Mitigation of hazards and risks of emerging pollutants through innovative treatment techniques of post methanated distillery effluent - A review

Distillery wastewater has high biological and chemical oxygen demand and requires additional treatment before it can be safely discharged into receiving water. It is usually processed through a biomethanation digester and the end product is the post-methanated distillery effluent (PMDE). Research have shown that PMDE released by molasses-based distilleries is a hazardous effluent that can cause harm to the biota and the environment; it contains elevated amount of total dissolved solids (TDS), total suspended solids (TSS) and excess levels of persistent organic compounds (POPs), heavy metals, phenolic compounds, and salts. The practice of wastewater reuse for irrigation in many water scarce countries necessitates the proper treatment of PMDE before it is discharged into receiving water. Convention methods have been in practice for decades, but innovative technologies are needed to enhance the efficiency of PMDE treatment. Advance physical treatment such as membrane separation technology using graphene, ion-exchange and ultrafiltration membranes; chemical treatment such as advanced oxidation methods, electrocoagulation and photocatalytic technologies; biological treatment such as microbial and enzymatic treatment; and hybrid treatment such as microbial-fuel cell (MFC), genetically modified organisms (GMO) and constructed wetland technologies, are promising new methods to improve the quality of PMDE. This review provides insight into current accomplishments evaluates their suitability and discusses future developments in the detoxification of PMDE. The consolidated knowledge will help to develop a better management for the safe disposal and the reuse of PMDE wastewater

Potential methane production and molecular characterization of bacterial and archaeal communities in a horizontal subsurface flow constructed wetland under cold and warm seasons

Organic matter removal in a horizontal subsurface flow constructed wetland (HSSF) treating wastewater is associated with the presence of bacteria and archaea. These organisms perform anaerobic microbial processes such as methanogenesis, which can lead to methane emissions. The aim of this study was to evaluate methane production and characterize the bacterial and archaeal communities found in HSSFs treating secondary urban wastewater during cold and warm seasons. The pilot system used in this study corresponds to four HSSFs, two planted with Phragmites australis (HSSF-Phr) and two planted with Schoenoplectus californicus (HSSF-Sch), the monitoring was carried out for 1335¿days. Removal efficiencies for organic matter (biological and chemical oxygen demand) and total and volatile suspended solids were evaluated in each HSSF. Moreover, biomass from each HSSF was sampled during warm and cold season, and methane productions determined by Specific Methanogenic Activity assays(maximum) (SMAm). In the same samples, the quantification and identification of bacteria and archaea were performed. The results showed that the degradation of organic matter (53–67% BOD5 and 51–62% COD) and suspended solids (85–93%) was not influenced by seasonal conditions or plant species. Potential methane production from HSSF-Sch was between 20 and 51% higher than from HSSF-Phr. Moreover, potential methane production during warm season was 3.4–42% higher than during cold season. The quantification of microorganisms in HSSFs, determined greater development of bacteria (38%) and archaea (50–57%) during the warm season. In addition, the species Schoenoplectus californicus has a larger number of bacteria (4–48%) and archaea (34–43%) than Phragmites australis. The identification of microorganisms evidenced the sequences associated with bacteria belong mainly to Firmicutes (42%), Proteobacteria (33%) and Bacteroidetes (25%). The archaea were represented primarily by Methanosarcinales, specifically Methanosaeta (75%) and Methanosarcina (16%). The community structure of the methanogenic archaea in HSSFs did not change throughout the seasons or plant species.Peer ReviewedPostprint (author's final draft

Bioremediation for Tanning Industry: A Future Perspective for Zero Emission

Bioremediation is one of the recent technological advancements for treating heavy metals containing industrial wastes. Leather industry utilizes almost 90% of chromium-based tanning agent for converting raw skins/hides into leather. Apart from chromium, metals such as aluminum, titanium, iron, and zirconium are widely used for various end applications. Hence, effluent after tanning processes contains higher concentration of heavy metals. Though Cr(III) is less toxic than Cr(VI), there is higher possibility of oxidation during subsequent treatment processes. Therefore, several methodologies have been developed to remove the heavy metals from the effluent before processing it for common effluent treatment. Phytoremediation is one of the eco-friendly techniques to remove the heavy metals from soil and wastewater. It is commonly used to remediate the unfertilized lands to fertile lands for agriculture. Moreover, metal absorbed plants are used for various applications such as tanning and preservative agent in the leather industry. Hence, metal absorbed plants are not dumped as solid waste. Similarly, algae and fungi are used to remove the heavy metals from the tannery waste and can be as metal-polysaccharide auxiliary chemicals during post-tanning processes. Utilization of nonpathogenic bacteria is also used for the absorption of heavy metals. In this case, the handling of biomass is easier compared to other methodologies owing to less time duration and labor friendly, whereas, in the case of phytoremediation, absorption rate directly depends on the growth duration. In the present chapter, detailed case study is carried out to compare the advantages and disadvantages of various bioremediation technologies employed for treating leather wastewater

