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The phosphate adsorption mechanisms of SA-0.4La@De involved electrostatic interactions, ligand exchange, and the formation of La–P complexes.

Sewage sludge (SS) is increasingly used as an environment functional material to reduce or control pollution and improve plant growth because of the large amounts of carbon and essential plant nutrients in it. To achieve the best application results, it is essential to comprehensively review recent progress in SS utilization. This review aims to fill the gaps in knowledge by describing the properties of SS, and its usage as adsorbents, catalysts and fertilizers, and certain application mechanisms. Although SS generates several benefits for the environment and humans, many challenges still exist to limit the application, including the risks posed by potentially toxic substances (e.g., heavy metals) in SS. Therefore, future research directions are discussed and how to make SS applications more feasible in terms of technology and economy.

Forward osmosis (FO) considered as a promising separation process for nutrient enrichment in wastewater, is attracting increasing interest in integration with chemical precipitation and other technologies for recovering nutrients in wastewater treatment. In the chapter, the processes of nutrients recovery via FO-based systems are introduced in terms of mechanisms and influencing factors. Additionally, the key challenges related to the recovery systems discussed and some approaches are proposed to resolve these challenges. Future roadmap for future research and development on the nutrients recovery using FO-based systems are identified. Compared to aerobic FO-based systems, anaerobic FO-based processes need more investigations of their integrations’ efficiency in the context of nutrient recovery from wastewater. Emphasis is given to carry out more economic assessment and pilot- and plant-scale evolutions of the recovery systems, which makes the nutrients recovery via FO-based technologies more sustainable in wastewater treatment.

Due to large quantity and containing rich resources (e.g., chemical energy, metals, fresh water and nutrients), recovery resources from municipal and industrial wastewaters can be considered where resource recovery economies can be applied. Simultaneously, resource recovery during wastewater treatment will make treatment processes more economically viable and compliant to increasingly tight environmental regulations. Bioelectrochemical system (BES) has been emerged as a platform technology to recover resources from wastewater treatment. In this chapter, a comprehensive and critical review of resource recovery via BES from wastewater is conducted. The basic information of BES as well as the processes of resource recovery through BES at the laboratory- and plant-scale are introduced. Furthermore, the current challenges related to the BES applications for the resource recovery and the possible development directions are discussed.

This paper is to explore the use of rural solid waste (RSW) for pyrolysis-gasification-combustion in pilot plant scale aiming at sustainable management of rural waste in remote areas. Based on the experimental data obtained during pilot scale operation, the temperature in the furnace needs to be kept at least at 600 °C through analyzing the pyrolysis weight loss of the main combustibles in the RSW. Besides, the effects of the air supply method and ventilation rate on the pilot plant performance were explored. Results indicate that the active air supply method positively contributes to the performance of the pilot plant. The plant processed 10 t RSW/d, producing 12.82 g/Nm

As a clean energy carrier, hydrogen is a promising alternative to fossil fuel so as the global growing energy demand can be met. Currently, producing hydrogen from biowastes through fermentation has attracted much attention due to its multiple advantages of biowastes management and valuable energy generation. Nevertheless, conventional dark fermentation (DF) processes are still hindered by the low biohydrogen yields and challenges of biohydrogen purification, which limit their commercialization. In recent years, researchers have focused on various advanced strategies for enhancing biohydrogen yields, such as screening of super hydrogen-producing bacteria, genetic engineering, cell immobilization, nanomaterials utilization, bioreactors modification, and combination of different processes. This paper critically reviews by discussing the above stated technologies employed in DF, respectively, to improve biohydrogen generation and stating challenges and future perspectives on biowaste-based biohydrogen production.

In the last few years, greenhouse gases (GHGs) have accumulated in the atmosphere at an alarming rate due to frequent industrial and manufacturing activities. As a result, global warming is being aggravated and hugely undermining the sustainable development of many societies. Technologies to mitigate climate change have spurred in recent years. In this chapter, the sequestration processes of GHGs are reviewed, in which the postcombustion capture and chemical looping systems are highlighted. The captured GHGs exhibit great potential for conversion into bioproducts with high market/economic value. The chemistry of GHG mitigation is also discussed along with the role of inorganic compounds and metals in mitigating GHG emissions. The importance of naturally occurring, low-cost materials and nanomaterials for reducing GHG emissions was elaborated. Besides, the model developed for GHG mitigation is presented. Future work on GHG mitigation is discussed in detail as well as possible current challenges such as economic analysis.

