literature. Degradability assessment studies were performed in 60 mL serum bottles at 78 ± 2 °C and the results of this study are very promising indeed. Owing to superior H2 production characteristics of C. bescii, a H2 yield of 86 mL per gram dry solids was achieved and this is the highest dark fermentative H2 yield obtained from biosolids so far. Various chromatographic methods were employed to identify the other major fermentation end products and acetic acid was found as the only major fermentation product in the biosolids reactors.

Biodegradation of benzalkonium chlorides singly and in mixtures by a Pseudomonas sp. isolated from returned activated sludge

Bactericidal cationic surfactants such as quaternary ammonium compounds (QACs) are widely detected in the environment, and found at mgkg−1 concentrations in biosolids. Although individual QACs are amenable to biodegradation, it is possible that persistence is increased for mixtures of QACs with varying structure. The present study evaluated the biodegradation of benzyl dimethyl dodecyl ammonium chloride (BDDA) singly and in the presence of benzyl dimethyl tetradecyl ammonium chloride (BDTA) using Pseudomonas sp., isolated from returned activated sludge. Growth was evaluated, as was biodegradation using 14C and HPLC-MS methods. BDTA was more toxic to growth of Pseudomonas sp. compared to BDDA, and BDTA inhibited BDDA biodegradation. The benzyl ring of [U-14C-benzyl] BDDA was readily and completely mineralized. The detection of the transformation products benzyl methyl amine and dodecyl dimethyl amine in spent culture liquid was consistent with literature. Overall, this study demonstrates the antagonistic effect of interactions on biodegradation of two widely used QACs suggesting further investigation on the degradation of mixture of QACs in wastewater effluents and biosolids.

Occurrence and Fate of Trace Contaminants during Aerobic and Anaerobic Sludge Digestion and Dewatering.

Digestion of municipal wastewater biosolids is a necessary prerequisite to their beneficial use in land application, in order to protect public health and the receiving environment. In this study, 13 pharmaceuticals and personal care products (PPCPs), 11 musks, and 17 polybrominated diphenyl ethers were analyzed in 84 samples including primary sludge, waste activated sludge, digested biosolids, dewatered biosolids, and dewatering centrate or filtrate collected from five wastewater treatment plants with aerobic or anaerobic digestion. Aerobic digestion processes were sampled during both warm and cold temperatures to analyze seasonal differences. Among the studied compounds, triclosan, triclocarban, galaxolide, and BDE-209 were the substances most frequently detected under different treatment processes at levels up to 30,000 ng/g dry weight. Comparing aerobic and anaerobic digestion, it was observed that the levels of certain PPCPs and musks were significantly higher in anaerobically digested biosolids, relative to the residues from aerobic digestion. Therefore, aerobic digestion has the potential advantage of reducing levels of PPCPs and musks. On the other hand, anaerobic digestion has the advantage of recovering energy from the biosolids in the form of combustible gases while retaining the nutrient and soil conditioning value of this resource.

Antibiotic Degradation During Thermophilic Composting

Residual antibiotics in land-applied manure and biosolids present a potential threat to public and ecological health. It remains important to determine antibiotic degradation efficiencies for manure and biosolids waste management practices and to identify conditions that enhance antibiotic degradation. The fates of the antibiotics florfenicol, sulfadimethoxine, sulfamethazine, and tylosin were studied during pilot-scale static pile thermophilic composting, and the effects of temperature and feedstock particles on antibiotic degradation rates were tested. The antibiotics were spiked into dairy manure solids and wastewater biosolids, and treatments included aerated and non-aerated manure and biosolids/wood-product (1:3 v/v) composting. Results showed no significant differences between aerated and non-aerated treatments; on average, ≥85, ≥93, and ≥95 % antibiotic degradation was observed after 7, 14, and 21 days of composting. Greater antibiotic degradation was observed in manure compost compared to biosolids compost for florfenicol (7, 14, 21, 28 days) and tylosin (14, 28 days); however, there was no significant difference for sulfadimethoxine and sulfamethazine. Peak temperatures were 66–73, and ≥55 °C was maintained for 6–7 days in the biosolids compost and 17–20 days in the manure compost. Bench-scale experiments conducted at 25, 55, and 60 °C showed that lower temperature decreased degradation of the sulfonamides and tylosin in both feedstocks and florfenicol in the biosolids. The presence of compost particles increased antibiotic degradation, with time to 50 % degradation ≤2 days in the presence of solids (60 °C) compared to no degradation in their absence. These results indicate that thermophilic composting effectively degrades parent antibiotic compounds in manure and biosolids.