Exploring METland® technology: treating wastewater by integrating electromicrobiology into Nature-based Solutions

El agua, además de ser fuente de vida, es un factor indispensable para un desarrollo social, económico y medioambiental. Actualmente, el uso global de agua se ha multiplicado por seis en los últimos 100 años, y continúa aumentando. Lo que antes era un bien de primera necesidad accesible a la mayoría de la población, ahora ha llegado a cotizar en bolsa (Nasdaq Veles California Water Index) para poder comprar el derecho a usarlo en el futuro. Una de las medidas urgentes que se han adoptado a nivel mundial está recogida en la Agenda 2030 de las Naciones Unidas. En ella se establecen los Objetivos de Desarrollo Sostenible, entre los que se encuentra el “garantizar la disponibilidad de agua y su ordenación y saneamiento sostenible”. Es en este contexto donde las Soluciones basadas en la Naturaleza (NBS, por sus siglas en inglés) pueden aportar una alternativa para el tratamiento de aguas residuales. Los humedales construidos constituyen un tipo de NBS basados en la creación de unas condiciones óptimas para el desarrollo de bacterias capaces de eliminar los contaminantes del agua. Además, cuentan con una vegetación específica que aporta soporte físico y biogeoquímico de la comunidad microbiana, lo que permite que sea un ecosistema muy resiliente. La electroquímica microbiana es una disciplina emergente que estudia la interacción entre microorganismos y materiales conductores de la electricidad. Su vertiente más aplicada está representada por las Tecnologías Electroquímicas Microbianas (METs, por sus siglas en inglés). Estos sistemas aprovechan el mecanismo de transferencia extracelular (EET) que presentan las bacterias electroactivas para convertir la energía química, almacenada en los contaminantes del agua, en corriente eléctrica. Una de las METs con mayor impacto ambiental son los METland®. El término nace de la incorporación de las METs a los humedales (wetlands) construidos con el objetivo de intensificar esta tecnología; es decir, aumentar la eficiencia de tratamiento de contaminantes del agua residual por unidad de superficie. El lecho de los METland® es de material carbonoso conductor de la electricidad, lo que permite que las bacterias electroactivas, como Geobacter, lo utilicen como aceptor terminal de electrones (TEA) extracelular. Esta fuente inagotable de TEA estimula el metabolismo oxidativo de las bacterias, incrementando la oxidación de contaminantes Esta tesis ha explorado la denominada tecnología METland®, operándola siempre en condiciones de anegación, donde los procesos anaerobios cobran más importancia. Los METland® han mejorado la eficiencia en el tratamiento de las aguas residuales con respecto a los humedales construidos, pero aún es necesario determinar cómo actúan e interaccionan entre sí, cada uno de sus principales componentes: vegetación, microorganismos y material del lecho (Capítulo 2). El impacto de la vegetación en la eficiencia del tratamiento de un METland® es menor que en un humedal construido ya que, el propio material conductor actúa como TEA sustituyendo, de una forma más efectiva, al oxígeno que producen las raíces de las plantas. En este nuevo nicho ecológico, las bacterias electroactivas encontrarán una ventaja competitiva, desarrollándose en mayor medida y dando lugar a “sinergias eléctroquímicas”. Los estudios electroquímicos (Capitulo 3) de la interfase bacteria-material, permiten explicar tanto la transferencia extracelular de electrones como el mecanismo de transferencia a través del lecho conductor. Los materiales con baja resistencia eléctrica, como el coque grafitado, favorecen una transferencia continua de electrones (mecanismo tipo geoconductor). En cambio, en otros como el biochar, abundan los compuestos oxigenados que, en forma quinonas, dan lugar una transferencia discontinua (mecanismo tipo geobatería). El flujo de electrones en un METland® anegado, además de estar determinado por el material del lecho, también va a depender de la concentración y localización del TEA. Este flujo de electrones puede ser controlado gracias a un nuevo dispositivo denominado e-sink (o sumidero de electrones), inventado y patentado por el grupo de investigación de Bioe (Capítulo 4). Gracias al efecto del e-sink, las reacciones de oxidación de la materia orgánica no se verán limitadas, lo que se traduce en un aumento de la eficiencia del tratamiento. El escalado de esta tecnología es ya una realidad, existen METlands localizados en diferentes regiones climáticas de todo el mundo. Estos sistemas pueden tratar cientos de metros cúbicos de agua al día de diversa naturaleza, tanto urbanas como industriales. En este contexto, hemos explorado su uso en el tratamiento de aguas residuales de ganadería. Los experimentos a escala laboratorio sugieren un futuro prometedor en su aplicación para el tratamiento de purines (Capítulo 5). Asimismo, el proceso de escalado del sistema METland se ha completado en un entorno real (TRL8) como el Instituto de Nutrición Animal de la Estación Experimental del Zaidín en Granada (CSIC). Como conclusión, la tecnología METland® es una realidad en el mercado del tratamiento de las aguas residuales de pequeñas aglomeraciones urbanas, dada su alta eficiencia y versatilidad. Los METlands son una solución respetuosa con el medio ambiente que minimiza los costes de operación y mantenimiento, que permite un tratamiento efectivo de las aguas residuales en localizaciones descentralizadas. No obstante, se debe seguir investigando en este campo para entender mejor la interacción bacteria–lecho conductor, así como seguir innovando en aquellos aspectos de diseño (configuración, materiales) que permitan optimizar su eficiencia