Wastewater contains a significant amount of recoverable nitrogen. Hence, the recovery of nitrogen from wastewater can provide an option for generating some revenue by applying the captured nitrogen to producing bio-products, in order to minimize dangerous or environmental pollution consequences. The circular bio-economy can achieve greater environmental and economic sustainability through game-changing technological developments that will improve municipal wastewater management, where simultaneous nitrogen and energy recovery are required. Over the last decade, substantial efforts were undertaken concerning the recovery of nitrogen from wastewater. For example, bio-membrane integrated system (BMIS) which integrates biological process and membrane technology, has attracted considerable attention for recovering nitrogen from wastewater. In this review, current research on nitrogen recovery using the BMIS are compiled whilst the technologies are compared regarding their energy requirement, efficiencies, advantages and disadvantages. Moreover, the bio-products achieved in the nitrogen recovery system processes are summarized in this paper, and the directions for future research are suggested. Future research should consider the quality of recovered nitrogenous products, long-term performance of BMIS and economic feasibility of large-scale reactors. Nitrogen recovery should be addressed under the framework of a circular bio-economy.

This study describes the photodegradation of chloramphenicol (CAP) in micro-polluted water with a thin-layer inclined plate reactor. Under simulated sunlight irradiation, the effect of reaction parameters including solution pH, initial CAP concentration, and co-existed humic acid (HA) or chloride was evaluated. The photodegradation of CAP was independent of initial pH in the range of 6.0–9.0, but sharply decreased by 25.5% with the increase of initial CAP concentration from 0.4 to 1.0 mg/L. The presence of HA exhibited a significant inhibitory effect, while Cl− promoted the photoreaction. In this study, CAP was degraded through both direct and indirect photolysis, in which 1O2 was the main reactive species responsible for the indirect route. Its steady-state concentration in the micro-polluted water was determined to be 1.40 × 10−13 mol/L. Transformation intermediates were identified to propose the degradation pathway of CAP, which substantially met the density functional theory (DFT) calculation results. Moreover, four other pharmaceuticals including tetracycline, doxycycline, oxytetracycline, and minocycline were also successfully photodegraded during 5 h irradiation. Therefore, the designed circulatory thin-layer inclined plate reactor is suggested to be effectively applied to the decontamination of organic micro-polluted water.

This study aimed to assess the impacts of organic loading rate (OLR) (435–870 mgCOD/L·d) on nutrients recovery via a double-chamber microbial fuel cell (MFC) for treating domestic wastewater. Electricity generation was also explored at different OLRs, including power density and coulombic efficiency. Experimental results suggested the MFC could successfully treat municipal wastewater with over 90% of organics being removed at a wider range of OLR from 435 to 725 mgCOD/L·d. Besides, the maximum power density achieved in the MFC was 253.84 mW/m2 at the OLR of 435 mgCOD/L·d. Higher OLR may disrupt the recovery of PO43−-P and NH4+-N via the MFC. The same pattern was observed for the coulombic efficiency of the MFC and its highest value was 25.01% at the OLR of 435 mgCOD/L·d. It can be concluded that nutrients and electrical power can be simultaneously recovered from municipal wastewater via the dual-chamber MFC.

© Springer-Verlag GmbH Germany, part of Springer Nature 2019. Amagnesia–pullulan (MgOP) composite has been developed to remove phosphate from a synthetic solution. In the present study, the removal of phosphate by MgOP was evaluated in both a batch and dynamic system. The batch experiments investigated the initial pH effect on the phosphate removal efficiency from pH 3 to 12 and the effect of co-existing anions. In addition, the adsorption isotherms, thermodynamics, and kinetics were also investigated. The results from the batch experiments indicate that MgOP has encouraging performance for the adsorption of phosphate, while the initial pH value (3–12) had a negligible influence on the phosphate removal efficiency. Analysis of the adsorption thermodynamics demonstrated that the phosphate removal process was endothermic and spontaneous. Investigations into the dynamics of the phosphate removal process were carried out using a fixed bed of MgOP, and the resulting breakthrough curves were used to describe the column phosphate adsorption process at various bed masses, volumetric flow rates, influent phosphate concentrations, reaction temperatures, and inlet pH values. The results suggest that the adsorption of phosphate on MgOP was improved using an increased bed mass, while the reaction temperature did not significantly affect the performance of the MgOP bed during the phosphate removal process. Furthermore, higher influent phosphate concentrations were beneficial towards increasing the column adsorption capacity for phosphate. Several mathematic models, including the Adams–Bohart, Wolboska, Yoon–Nelson, and Thomas models, were employed to fit the fixed-bed data. In addition, the effluent concentration of magnesium ions was measured and the regeneration of MgOP investigated.

