Biosolids Drying is the process of producing a fertilizer product for beneficial reuse from solids produced during municipal wastewater treatment. The drying of biosolids involves the evaporation of water to stabilize the material and produce a product for beneficial use. Thermal energy needs to be transferred to the biosolids to evaporate the water and heat the solids. Energy can be provided by combustion of fuels, re-use of waste heat or solar radiation (WEF, 2014). The most common technology for biosolids drying in the United States utilizes rotary drum dryers. In these systems, fines and crushed oversized pellets produced during the drying system are mixed with dewatered biosolids upstream of the dryer to create a 55% - 65% dry biosolid in the form of pellets. Reducing the percentage of fines generated during the drying process can potentially reduce the amount of energy required for drying. In earlier research completed by Zhang (2018) it was shown that energy modifying amendments, specifically cationic polyelectrolytes, can reduce the zeta potential of biosolids in solution and possibly promote aggregation of the fines. One of the tested amendments, polydiallyldimethylammonium chloride (PDADMAC), was also shown to increase the particle size of the biosolids in solution. In this work, a bench scale drying system was designed and developed to apply the polyelectrolyte amendments to biosolids during the mixing phase, and to gauge the impact on the pellet size distribution and the percentage of fines generated after drying. It was shown that PDADMAC, which is a high charge density cationic polyelectrolyte, had a measurable, though inconsistent, impact on pellet size when applied during the mixing phase. This work also highlights the varying characteristics of biosolids and the recycled biosolids produced during the drying process. Both PDADMAC, and polyallyamine, another cationic polyelectrolyte, when applied to biosolids during the mixing phase limited the increase in fines production as the mixing time was increased prior to drying.

This study was conducted to compare the speciation and behavior of P in soils receiving either different biosolids or inorganic fertilizer, as assessed by sequential chemical extractions, phosphate desorption, and synchrotron X-ray absorption near edge structure (XANES) spectroscopy. The objectives of this study were to i) measure the total amount of organic and inorganic phosphorus removed by chemical extraction method ii) investigate how P desorption kinetics are influenced in biosolids amended soils compared to inorganic fertilizer amended soils; and iii) perform solid state speciation of soil samples before and after chemical extraction and desorption with P K-edge XANES spectroscopy. Soil samples were analyzed that received three different rates of biosolids (16.8, 33.6, and 67.2 Mg ha-1 yr-1) and one inorganic fertilizer application (336 kg N, 224 kg P, and 112 kg K ha-1 yr-1) for 32 years. Both sequential chemical extraction and XANES analysis showed that total amount of P increased in biosolids amended soils (from 5292 to 10945 mg P kg-1) and that it increased with increasing application rate. Sequential chemical extractions showed that the labile portion of total P in inorganic fertilized soil (40 %) was larger than in biosolids applied soils (39 to 27 %). Results from both sequential chemical extraction and XANES analysis showed that NaOH extraction removed the highest amount of P from all biosolids applied soils (from 1857 to 2600 mg P kg-1). <p>The amount of desorbed P decreased as the soil:solution ratio increased from 0.005 to 100 g L-1 for both soils and the desorption was typically higher in inorganic fertilizer applied soil than in biosolids applied soil. The effect of pH on P desorption was pronounced, and desorption was higher at pH 5 than pH 7.5 for both soils. A continuous flow desorption method was also used to measure cumulative P desorption over time. Cumulative P desorption in inorganic fertilizer applied soil (894.5 mg P kg-1) was higher than in the biosolids amended soils (572.9 mg P kg-1) over 20 hr period time. First-order and parabolic diffusion kinetic equations were used to model the desorption data from the continuous flow technique. This revealed that the P desorption rate was faster (and chemically-controlled) at initial stages and slower (and diffusion-limited) at later stages. The desorption rate was much faster in inorganic fertilizer applied soil than in biosolids applied soil.<p>XANES analysis of the fractions removed in sequential chemical extractions suggested that the predominant form of P was poorly crystalline dicalcium phosphate in biosolids applied soils, and labile, sorbed forms as well as some apatite-type calcium phosphate was present in inorganic fertilizer applied soil. The combined results from sequential chemical extraction and XANES analysis indicate that P in inorganic fertilizer and biosolids-applied soils behave differently. There were larger amounts of low crystallinity phosphates in the biosolids samples, and much higher apatite content in the inorganic fertilizer amended soil.