Bioprocessing for elimination antibiotics and hormones from swine wastewater

© 2017 Elsevier B.V. Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes’ removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater

Constructed Wetlands Process for Treating Sewage to Improve the Quantitative and Qualitative Management of Groundwater Resources

Water scarcity limits access to safe water for drinking and communities face some form of water stress, which can be related to insufficient supplies or inadequate infrastructures. Climate change plays a crucial role in water stress worldwide, as rising temperatures lead to more unpredictable weather and extreme weather events. In face of this challenge, the need to seek an alternative to protect groundwater resources and to decrease the use of public water is imposed. Sewage management seems to be a significant treatment of removing contaminants and undesirable components from polluted waters and safely return it to environment for irrigation and other uses. For this consideration, many treatment technologies are discussed in the literature including biological, physical and chemical processes. Among biological processes principally used for the treatment of sewage figured constructed wetlands. Constructed wetland system is considered as an economic, efficient and environmentally friendly sewage treatment method, based on adsorption and retention of pollutants by substrates, sorption by plants, and decomposition by microorganisms. Therefore, the chapter of this book throws will light on the principal mechanisms responsible to organic matter, nitrogen and phosphorus removal in different types of constructed wetlands, and provides recommendations concerning the factors affecting pollutants removal performance of constructed wetlands from sewage

Application of data mining techniques to predict the performance of matured Vertical Flow Constructed Wetlands Systems treating urban wastewater

The rapid urbanisation and industrialisation, due to technological advancement, led to severe environmental pollution. The environmental pollution in the last few decades resulted in an adverse impact on the environment causing massive accumulation of wastewater. Wastewater is one of the closest sources of environmental problems, at the same time water scarcity is becoming alarming due to its high demand as the global population is increasing. Hence, the application for managing available water resources becomes crucial. The ever-increasing demand for water brings the need for wastewater treatment as an alternative source of water. Constructed Wetlands (CW) have gained broader research attention due to their environmental and safety benefits for wastewater treatment. In this study, over three years of monitoring performance data from 03rd December 2014 to 28th March 2018 (thirty-nine months) of the vertical flow vertical wetlands system, receiving and treating domestic wastewater, were collected and utilised to assess and investigate the treatment performance efficiency of the Vertical Flow Constructed Wetland Systems (VFCWs) for removing pollutants from wastewater. Different laboratory-scale vertical-flow constructed wetlands filters filled with gravel and planted with common reed were built to remove removal from wastewater. The overall evaluation of the system treatment performance was calculated using percentage removal efficiency. The results were recorded it was observed that all vertical flow constructed wetland filters had recorded high removal performance for the water quality parameters, irrespective of filter set-up and operation. The system was discovered to be very useful in pollutants removal (water quality parameters) with significant efficiency. However, the high cost of analysis laboratory tests, time-consuming parameters couple with uncertainties associated with an analysis of water quality variables, lead to the development of two data mining technique models Multiple Linear Regressions (MLR) and Multilayer Perceptron (MLP). To predict the wastewater treatment performance of CW by predicting selected output water quality parameters these include Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), orthophosphate phosphorous (PO4-P), ammonium nitrogen (NH4-N) and suspended solids (SS) with respect to other known input parameters that will provide comfortable, reliable and cost-effective methods. Correlation analysis was conducted to select the most highly correlated input parameters to be used for the model development (prediction of output parameter). The monitoring dataset of all the parameters used was divided into training dataset to build prediction models (MLR and MLP) and testing dataset to validate the models constructed. In this current work, 70% of the whole data was used as a training dataset while the remaining 30% of the data set was used as a testing dataset. The prediction models built were evaluated and compared using two model evaluation criteria: graphical model evaluation (scatter plot and hydrograph) and numerical model error evaluation criteria using five model evaluation criteria, these include: Root Mean Square Error (RMSE), regression coefficient (r), Relative Absolute Error (RAE), mean absolute error (MAE) and root relative squared error (RRSE). The results obtained indicated that the predicted values of output parameters were in good agreement and relationship with their respective measured parameters. Thus, this showed that the two models built yielded satisfactory predictions and both models had performed reasonably well in predicting output variables concentrations accurately given the value of input dependent variable. Furthermore, the comparison between the model's outcomes showed that MLP model prediction performance was discovered to be better than the MLR model in a majority of water quality parameters. Both models built could be effectively used as a tool for predicting removal of water quality parameters efficiency of vertical flow constructed wetlands treating domestic wastewater and in predicting constructed wetland performance in wastewater treatment process in term of pollutants removal. The results demonstrated the potentiality of vertical flow constructed wetlands to treat domestic wastewater and remove pollutants for future reuse

