Effect of Free Ammonia, Free Nitrous Acid, and Alkalinity on the Partial Nitrification of Pretreated Pig Slurry, Using an Alternating Oxic/Anoxic SBR

The effect of free ammonia (NH3 or FA), free nitrous acid (HNO2 or FNA), and total alkalinity (TA) on the performance of a partial nitrification (PN) sequencing batch reactor (SBR) treating anaerobically pretreated pig slurry was studied. The SBR was operated under alternating oxic/anoxic (O/A) conditions and was fed during anoxic phases.This strategy allowed using organic matter to partially remove nitrite (NO2−) and nitrate (NO3−) generated during oxic phases.The desired NH4+ to NO2− ratio of 1.3 g N/g N was obtained when an Ammonium Loading Rate (ALR) of 0.09 g NH4+-N/L⋅d was applied. The system was operated at a solid retention time (SRT) of 15–20 d and dissolved oxygen (DO) levels higher than 3 mg O2/L during the whole operational period. PN mainly occurred caused by the inhibitory effect of FNA on nitrite oxidizing bacteria (NOB). Once HNO2 concentration was negligible,NH4+ was fully oxidized to NO3− in spite of the presence of FA. The use of biomass acclimated to ammonium as inoculum avoided a possible effect of FA on NOB activity.This work was funded by the Chilean Government (CONICYT/FONDECYT 3140276, CONICYT/PAI/MEC 80140011, FDD-UPLA-CC18105, Patagonia Seed Project 210.310.055-1SP, CONICYT/FONDAP/15130015, and Red Doctoral REDOC.CTA, MINEDUC Grant UCO1202 at University of Concepción)S

Greenhouse Gases Emissions from Wastewater Treatment Plants: Minimization, Treatment, and Prevention

The operation of wastewater treatment plants results in direct emissions, from the biological processes, of greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as indirect emissions resulting from energy generation. In this study, three possible ways to reduce these emissions are discussed and analyzed: minimization through the change of operational conditions, treatment of the gaseous streams, and prevention by applying new configurations and processes to remove both organic matter and pollutants. In current WWTPs, to modify the operational conditions of existing units reveals itself as possibly the most economical way to decrease N2O and CO2 emissions without deterioration of effluent quality. Nowadays the treatment of the gaseous streams containing the GHG seems to be a not suitable option due to the high capital costs of systems involved to capture and clean them. The change of WWTP configuration by using microalgae or partial nitritation-Anammox processes to remove ammonia from wastewater, instead of conventional nitrification-denitrification processes, can significantly reduce the GHG emissions and the energy consumed. However, the area required in the case of microalgae systems and the current lack of information about stability of partial nitritation-Anammox processes operating in the main stream of the WWTP are factors to be consideredThis work was supported by FONDECYT 1150285 (Chile) and Postdoctoral FONDECYT 3140276 (Chile) and by the Spanish Government through FISHPOL (CTQ2014-55021-R) and GRANDSEA (CTM2014-55397-JIN) projects cofunded by FEDER. The authors A. Pedrouso, A. Val del Río and A. Mosquera-Corral belong to the Galician Competitive Research Group GRC 2013-032, program cofunded by FEDERS

Effect of free ammonia nitrogen on the methanogenic activity of swine wastewater

Swine wastewater is characterized by high organic matter content, solids, nitrogen (expressed as total ammonia and protein) and heavy metals. This work determines the methanogenic toxicity effect of free ammonia contained in swine wastewater comparing raw swine wastewater (RW) and the liquid fraction of swine wastewater (TW). The values of IC50 (50% of inhibition) obtained for methanogenic bacteria ranged between 56 and 84% for RW, meanwhile IC50 for TW was ranged between 84 and 94%. Such inhibitory effects can be related to the free ammonia nitrogen concentration (> 40 mg NH3-N/L) contained in swine wastewater

Polyhydroxyalkanoates (PHAs) Production: A Feasible Economic Option for the Treatment of Sewage Sludge in Municipal Wastewater Treatment Plants?

Sludge is a by-product of municipal wastewater treatment plants (WWTPs) and its management contributes significantly to the operating costs. Large WWTPs usually have anaerobic sludge digesters to valorize sludge as methane and to reduce its mass. However, the low methane market price opens the possibility for generating other high value-added products from the organic matter in sludge, such as polyhydroxyalkanoates (PHAs). In this work, the economic feasibility of retrofitting two types of WWTPs to convert them into biofactories of crude PHAs was studied. Two cases were analyzed: (a) a large WWTP with anaerobic sludge digestion; and (b) a small WWTP where sludge is only dewatered. In a two-stage PHA-production system (biomass enrichment plus PHAs accumulation), the minimum PHAs cost would be 1.26 and 2.26 US$/kg PHA-crude for the large and small WWTPs, respectively. In a single-stage process, where a fraction of the secondary sludge (25%) is directly used to accumulate PHAs, the production costs would decrease by around 15.9% (small WWTPs) and 19.0% (large WWTPs), since capital costs associated with bioreactors decrease. Sensitivity analysis showed that the PHA/COD (Chemical Oxygen Demand) yield is the most crucial parameter affecting the production costs. The energy, methane, and sludge management prices also have an essential effect on the production costs, and their effect depends on the WWTP’s sizeThis research was funded by the Chilean Government through the Projects FONDECYT 1200850 and CRHIAM Centre grant number ANID/FONDAP/15130015. This research was also supported by the Spanish Government (AEI) through the TREASURE project (CTQ2017-83225-C2-1-R). Authors from USC belong to the Galician Competitive Research Group ED431C 2017/29. All these programs are co-funded by FEDER (EU)S

Assessment of a fast method to predict the biochemical methane potential based on biodegradable COD obtained by fractionation respirometric tests