This study was conducted to compare the speciation and behavior of P in soils receiving either different biosolids or inorganic fertilizer, as assessed by sequential chemical extractions, phosphate desorption, and synchrotron X-ray absorption near edge structure (XANES) spectroscopy. The objectives of this study were to i) measure the total amount of organic and inorganic phosphorus removed by chemical extraction method ii) investigate how P desorption kinetics are influenced in biosolids amended soils compared to inorganic fertilizer amended soils; and iii) perform solid state speciation of soil samples before and after chemical extraction and desorption with P K-edge XANES spectroscopy. Soil samples were analyzed that received three different rates of biosolids (16.8, 33.6, and 67.2 Mg ha-1 yr-1) and one inorganic fertilizer application (336 kg N, 224 kg P, and 112 kg K ha-1 yr-1) for 32 years. Both sequential chemical extraction and XANES analysis showed that total amount of P increased in biosolids amended soils (from 5292 to 10945 mg P kg-1) and that it increased with increasing application rate. Sequential chemical extractions showed that the labile portion of total P in inorganic fertilized soil (40 %) was larger than in biosolids applied soils (39 to 27 %). Results from both sequential chemical extraction and XANES analysis showed that NaOH extraction removed the highest amount of P from all biosolids applied soils (from 1857 to 2600 mg P kg-1). <p>The amount of desorbed P decreased as the soil:solution ratio increased from 0.005 to 100 g L-1 for both soils and the desorption was typically higher in inorganic fertilizer applied soil than in biosolids applied soil. The effect of pH on P desorption was pronounced, and desorption was higher at pH 5 than pH 7.5 for both soils. A continuous flow desorption method was also used to measure cumulative P desorption over time. Cumulative P desorption in inorganic fertilizer applied soil (894.5 mg P kg-1) was higher than in the biosolids amended soils (572.9 mg P kg-1) over 20 hr period time. First-order and parabolic diffusion kinetic equations were used to model the desorption data from the continuous flow technique. This revealed that the P desorption rate was faster (and chemically-controlled) at initial stages and slower (and diffusion-limited) at later stages. The desorption rate was much faster in inorganic fertilizer applied soil than in biosolids applied soil.<p>XANES analysis of the fractions removed in sequential chemical extractions suggested that the predominant form of P was poorly crystalline dicalcium phosphate in biosolids applied soils, and labile, sorbed forms as well as some apatite-type calcium phosphate was present in inorganic fertilizer applied soil. The combined results from sequential chemical extraction and XANES analysis indicate that P in inorganic fertilizer and biosolids-applied soils behave differently. There were larger amounts of low crystallinity phosphates in the biosolids samples, and much higher apatite content in the inorganic fertilizer amended soil.

The need for pathogen-free water supplies has spurred investigations into the use of ionizing radiation for the treatment of wastewater effluent and municipal biosolids. The objective of this research was to develop an electron-beam irradiation scenario to effectively eliminate microbial pathogens from municipal biosolids and wastewater effluent. The Monte Carlo N-Particle (MCNP5) radiation transport code was used to simulate the irradiation scenario. Using MCNP5, dual electron-beam sources were modeled as planar surface sources above and below a stainless steel delivery trough containing either effluent water or one of two biosolids material compositions. A dose deposition analysis was performed to assess both the planar dose distribution and 25 depth-dose curves. In addition, a density perturbation study was performed to assess the variance in the dose deposition for different mass solids concentrations. To validate the MCNP5 code for this type of application, a benchmark study was performed. Two municipal biosolids materials and water were irradiated in plastic bags on a conveyor belt using a 10-MeV electron accelerator with the exit window below the material. The experimental configuration was modeled with the MCNP5 radiation transport code. Simplified and detailed models were created and analyzed. Lastly, an economic analysis was performed to assess whether this treatment method is a financially viable alternative to current wastewater treatment methods. Processing capacity was calculated for two accelerator specifications. These capacity rates in conjunction with the operating and capital costs per dry ton to irradiate the material were compared with existing data for electron beam processing of municipal biosolids. The cost breakdown was also compared with quoted costs for existing conventional methods. The models developed showed that the use of 10MeV electron-beam technology for the treatment of wastewater effluent and municipal biosolids is effective and economically feasible. The benchmarking study illustrated the accuracy of Monte Carlo simulation for this type of application. The method development process was shown to be adaptable for various material compositions and irradiation configurations.