Biodegradation of Chlorobenzenes at Oxic-anoxic Groundwater Interfaces: Assessing the Influences of Biogeochemical Interactions and Amendment Conditions

Chlorobenzenes (CBs) are persistent groundwater contaminants of concern at hundreds of industrial sites around the world. This work investigated microbial biodegradation of CBs at the interface between oxic and anoxic groundwater conditions as a potential strategy to remediate sites and minimize human exposure to contaminants. Biodegradation of micromolar concentrations (<60 µM) of 1,2,4-trichlorobenzene (1,2,4-TCB) was investigated in simulated oxic-anoxic interfaces (OAIs) using packed upflow columns. Increasing doses of model electron donor sodium lactate (NaLac) from 0.14 to 1.4 mM enhanced anaerobic reductive dechlorination activity, which stalled to monochlorobenzene without further dechlorination. However, excess NaLac (1.4 mM) suppressed aerobic CB degradation by increasing demand for limiting oxygen. Inclusion of wetland sediment within the column matrix was associated with enhanced reductive dechlorination and enrichment of anaerobic CB-dechlorinator Dehalobacter. Dechlorinated daughter products were not associated with enhanced aerobic degradation, suggesting no benefit of an initial reductive dechlorination step for 1,2,4-TCB mineralization. Biodegradation of 1,2,4-TCB at simulated OAIs was also tested under nitrate- and sulfate-reducing conditions, which are common in anaerobic groundwater plumes. Under constant electron donor (0.55 mM NaLac), increased nitrate and sulfate concentrations decreased reductive dechlorination activity. Complete inhibition was observed at 2.5 mM nitrate and 10 mM sulfate. Re-oxidation of reduced sulfur negatively impacted aerobic CB degradation. In contrast, nitrate enhanced aerobic CB degradation by serving as a sink for reduced compounds that compete with CB for limited concentrations of oxygen. Under excess nitrate (2.5 mM), a 270% increase in aerobic degradation was observed. In separate batch experiments, effects of granular activated carbon (GAC) amendment on aerobic CB biodegradation were investigated. GAC seeded with an aerobic enrichment culture was shown to effectively facilitate mineralization of 1,2-dichlorobenzene in synthetic media and in site water. Increased GAC dose (0.13-6.7 mg/L) decreased degradation activity while increased wetland sediment loads (0.33-333 g/L) increased degradation. Results highlighted potential tradeoffs between sorption and biodegradation. Overall, these findings emphasize the complex interactions between site and amendments at OAIs that warrant careful consideration in order to implement successful remediation strategies. Results from these studies demonstrate the potential for substantial CB bioremediation under optimal environmental conditions

Organic Waste Recycling

"This book covers the principles and practices of technologies for the control of pollution originating from organic wastes (e.g. human faeces and urine, wastewater, solid wastes, animal manure and agro-industrial wastes) and the recycling of these organic wastes into valuable products such as fertilizer, biofuels, algal and fish protein and irrigated crops. Each recycling technology is described with respect to: - Objectives - Benefits and limitations - Environmental requirements - Design criteria of the process - Use of the recycled products - Public health aspects. Organic Waste Recycling includes case studies, examples, exercises and questions. This book is intended as a text or reference book for third or fourth year undergraduate students interested in environmental science, engineering and management, and graduate students working in the environment-related disciplines. It also serves as a reference text for policy makers, planners and professionals working in the environment and sustainable development fields.