Microbial fuel cell (MFC) is currently considered a promising technology for wastewater treatment. This study aims to evaluate the feasibility of a double-chamber MFC in terms of: (i) operating mode (batch mode, self-circulation mode, single-continuous mode) of anolyte on the nutrient accumulation in the catholyte, (ii) aeration conditions (anode effluent with aeration supplied in catholyte; anode effluent without aeration supplied in catholyte; cathode effluent with aeration supplied in catholyte and cathode effluent without aeration supplied in catholyte) on the nutrient recovery and (iii) types of separators (cation exchange membrane (CEM), forward osmosis (FO), and nonwoven (NW)) to remove nutrients toward their recovery from municipal wastewater. Results showed that there was no negligible increase in the phosphate concentration of the catholyte at the three different modes but accumulation of ammonium. At different aeration conditions, nutrients can be recovered by chemical precipitation at high pH generated by the MFC itself. Basically, phosphate was removed by microbial absorption and recovered by chemical precipitation while ammonium was accumulated by current generation and recovered as precipitates. It was found that double-chamber MFC with the CEM as the separator reported the best nutrients removal with >97.58% of NH4+-N and >94.9% of PO43−-P removed/recovered, followed by the MFC with the nonwoven and FO membrane, respectively. Thus, the double-chamber MFC is feasible for recovering nutrients in a comprehensive bioelectrochemical system.

A novel La-incorporated nanostructured ternary (hydr)oxides adsorbent (MALZ) was prepared and employed for enhanced phosphate removal in this study. The results of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicated that MALZ presented an amorphous surface with Mg, Al and La homogeneously dispersed on the outer region of zeolite. Effective phosphate removal was obtained over a wide pH range of 4–10 and the equilibrium pH after phosphate adsorption was in near neutrality. A relatively fast adsorption of phosphate was observed in the kinetics experiment, and the maximum adsorption capacity of MALZ (12.5 wt% La) was determined at 80.8 mg P/g at pH 6.6 in the equilibrium adsorption isotherm study. The coexisting anions (e.g., Cl−, SO42− and NO3−) had insignificant effects on phosphate adsorption. The adsorption–desorption experiment suggested that MALZ could be regenerated by 0.5 M NaOH solution and maintained 75.8% of its initial phosphate adsorption capacity at the fourth adsorption–desorption cycle. The combined results of zeta potential analysis, SEM, XRD and X-ray photoelectron spectroscopy demonstrated that electrostatic attraction, ligand exchange of surface hydroxyl groups by phosphate and the complexation of forming inner-sphere complex (LaPO4·xH2O) were the main adsorption mechanisms. Furthermore, La played a key role in the complexation of phosphate, while the introduction of Mg and Al further facilitated the dispersion of La and enhanced the surface charge of the adsorbent.

In this study, a laboratory-scale sequencing batch reactor (SBR) equipped with aerobic granular sludge (AGS) technology was continuously operated for 220 days to remove ammonium from an existing landfill leachate. The ammonium removal was characterized by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) technology. This method helped to analyze the long-term community structural stability of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and denitrifying bacteria (DB) throughout the experiment. Simultaneously, 16S rRNA gene cloning and sequencing analysis identified the dominant species of different microbial species. Experimental results confirmed that ammonium removal was inhibited at the high nitrogen loading rate (NLR) stage while the low NLR stage achieved satisfactory ammonium removal. Moreover, the findings demonstrated that functionally stable wastewater treatment bioreactors facilitated the occurrence of stable microbial community structures.

Nutrients recovery has become a meaningful solution to address shortage in the fertilizer production which is the key issue of nations' food security. The concept of municipal wastewater is based on its ability to be a major potential source for recovered nutrients because of its vast quantity and nutrient-rich base. Microbial fuel cell (MFC) has emerged as a sustainable technology, which is able to recover nutrients and simultaneously generate electricity. In this study a two-chambered MFC was constructed, and operated in a continuous flow mode employing artificial municipal wastewater as a substrate. The effects of hydraulic retention time (HRT) on the recovery of nutrients by MFC were studied. The COD removal rates were insignificantly influenced by varying HRT from 0.35 to 0.69 d, that were over 92%. Furthermore, the recovery rate of nutrients was insignificantly affected while increasing the HRT, which fluctuates from 80% to 90%. In contrast, the maximum power generation declined when HRT increased and the lowest one was 510.3 mV at the HRT of 0.35 d. These results demonstrate that the lab-scale double chamber MFC using municipal wastewater as the substrate can provide a highly effective removal strategy for organic matter, nutrients recovery and electricity output when operating at a specific HRT.