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Biosolids from sewage treatment plants present both problems and opportunities for society. They are rich in organic matter, nutrients and trace elements and so can be effective soil conditioners, potentially improving both soil structure and fertility. However, they commonly contain high concentrations of heavy metals, which can accumulate to toxic levels in soils receiving frequent or high dose applications. Copper (Cu) is one of the metals of chief concern because it often has high concentrations in biosolids and is capable of exerting a toxic effect on soil microbes. Limits are placed on the amounts of biosolids that can be applied to land to prevent soil accumulation of metals, but these regulatory limits are based on the total metal concentrations in soils and biosolids rather than on the portion that is ecologically active. Therefore, current regulations do not take into account the fact that much of the metal content is bound up in a way that renders it non-active, and thus poses no threat to the environment. A more environmentally relevant regulatory system would set its limits using the available portion of metals. Therefore it is important to quantify this available fraction, and to establish a method by which it can be consistently measured. To do this the nature of biosolids needs to be better understood, and the factors controlling the available fraction need to be identified. Also, it is important to determine how the available fraction may change with time. This PhD project surveyed 24 biosolids from around Australia and characterised them in terms of chemical and physical properties. Available Cu was measured using radio isotopic techniques (⁶⁴CU), a Cu²⁺ ion selective electrode, solution extraction, and other methods. A model for predicting available Cu was produced, using the total Cu concentration and the Cu²⁺ ion activity in solution extracts: Available Cu (mg/kg) = 281.5 Log Total Cu -14.9 pCu²⁺ 459 (R² = 0.806) where 'logTotal Cu' is IOglO total biosolid Cu concentration (mg/kg). A 21-month incubation experiment was conducted to monitor Cu availability over time, with the conclusion that it will remain constant if pH is maintained. Biosolidlsoil pH had a strong effect on available Cu, hence a regulatory system based on the available Cu fraction that incorporates a pH protection index is proposed. Mineralisation of organic matter did not lead to increases in available Cu, thus no evidence for the time bomb hypothesis was found. However, organic matter was found to be important for Cu sorption in some biosolids, indicating that over a longer term effects of organic mineralisation on Cu availability may be seen, and therefore longer trials (i.e. > 10 years) are needed to determine the long-term fate of biosolid Cu. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1143456 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Biosolids from sewage treatment plants present both problems and opportunities for society. They are rich in organic matter, nutrients and trace elements and so can be effective soil conditioners, potentially improving both soil structure and fertility. However, they commonly contain high concentrations of heavy metals, which can accumulate to toxic levels in soils receiving frequent or high dose applications. Copper (Cu) is one of the metals of chief concern because it often has high concentrations in biosolids and is capable of exerting a toxic effect on soil microbes. Limits are placed on the amounts of biosolids that can be applied to land to prevent soil accumulation of metals, but these regulatory limits are based on the total metal concentrations in soils and biosolids rather than on the portion that is ecologically active. Therefore, current regulations do not take into account the fact that much of the metal content is bound up in a way that renders it non-active, and thus poses no threat to the environment. A more environmentally relevant regulatory system would set its limits using the available portion of metals. Therefore it is important to quantify this available fraction, and to establish a method by which it can be consistently measured. To do this the nature of biosolids needs to be better understood, and the factors controlling the available fraction need to be identified. Also, it is important to determine how the available fraction may change with time. This PhD project surveyed 24 biosolids from around Australia and characterised them in terms of chemical and physical properties. Available Cu was measured using radio isotopic techniques (⁶⁴CU), a Cu²⁺ ion selective electrode, solution extraction, and other methods. A model for predicting available Cu was produced, using the total Cu concentration and the Cu²⁺ ion activity in solution extracts: Available Cu (mg/kg) = 281.5 Log Total Cu -14.9 pCu²⁺ 459 (R² = 0.806) where 'logTotal Cu' is IOglO total biosolid Cu concentration (mg/kg). A 21-month incubation experiment was conducted to monitor Cu availability over time, with the conclusion that it will remain constant if pH is maintained. Biosolidlsoil pH had a strong effect on available Cu, hence a regulatory system based on the available Cu fraction that incorporates a pH protection index is proposed. Mineralisation of organic matter did not lead to increases in available Cu, thus no evidence for the time bomb hypothesis was found. However, organic matter was found to be important for Cu sorption in some biosolids, indicating that over a longer term effects of organic mineralisation on Cu availability may be seen, and therefore longer trials (i.e. > 10 years) are needed to determine the long-term fate of biosolid Cu. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1143456 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004