The biochemical methane potential test (BMP) is the most common analytical technique to predict the performance of anaerobic digesters. However, this assay is time-consuming (from 20 to over than 100 days) and consequently impractical when it is necessary to obtain a quick result. Several methods are available for faster BMP prediction but, unfortunately, there is still a lack of a clear alternative. Current aerobic tests underestimate the BMP of substrates since they only detect the easily biodegradable COD. In this context, the potential of COD fractionation respirometric assays, which allow the determination of the particulate slowly biodegradable fraction, was evaluated here as an alternative to early predict the BMP of substrates. Seven different origin waste streams were tested and the anaerobically biodegraded organic matter (CODmet) was compared with the different COD fractions. When considering adapted microorganisms, the appropriate operational conditions and the required biodegradation time, the differences between the CODmet, determined through BMP tests, and the biodegradable COD (CODb) obtained by respirometry, were not significant (CODmet (57.8026 ± 21.2875) and CODb (55.6491 ± 21.3417), t (5) = 0.189, p = 0.853). Therefore, results suggest that the BMP of a substrate might be early predicted from its CODb in only few hours. This methodology was validated by the performance of an inter-laboratory studyconsidering four additional substratesThis research was supported by the Spanish Government (AEI) through the TREASURE project [CTQ 2017-83225-C2-1-R]. Moreover, authors would like to thank the EU and the AEI for funding, in the frame of the collaborative international Consortium AquaVal project, [PCIN-2017-047], financed under the ERA-NET WaterWorks2015 Co-funded Call. This ERA-NET is an integral part of the 2016 Joint Activities developed by the Water Challenges for a Changing World Joint Programme Initiative (Water JPI). Authors from the USC belong to the Galician Competitive Research Group GRC ED431C 2017/29. All these programs are co-funded by the FEDER (EU). Lucia Argiz is a Xunta de Galicia Fellow, Axudas de Apoio á Etapa Predoutoral (ED481A-2019/083), grant cofounded by the operative program FSE Galicia 2014–2020. In addition, this work was funded by the Chilean Government through the projects FONDECYT 1180650 and ANID/FONDAP/15130015. Marisol Belmonte belongs to LABMAI-Facultad de Ingeniería, HUB-Ambiental UPLA and UPLAguas Research GroupS

Nitrogen and Phosphorus Recovery From Anaerobically Pretreated Agro-Food Wastes: A Review

Anaerobic digestion (AD) is commonly used for the stabilization of agro-food wastes and recovery of energy as methane. Since AD removes organic C but not nutrients (N and P), additional processes to remove them are usually applied to meet the stringent effluent criteria. However, in the past years, there was a shift from the removal to the recovery of nutrients as a result of increasing concerns regarding limited natural resources and the importance given to the sustainable treatment technologies. Recovering N and P from anaerobically pretreated agro-food wastes as easily transportable and marketable products has gained increasing importance to meet both regulatory requirements and increase revenue. For this reason, this review paper gives a critical comparison of the available and emerging technologies for N and P recovery from AD residues

De “la perla del Paraná” a “el verde más cercano” : las representaciones acerca del crecimiento del turismo en la ciudad de San Pedro

Desde hace un tiempo en San Pedro, el turismo, el turista y todo lo relacionado con esta actividad se ha vuelto un tema de discusión, debate, análisis de café, notas periodísticas en medios locales; en fin, un sinnúmero de discursos y de voces hablan y comentan acerca del turismo. Nuevos emprendimientos hoteleros, cabañas, bungalows, campings históricos y modernos, dan una base material y aparentemente visible de que el turismo crece y mucho. Los emprendimientos turísticos y la llegada de visitantes a la ciudad crece año a tras año, se ejecutan obras de infraestructura local bajo la premisa de una mejor oferta turística, San Pedro se promociona como una ciudad para visitar, para conocer y hacer turismo, ya sea a través de medios electrónicos o tradicionales (páginas de Internet, prensa escrita, folletería, servicios de asistencia e información turística).\n La finalidad del presente trabajo es realizar un análisis del impacto que este desarrollo turístico ha tenido en los esquemas de percepción de sus habitantes, en las representaciones que construyen acerca de su ciudad, de sí mismos y de los turistas.\n El análisis se realizará enmarcado en el campo de las Ciencias de la Comunicación, y tomaremos de esta disciplina las herramientas analíticas necesarias que permitan profundizar en los discursos de actores sociales involucrados y en las representaciones que éstos construyen acerca de un fenómeno social que no es exclusivo de esta localidad bonaerense sino que se ha convertido en un tema de agenda mundial: el crecimiento del turismo.Fil: Acevedo, Marisol. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Buenos Aires, ArgentinaFil: Belmonte, Karina. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Buenos Aires, Argentin

Reverse Osmosis Concentrate: Physicochemical Characteristics, Environmental Impact, and Technologies

This study’s aim is to generate a complete profile of reverse osmosis concentrate (ROC), including physicochemical characteristics, environmental impact, and technologies for ROC treatment, alongside element recovery with potential valorization. A systematic literature review was used to compile and analyze scientific information about ROC, and systematic identification and evaluation of the data/evidence in the articles were conducted using the methodological principles of grounded data theory. The literature analysis revealed that two actions are imperative: (1) countries should impose strict regulations to avoid the contamination of receiving water bodies and (2) desalination plants should apply circular economies. Currently, synergizing conventional and emerging technologies is the most efficient method to mitigate the environmental impact of desalination processes. However, constructed wetlands are an emerging technology that promise to be a viable multi-benefit solution, as they can provide simultaneous treatment of nutrients, metals, and trace organic contaminants at a relatively low cost, and are socially accepted; therefore, they are a sustainable solution