The magnesia–pullulan composite (MgOP) achieved effective fluoride removal in previous research. In the present study, an acid-base titration experiment was conducted to investigate the properties of MgOP surface and further explore the mechanism of fluoride adsorption on MgOP. Results showed that the presence of chloride ions could improve fluoride adsorption on MgOP; however, additional nitrate ions had negligible impacts. A diffuse layer model and chemical equilibrium software (Visual MINTEQ 3.1) were used to simulate the acid-base titration data. The effects of initial pH values on the rate of fluoride uptake by MgOP were also studied. Moreover, aluminum salts were added to the fluoride solution with MgOP for the pH neutralization of treated water, in which aluminum chloride was preferred.

Wastewater has been investigated as a source for nutrient recovery for two reasons: firstly it contains a high concentration of nutrients; and secondly, it exists in large quantities. Recovering nutrient from wastewater can minimize the environmental footprint of wastewater treatment; simultaneously, the recovered nutrient can be added to fertilizer production to ensure food security. The membrane technique integrated with chemical and biological processes as a membrane hybrid system is a promising method to recover nutrient from wastewater since the membrane can enrich nutrient. It can subsequently increase the technical and economic feasibility of the nutrient recovery process. For this reason, this paper comprehensively and critically reviews the current state of the membrane hybrid system for nutrient recovery from wastewater. Membrane hybrid systems consisting of membrane-based hybrid systems and membrane bioreactor (MBR)-based hybrid systems are explained with reference to their general features, such as mechanisms and processes. Furthermore the advantages and challenges of the membrane hybrid systems are compared as well as their economic feasibility. Future research avenues into membrane hybrid systems are suggested and what can the system more accessible.

© 2019 Elsevier Ltd In the present study, a dual-compartment microbial fuel cell (MFC) was constructed and continuously operated under different influent concentrations of ammonium-nitrogen (5–40 mg/L). The impacts of ammonium on organics removal, energy output and nutrient recovery were investigated. Experimental results demonstrated that this MFC reactor achieved a CDO removal efficiency of greater than 85%. Moreover, excess ammonium concentration in the feed solution compromises the generation of electricity. Simultaneously, the recovery rate of phosphate achieved in the MFC was insignificantly influenced at the wider influent ammonium concentration. In contrast, a high concentration of ammonium may not be beneficial for its recovery.

Nitrogen removal is crucial in wastewater treatment process as excessive nitrogen content could result in eutrophication and degradation of aquatic ecosystems. Moreover, to satisfy the fast-growing need of fertilizers due to an increase in human population, recovering nitrogen from wastewater is of the most sustainable approach. Currently, the membrane technique integrated with biological processes namely bio-membrane based integrated system (BMIS) is a promising technology for recovering nitrogen from wastewater, including osmotic membrane bioreactors, bioelectrochemical systems and membrane photobioreactors. In this review study, the nitrogen recovery in different BMHSs, the role of operational parameters and the nitrogen recovery mechanism were discussed. Apart from this, the implementation of nitrogen recovery at pilot- and full-scale was summarized. Perspectives on the major challenges and recommendations of the BMIS for the nitrogen recovery in wastewater treatment were proposed, in which the integrated technologies and more scale-up studies regarding nitrogen recovery by the BMISs were also highlighted and recommended.

The world’s increasing population means that more food production is required. A more sustainable supply of fertilizers mainly consisting of phosphate is needed. Due to the rising consumption of scarce resources and limited natural supply of phosphate, the recovery of phosphate and their re-use has potentially high market value. Sewage has high potential to recover a large amount of phosphate in a circular economy approach. This paper focuses on utilization of biological process integrated with various subsequent processes to concentrate and recycle phosphate which are derived from liquid and sludge phases. The phosphate accumulation and recovery are discussed in terms of mechanism and governing parameters, recovery efficiency, application at plant-scale and economy.

This study is based on the use of MgOP to treat solution containing fluoride and phosphate for adsorption. The characteristics of MgOP before and after adsorption were analyzed by XRD, FTIR, SEM and EDX. The experimental parameters included adsorbent dose, contact time, initial pH of solution, initial concentration of ions and the adding order of ions. The optimized adsorbent dose and contact time are 2 g L−1 and 60 min respectively. It is observed that the removal efficiency of fluoride and phosphate ions is hardly affected at the broad range of pH (2 to 12). The presence of fluoride and phosphate ions affects the adsorption rates of another one and the main existing forms of phosphate in domestic wastewater have no significant effects on the defluoridation capacity of MgOP. Besides, it is seen that the adding order of ions greatly influences the adsorption capacities of MgOP for fluoride and phosphate ions. The Langmuir isotherm and pseudo second-order kinetic models are observed to describe the adsorption processes of fluoride in the single- and multi-adsorbate systems. Intra-particle diffusion model with greater R2 is showed to explain the process of the fluoride adsorption. Also, the negative values of ΔG0 reveal that the adsorption processes of fluoride and phosphate ions in the single- and multi-adsorbate systems are feasible and spontaneous.