The influence of pH on metal extractability from two sacrificial soils that received large amounts of biosolids was studied in four separate trials. The soils (Soil 1: gravelly sandy loam; Soil 2: sandy clay loam) were collected from different water treatment plants in Gauteng. Both soils had undergone significant changes in physical (organic carbon content) and chemical characteristics (pH, metal and nutrient content) due to the prolonged disposal of biosolids. A preliminary pot trial was conducted where large quantities of lime were added to the soils. Results indicated that the soils had high pH buffer capacities due to low pH and high organic matter content. An unexpected increase in the metals extracted with NH4EDTA after intensive liming lead to the performing of three further trials to shed light on the phenomenon. In the second trial lime was added to the soils at four rates (0, 12, 24, 36 tons ha-1). An increase in most NH4EDTA extractable metals was found and this was correlated with increasing absorbance values (at 465 nm) of the extracting solutions (indicating increased extractability of organic matter). In the third trial limed (27 ton ha-1) and unlimed samples were incubated over a period of 20 weeks with regular sampling intervals. The NH4NO3 extractable metals decreased significantly in the lime treated soils but the NH4EDTA extractable metals generally increased. A fourth trial was conducted due to concern regarding the increased EDTA extractable metals after liming and a possible correlation with plant metal bioavailability. The soils were incubated in pots with four lime rates (0, 12, 24, and 36 ton ha-1) and wheat and spinach grown for two months. Although similar trends as for the previous trials were obtained in terms of metal extractability, plant metal content was best correlated with NH4NO3 extraction levels. The results indicate that liming is a safe option for sacrificial soils and that NH4NO3 extractable and plant metal levels decrease with liming. The use of EDTA in metal guidelines or in soil metal content studies is discouraged due to its increased metal extractability with liming and poor correlation with plant metal content. / Thesis (PhD)--University of Pretoria, 2005. / Plant Production and Soil Science / Unrestricted

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High energy consumption in conventional wastewater treatment contributes to a large amount of greenhouse emissions and causes environmental problems such as acid rain and climate change. Many technologies, microbial electrolysis cells (MECs), electrodialysis (ED), and anaerobic digestion (AD), were developed to make wastewater treatment more efficient and economical. This thesis investigated novel MECs and ED to decrease energy consumption in wastewater treatment and recover resources from wastewater. In addition, inhibition of ammonia and acetic acid on high-solid AD was examined in this research. The multi-electrode stack design was applied in MECs to treat municipal wastewater. Rapid organic removal and minimized biosolids production were observed in the stacked MECs. In addition to municipal wastewater treatment, MECs can also recover/remove heavy metals from industrial wastewater. Various removal/recovery mechanisms of toxic heavy metals were discussed in this thesis. ED with bipolar membranes (BPMs) was examined to produce high-purity ammonium sulfate from real wastewater steams. This examination indicates valuable nutrients resources (e.g., ammonium sulfate) can be recovered from wastewater and used as land fertilizers for food production. Membrane scaling problems were also evaluated in ED systems since the formation of inorganic scalants can affect the efficiency of nutrients recovery significantly. In addition, the inhibition of ammonia and acetic acid on AD performance was incorporated in a modified anaerobic digestion model (ADM) for reliable simulation of individual biological reactions in high-solid AD. This research contributes to the body of knowledge by developing wastewater treatment technologies with less energy consumption and biosolids production. The reduction of energy consumption and biosolids production can reduce fossil fuel combustion and waste disposal. Resources, such as ammonia and heavy metals, can be recovered and reused by using the investigatory technologies. Therefore, with these developed technologies, wastewater treatment meets the goal of sustainable development and helps to establish a new green circular economy. / Thesis / Doctor of Philosophy (PhD) / High energy consumption is a main challenge in wastewater treatment. However, a large amount of energy in wastewater can be recovered and reused. The recovery of energy from wastewater can reduce energy costs, save resources, and protect the environment. This research aims to develop novel wastewater treatment technologies to save energy by recovering nutrients and producing biogas from wastewater. Bioelectrochemical systems are used to produce hydrogen gas and recover heavy metals from municipal or industrial wastewater. Electrodialysis systems are applied in ammonia recovery and fertilizer production. Anaerobic digestion systems are employed to produce methane gas as a renewable energy source from wasted sludge. These technologies reduce energy consumption in wastewater treatment and help to establish a new green circular economy for resource recovery.