Wastewater Bio-solids Management for Fertilizer Quality Using Co- composting Process

Co-composting process can be acquired by combining organic fraction of municipal solid waste (OFMSW) with sewage sludge (SS) and mature compost (MC) as enhancement and bulking agent to overcome the problems of municipal solid waste and wastewater treatment plants besides the finally produced fertilizer usage for agriculture and horticulture. The effects of different mixture ratios of (OFMSW), (SS) and (MC) on the performance of composting process were investigated in this study. Piles of about 10 kg were prepared by mixing OFMSW, SS and MC in three different ratios (w/w) [OFMSW: SS: MC= 3:1:1, 3:2:1, and 3:3:1]. Results showed that the pile [3:1:1] was most beneficial to composting. The final compost products contained a C/N ratio (12.17), nitrification index (N-NH4/N-NO3) (0.2), organic matter degradation (36%), N content (1.75%), and Germintation Index (GI) 77.4%. Final compost showed low amounts of heavy metals, and significant reduction of pathogens indicating mature and stable bio-mass
 

Effect of a Trace Element Addition Strategy on Volatile Fatty Acid Accumulation in Thermophilic Anaerobic Digestion of Food Waste

A trace element (TE) supplementation strategy previously shown to be effective in mesophilic conditions was tested for thermophilic digestion of source segregated domestic food waste. Inoculum from a mesophilic anaerobic digester treating municipal wastewater biosolids was successfully acclimated to thermophilic temperature (55 °C) with food waste as a substrate. Four laboratory-scale digesters were maintained at a loading of 2 g VS l−1 day−1 with one pair receiving TE supplementation. Two more pairs of digesters were incrementally loaded to 3 and 4 g VS l−1 day−1, respectively, and also received TE. All digesters performed well for the first 3–4 months of operation, but volatile fatty acid (VFA) concentrations in those without TE showed no recovery from an initial small accumulation. On continued operation, VFA concentrations increased in all digesters, especially those at higher loading rates or without TE supplementation, reaching >30 g l−1. Under these meta-stable conditions, a deliberate disturbance to daily feeding (cessation then resumption) led to acetic acid accumulation, a fall in pH and a sharp increase in the ratio of partial to intermediate alkalinity. Increases in VFA corresponded to an increasing total ammonia nitrogen concentration which appeared to become inhibitory at ~2,500 mg N l−1. While TE supplementation delayed the onset and reduced the rate of VFA accumulation, it was unable to sustain stable digestion of this substrate in thermophilic conditions.

Fate of Engineered Nanomaterials in Wastewater Biosolids, Land Application, and Incineration

Laboratory experiments were conducted using two types of well characterized ENMs, including ENMs of similar size but different surface functional group and ENMs contained in consumer products. A sorption protocol was developed to study the sorption behaviors of hydrophobic, cationic organic molecules and ionic silver on fresh and freeze dried biomass. Partition coefficients of model ENMs with wastewater biomass were determined in a series of batch experiments. In order to assess the occurrence of ENMs in biosolids and biosolids amended soils, field samples were collected from WWTPs, a set of EPA biosolids composite samples and full scale biosolids handling facilities. ENMs were found to be present in biomass, biosolids and soils receiving land-application of biosolids. The most common ENM observed was titanium dioxide. Other metallic particles in micro meter size were identified in biosolids, including precious metals such as gold and silver. This study is among the first to conduct in-depth and extensive characterization of metallic materials in biosolids, using scanning (SEM) and transmission (TEM) electron microscopy. To support these full-scale observations that ENMs accumulate in biomass, the laboratory work explored ways to predict the presence of ENMs in biosolids in the future as more ENMs are used by industry, commercial sectors and residences. This title belongs to WERF Research Report Series . ISBN: 9781780405490 (eBook)