A magnesia-pullulan composite (MgOP) was prepared by chemical sol-gel method and utilized for the simultaneous removal of fluoride and phosphate in a continuous fixed-bed column. A series of dynamic adsorption experiments were conducted to explore the impacts of different factors on the dynamic adsorption of fluoride and phosphate in the single- and binary-adsorbate systems, including bed mass, flow rate, temperature, inlet adsorbate concentration, influent pH and coexisting anions. The results demonstrated that the adsorption capacities of fluoride and phosphate ions were 6.21 and 7.76 mg/g, respectively, at the optimal conditions (i.e., 6 g of bed mass and 0.48 L/h of flow rate), when influent fluoride and phosphate concentrations were fixed at 10 mg/L. An increased bed mass had a negative effect on the simultaneous adsorption of fluoride and phosphate on MgOP. In contrast, increasing the volumetric flow rate facilitated the removal of fluoride and phosphate from an aqueous solution in the binary-adsorbate system. Besides, the MgOP can be effectively regenerated by calcination with high stability. The column adsorption of fluoride and phosphate in the binary-adsorbate system were well described by the Thomas model. In conclusion, the present study provides insight into the simultaneous removal of fluoride and phosphate through adsorption.

The recovery of fertilizer-used nutrients from wastewater is a sustainable approach for wastewater management and helping social sustainability. This is especially the case given the strict discharge requirements and shortages existing in nutrients supply. Recognizing that wastewater is a very useful resource and the value of recycled nutrients has made researchers consider the recovery of nutrients from wastewater. This review described the current technologies used to recover nutrients in wastewater treatment and their mechanisms, including chemical methods, biological technologies, membrane systems and advanced membrane systems. Also, an economic analysis of these nutrient recovery systems was discussed and compared them in terms of positive and negative aspects. The economic feasibility of recovered nutrients was investigated. Finally, future perspectives expects some possible research directions regarding recovery system which can be more economically accessible for wastewater treatment, in which the osmotic membrane bioreactors (OMBR) and bioelectrochemical systems (BES)-based hybrid systems are highly recommended.

Immobilizing La(OH)3 nanoparticles (NPs) to porous hosts has been widely applied to inhibiting their inherent aggregation as well as the subsequent low utilization efficiency of La. In this study, a series of rice husk biochars (RHBCs) with high mesoporous rates were prepared and the effects of host pore structure and point of zero charge (pHpzc) on phosphate adsorption by La-modified RHBCs was particularly focused. Characterization results confirmed that La(OH)3 NPs were both confined in the pore channel and external surface of RHBCs. Adsorption kinetics and isotherms showed that La-modified RHBCs with higher mesoporous rates of the host showed a faster adsorption rate and La-modified RHBCs exhibited superior La utilization efficiency than many reported La-incorporated adsorbents. Phosphate could be effectively captured over a wide pH of 3–10 due to the high pHpzc of La-modified RHBCs. Moreover, the La-modified RHBCs showed satisfactory affinity towards phosphate in the presence of coexisting anions and the phosphate adsorption by La-RHBC9 was enhanced in the presence of Ca2+, while it was inhibited in the presence of Mg2+. The mesoporous structure of RHBCs strengthened the stability of La-modified RHBCs and weakened the inhibition of coexisting humic substances on phosphate adsorption through the “shielding effect”.

© 2018 Elsevier Ltd The growing global population's demand for ammonium has triggered an increase in its supply, given that ammonium plays a crucial role in fertilizer production for the purpose of food security. Currently, ammonia used in fertilizer production is put through what is known as the industrial Haber Bosch process, but this approach is substantially expensive and requires much energy. For this reason, looking for effective methods to recover ammonium is important for environmental sustainability. One of the greatest opportunities for ammonium recovery occurs in wastewater treatment plants due to wastewater containing a large quantity of ammonium ions. The comprehensively and critically review studies on ammonium recovery conducted, have the potential to be applied in current wastewater treatment operations. Technologies and their ammonium recovery mechanisms are included in this review. Furthermore the economic feasibility of such processes is analysed. Possible future directions for ammonium recovery from wastewater are suggested.