O biossólido pode ser um valioso recurso ao ser utilizado em solos agrícolas; porém, um dos principais problemas de sua utilização é a presença de patógenos que podem disseminar doenças. Os principais patógenos presentes no biossólido são vírus, bactérias, protozoários e helmintos. Dentre os patógenos existentes no biossólido, os ovos de helmintos são os mais resistentes à inativação térmica e, para helmintos, os ovos de Ascaris são utilizados como indicador desses parasitas devido à comum ocorrência e resistência térmica. Dentre os processos efetivos existentes para inativar patógenos do biossólido - compostagem, secagem e tratamento térmico, digestão aeróbia termofílica, irradiação com raios beta e gama e pasteurização - este último, utilizando como fonte de calor o vapor saturado gerado a partir da queima do metano produzido em digestores anaeróbios de ETEs convencionais, é um processo de tecnologia simples, com baixo custo de implantação e operação e necessita de pequena área para implantação, sendo indicado para grandes metrópoles de países em desenvolvimento. A inativação térmica de helmintos do biossólido é o objetivo deste projeto de pesquisa. São estudadas as cinéticas de inativação térmica de ovos de Ascaris suum em água e em biossólido digerido, utilizando-se reator batelada aquecido diretamente com vapor saturado. Aplicando-se o método integral, foram determinadas a ordem das reações, as constantes específicas de morte térmica e as energias de ativação. Os ovos de Ascaris suum utilizados no trabalho foram obtidos do útero de fêmeas adultas, e o método de Yanko foi empregado para recuperação dos ovos do biossólido digerido. A inativação térmica de ovos de Ascaris em água e em biossólido digerido em processo contínuo também foi estudada por meio da modelagem matemática de um reator tubular. Os modelos propostos foram o reator tubular isotérmico com perfil de escoamento não ideal e o reator tubular com perfil axial de temperatura e escoamento tubular ideal. O primeiro foi o que melhor ajustou-se aos dados experimentais. / Biological sludge can be a valuable resource for agricultural soil conditioning. However, an important obstacle for its use is the usual presence of pathogenic organisms, capable of disease dissemination. The main occurring pathogens are virus, bacteria, protozoa and helminth. Helminth eggs are very resistant to thermal inactivation. The Ascaris lumbricoids sp. are by far the most conspicuous and resistant among helminths, reason why they have been chosen as indicator organisms for this research. The main available systems to inactivate sludge pathogens are composting, drying and thermal treatment, anaerobic thermofilic digestion, beta and gamma radiation, and pasteurization. Pasteurization through application of saturated steam, produced from burning of methane gas, generated in anaerobic digestors is a very simple technology involving low capital costs and needing relatively small areas for implementation. It can be a valuable technology to attend conditions prevailing in large metropolitan areas of industrializing countries. Thermal inactivation of helminth eggs in water and sludge is the main purpose of this investigation. Kinetics studies of thermal inactivation by saturated steam was performed using batch reactors. Application of the integral method has allowed for the determination of reaction orders, the specific constants of thermal die away as well as the activation energies. The helminth eggs (Ascaris suum) utilized have been obtained from uterus of adult females and the Yanko method was utilized for the recovery of eggs from the digested sludge. In the same way the thermal inactivation of Ascaris eggs in water and in digested sludge has been performed in continuous process by mathematical modeling of a plug flow reactor. The proposed models were the isothermic plug flow reactor with a non-ideal flow profile and with an axial temperature profile and ideal flow. The experimental data has shown a better adjustment to the isothermic plug flow reactor.