© 2017 Elsevier Ltd A magnesia-pullulan composite (MgOP) was previously shown to effectively remove fluoride from water. In the present study, a continuous fixed-bed column was used to examine the application of the composite at an industrial scale. The influencing parameters included bed mass (4.0, 6.0 and 8.0 g), influent flow rate (8, 16 and 32 mL/min), inlet fluoride concentration (5, 10 and 20 mg/L), reaction temperature (20, 30 and 40 °C), influent pH (4, 7 and 10) and other existing anions (HCO3−, SO42−, Cl− and NO3−), through which the breakthrough curves could be depicted for the experimental data analysis. The results indicated that MgOP is promising for fluoride removal with a defluoridation capacity of 16.6 mg/g at the bed mass of 6.0 g, influent flow rate of 16 mL/min and inlet fluoride concentration of 10 mg/L. The dynamics of the fluoride adsorption process were modeled using the Thomas and Yan models, in which the Yan model presented better predictions for the breakthrough curves than the Thomas model. Moreover, the concentration of magnesium in the effluent was monitored to determine Mg stability in the MgOP composite. Results indicated the effluent concentration of Mg2+ ions could be kept at a safe level. Calcination of fluoride-loaded MgOP effectively regenerated the material.

Phosphate plays an irreplaceable role in the production of fertilizers. However, its finite availability may not be enough to satisfy increasing demands for the fertilizer production worldwide. In this scenario, phosphate recovery can effectively alleviate this problem. Municipal wastewater has received high priority to recover phosphate because its quantity is considerable. Therefore, phosphate recovery from municipal wastewater can bring many benefits such as relieving the burden of increasing production of fertilizers and reduction in occurrence of eutrophication caused by the excessive concentration of phosphate in the released effluent. The chemical processes are the most widely applied in phosphate recovery in municipal wastewater treatment because they are highly stable and efficient, and simple to operate. This paper compares chemical technologies for phosphate recovery from municipal wastewater. As phosphate in the influent is transferred to the liquid and sludge phases, a technical overview of chemical phosphate recovery in both phases is presented with reference to mechanism, efficiency and the main governing parameters. Moreover, an analysis on their applications at plant-scale is also presented. The properties of recovered phosphate and its impact on crops and plants are also assessed with a discussion on the economic feasibility of the technologies.

The application of a novel coupled process with oxalate washing and subsequent zero-valent iron (ZVI)/Air treatment for remediation of arsenic contaminated soil was investigated in the present study. Oxalate is biodegradable and widely present in the environment. With addition of 0.1 mol L(-1) oxalate under circumneutral condition, 83.7% and 52.6% of arsenic could be removed from a spiked kaolin and an actual contaminated soil respectively. Much more oxalate adsorption on the actual soil was attributed to the higher soil organic matter and clay content. Interestingly, oxalate retained in the washing effluent could act as an organic ligand to promote the oxidation efficiency of ZVI/Air at near neutral pH. Compared with the absence of oxalate, much more As(III) was oxidized. Arsenic was effectively adsorbed on iron (hydr)oxides as the consumption of oxalate and the increase of pH value. For the actual soil washing effluent, about 94.9% of total arsenic was removed after 120 min's treatment without pH adjustment. It has been demonstrated that As(V) was the dominant arsenic speciation adsorbed on iron (hydr)oxides. This study provides a promising alternative for remediation of arsenic contaminated soil in view of its low cost and environmental benign.

La recuperación de nutrientes por medio de la precipitación química a partir de agua residual, es un campo de investigación en el cual se debe indagar con el fin de desarrollar procesos más eficientes que permitan el aprovechamiento de compuestos a base de nitrógeno y fósforo aplicables a procesos agrícolas e industriales, logrando así una gestión integral más sostenible; en este sentido, este trabajo de grado estuvo orientado a ampliar el conocimiento y las experiencias en el tratamiento de agua residual mediante la caracterización estructural de los lodos obtenidos durante el proceso de precipitación química como alternativa de recuperación de nutrientes. El proyecto tuvo una etapa experimental a escala laboratorio en la cual se evaluaron la influencia de la dosis del reactivo precipitante sobre las características estructurales de obtenidos de un proceso de recuperación de nutrientes utilizando cloruro de magnesio (MgCl2) e hidróxido de sodio (NaOH) como reactivos de precipitación, y la influencia del tiempo de retención hidráulico (TRH) sobre las características del mismo. Los análisis de microscopia óptica y de SEM-EDS evidenciaron que al incrementar la dosis de MgCl2 como reactivo para la precipitación, se alcanzó una mayor formación de microcristales en su mayoría de forma cúbica, y de partículas de diferentes tamaños con una estructura amorfa, que de acuerdo con los resultados de la difracción de rayos X estuvo asociada a la presencia de sales como la estruvita e hidroxiapatita. Para los ensayos con NaOH como reactivo de precipitación se encontró que se promovió la precipitación de sales con estructuras amorfas, asociadas principalmente a la hidroxiapatita; así mismo se observó que el incremento del pH aunque favoreció los procesos de precipitación, no se reflejó en un incremento en el tamaño de las partículas formadas. En cuanto a la influencia del TRH sobre las características estructurales de las partículas obtenidas, el análisis la microscopia óptica y en contraste con las observaciones de SEM-EDS mostró que el incremento del TRH promovió la formación de partículas con una morfología más definida, tanto para las estructuras cristalinas como las amorfas The recovery of nutrients through chemical precipitation from wastewater, is a research field in which it is necessary to investigate in order to develop more efficient processes that allow the use of nitrogen and phosphorus-based compounds applicable to processes agricultural and industrial, thus achieving a more sustainable integral management; In this sense, this grade work was aimed at expanding knowledge and experiences in the treatment of wastewater through the structural characterization of sludge obtained during the chemical precipitation process as an alternative for nutrient recovery. The project had an experimental stage on a laboratory scale in which the influence of the dose of the precipitating reagent on the structural characteristics of obtained from a nutrient recovery process was evaluated using magnesium chloride (MgCl2) and sodium hydroxide (NaOH) as precipitation reagents, and the influence of hydraulic retention time (HRT) on its characteristics. The analysis of optical microscopy and SEM-EDS showed that by increasing the dose of MgCl2 as a reagent for precipitation, a greater formation of microcrystals was achieved, mostly in a cubic form, and of particles of different sizes with an amorphous structure, which According to the results of X-ray diffraction, it was associated with the presence of salts such as struvite and hydroxyapatite. For tests with NaOH as a precipitation reagent, it was found that the precipitation of salts with amorphous structures was promoted, mainly associated with hydroxyapatite; It was also observed that the increase in pH, although it favored precipitation processes, was not reflected in an increase in the size of the particles formed. Regarding the influence of HRT on the structural characteristics of the particles obtained, the optical microscopy analysis and in contrast to the observations of SEM-EDS showed that the increase in HRT promoted the formation of particles with a more defined morphology, both for Crystal structures like amorphous Pasantía de investigación (Ingeniero Ambiental)-- Universidad Autónoma de Occidente, 2019 Pregrado Ingeniero(a) Ambiental

El calentamiento global resultante del uso de combustibles fósiles está presionando a los gobiernos para que formulen y adopten políticas energéticas dirigidas a diferentes sectores de la economía. Una de las medidas más significativas en esta dirección es la eficiencia energética industrial, tema que concierne a las PYMES. Se identificó una PYME en la región del Valle del Cauca que reconociera la necesidad tanto económica como ambiental de tener un sistema más eficiente, especialmente en el consumo de energía. La empresa que cumplía con los requisitos La Despensa Natural S.A.S, empresa panificadora cuyo principal producto es el pan integral; empresa a la cual durante su tiempo de funcionamiento no se le ha realizado un estudio del desempeño energético, lo cual conlleva a desconocer si realizan un uso adecuado de la energía ya sea eléctrica o en forma de calor, lo que puede provocar ineficiencias en sus procesos. Teniendo presente estos aspectos, en este trabajo de grado se implementó un proceso de auditoría energética en una empresa panificadora La Despensa Natural S.A.S, de acuerdo a los lineamientos de la norma ISO 50002; estructurando las etapas del proceso de auditoría, por medio de un diagrama de flujo; obteniendo y analizando el desempeño energético histórico y actual, lo cual permitió determinar que el consumo energético de la planta no está asociado a la producción; identificando diferentes oportunidades de mejora del desempeño energético para los equipos de mayor consumo y por ende mayor potencial de ahorro; evaluando estas oportunidades de mejoras, las cuales están enlazadas con el cambio de operación y mantenimiento; y generando recomendaciones que posibiliten la toma de decisiones correctas con respecto al consumo de energía y así disminuir costos de esta índole. Este trabajo fue realizado en el marco del Proyecto: Programa de Evaluación Industrial - PEVI que desarrollo la Universidad Autónoma de Occidente con el financiamiento de la UPME y la ONUDI The global warming resulting from the use of fossil fuels is putting pressure on governments to formulate and adopt energy policies aimed at different sectors of the economy. One of the most significant measures in this direction is industrial energy efficiency, a subject that concerns SMEs. An SME was identified in the Valle del Cauca region that recognized the economic and environmental need to have a more efficient system, especially in energy consumption. The company that met the requirements La Dispense Natural S.A.S, bread company whose main product is whole meal bread; a company to which during its time of operation has not been made a study of energy performance, which leads to ignore whether they make an adequate use of energy either electrical or in the form of heat, which can cause inefficiencies in their processes. Keeping these aspects in mind, in this degree work an energy audit process was implemented in the bakery company La Despensa Natural S.A.S, according to the guidelines of ISO 50002; structuring the stages of the audit process, using a flow diagram; obtaining and analyzing historical and current energy performance, which allowed determining that the energy consumption of the plant is not associated with production; identifying different opportunities for improving energy performance for equipment with higher consumption and therefore greater savings potential; evaluating these improvement opportunities, which are linked to the change of operation and maintenance; and generating recommendations that make it possible to make correct decisions regarding energy consumption and thus reduce costs of this nature. This work was carried out within the framework of the Project: Industrial Assessment Centers - IACs, developed by the Universidad Autónoma de Occidente with funding from UPME and UNIDO Pasantía institucional (Ingeniero Electricista)-- Universidad Autónoma de Occidente, 2019 Pregrado Ingeniero(a) Electricista

En este proyecto se evaluó el potencial de formación de hidroxiapatita a partir de agua residual, como estrategia para la reducción de los impactos generados por las descargas de agua residual sobre los ecosistemas acuáticos y terrestres y para la recuperación de nutrientes a partir del tratamiento de agua residual. El trabajo experimental se realizó utilizando el agua residual afluente (ARC) y efluente (ART) de la Planta de tratamiento de agua residual de la Universidad Autónoma de Occidente. Para definir los ensayos se realizó una caracterización del ARC y del ART dónde se establecieron que las condiciones operacionales que se debían garantizar para promover la formación y precipitación de hidroxiapatita debían considerar un valor del producto de solubilidad (pKso) entre 52,3 y 57,9 en un intervalo de pH de reacción entre 8,7 y 13,7 unidades para las características del ARC y un valor de pKso entre 46,9 y 52,2 en un intervalo de pH de reacción entre 8,4 y 11,9 unidades para el ART. Para evaluar los procesos de recuperación de nutrientes, se realizaron ensayos de precipitación química a escala laboratorio, utilizando un mezclador programable PB-900 Phipps and Bird, con jarras de 700 mL. Para cada tipo de agua residual se realizaron 2 tipos de ensayos, uno ajuste de pH de reacción y MgCl2 como reactivo de precipitación y otro con ajuste de pH de reacción para promover la precipitación. El análisis de la calidad del agua residual en estudio mostró que la cantidad de hidroxiapatita potencialmente recuperable es de 51,14 ± 28,92 g por m3 de ARC tratada y de 20,36 ± 13,92 g por m3 de ART tratada, esto considerando un máximo aprovechamiento del fosfato disponible en los dos tipos de agua residual. Los resultados del desempeño del proceso de precipitación tanto con ajuste de pH de reacción y MgCl2 como reactivo de precipitación y solo con ajuste de pH de reacción, mostraron que, en términos de reducción de material particulado, se presentaron eficiencias de reducción en intervalos entre 51,4 y 71,6% y entre 64,1 y 100% para los ensayos con ARC y entre 55,3 y 100% y entre 54,6 y 100% para los ensayos con ART, respectivamente, medidas como la reducción en términos de SST In this project, the potential for the hydroxyapatite formation from wastewater was evaluated as a strategy for reducing the impacts generated by wastewater discharges on aquatic and terrestrial ecosystems and for the recovery of nutrients from wastewater treatment. The experimental work was carried out using the tributary wastewater (ARC) and effluent (ART) of the Wastewater Treatment Plant of the Universidad Autónoma de Occidente. In defining the tests, a characterization of the ARC and ART was carried out where it was established that the operational conditions to be ensured to promote the formation and precipitation of hydroxyapatite should consider a solubility product (pKso) value between 52.3 and 57.9 in a reaction pH range between 8.7 and 13.7 units for ARC characteristics and a pKso value between 46.9 and 52.2 in a reaction pH range between 8.4 and 11.9 units for ART. To evaluate nutrient recovery processes, laboratory-scale chemical precipitation tests were performed using a PB-900 Phipps and Bird programmable mixer, with 700 mL jars. For each type of wastewater, 2 types of tests were performed, one reaction pH adjustment and MgCl2 as a precipitation reagent and another with reaction pH adjustment to promote precipitation. Analysis of wastewater quality in study showed that the amount of potentially recoverable is 51.14 ± 28.92 g per m3 of treated ARC and of 20.36 ± 13.92 g per m3 of treated ART, this considering maximum use of available phosphate in both types of wastewater. The results of the precipitation process performance with both reaction pH adjustment and MgCl2 as precipitation reagent and only with reaction pH adjustment, showed that in terms of particulate matter reduction, reduction efficiencies were presented in intervals between 51,4 and 71,6% and between 64,1 and 100% for ARC tests and between 55,3 and 100% and between 54,6 and 100% for ART tests, respectively, measures such as the reduction in terms of SST Pasantía de investigación (Ingeniero Ambiental)-- Universidad Autónoma de Occidente, 2019 Pregrado Ingeniero(a) Ambiental