Grass species with potential for rangelands restoration in northern Mexico: an assessment with environmental niche modeling.

Environmental niche modeling (ENM) has emerged as a promising tool for identifying grass species with potential for rangeland restoration. This approach can detect suitable areas and environments where these species can be planted. In this study, we employed ENM to estimate the potential distribution range of 50 grass species of the grasslands and shrublands of northern Mexico. The outcome of the ENM served to identify grass species with potential for restoration in Mexico, especially those not commonly used for that purpose in the past. Results suggested the possibility of selecting seven grass species with the potential for revegetating degraded grasslands, nine for shrublands, and six for alkaline soils. This research provides insights into the environmental adaptations of different grass species distributed in the rangelands of northern Mexico. Ecologists, conservation planners, researchers, and range managers could use these outcomes and the maps of the potential distribution ranges as supportive information to conduct effective restoration efforts. In turn, this can assist in increasing the probability of success of future rangelands restoration programs, which are often costly in terms of financial investments and labor.

Environmental Niche Dynamics of Blue Grama (Bouteloua gracilis) Ecotypes in Northern Mexico: Genetic Structure and Implications for Restoration Management.

Understanding the genetic structure adopted by natural populations and its relation to environmental adaptation is critical for the success of restoration programs. We evaluated the genetic structure and temporal environmental niche dynamics of blue grama (Bouteloua gracilis) in 48 populations. The genetic evaluation was performed through amplified fragment length polymorphism (AFLP) molecular markers. The maximum entropy method was used to model the past, present, and future environmental niches of the three clusters derived from the genetic analysis. The environmental niches of the three genetic clusters showed dynamic overlaps and isolations during the last interglacial and glacial maximum. The paleoclimatic events, which occurred during those periods, may have reinforced genetic exchange among populations and affected their genetic structure. Genetic clusters also presented different environmental niches in the present. Thus, they can be considered as three distinct ecotypes and restoration programs must be carried out using local germplasm from each environmental niche to increase their chance of success. Based on the environmental niches of the genetic clusters, changes are expected in the near and mid-century future. Therefore, climate change must be considered for species conservation management and future restoration programs.

The Impact of Treated Wastewater Irrigation on the Metabolism of Barley Grown in Arid and Semi-Arid Regions.

The use of treated wastewater (TWW) for irrigation has gained global attention since it reduces pressure on groundwater (GW) and surface water. This study aimed to evaluate the effect of TWW on agronomic, photosynthetic, stomatal, and nutritional characteristics of barley plants. The experiment with barley was established on two bands: one band was irrigated with GW and the other with TWW. The evaluation was performed 25, 40, 60, 90, and 115 days after sowing (DAS). Results showed that irrigation with TWW increased (p < 0.01) grain yield by 54.3% and forage yield by 39.4% compared to GW irrigation. In addition, it increased plant height (PH) (p = 0.013), chlorophyll concentration index (CCI) (p = 0.006), and leaf area index (LAI) (p = 0.002). TWW also produced a positive effect (p < 0.05) in all the photosynthetic efficiency parameters evaluated. Barley plants irrigated with TWW had lower stomatal density (SD) and area (SA) (p < 0.001) than plants irrigated with GW. Plants irrigated with TWW had a higher P concentration (p < 0.05) in stems and roots and K concentration in leaves than plants irrigated with GW. We concluded that the use of TWW induced important biochemical, physiological, and agronomic changes in barley plants. Hence, the use of TWW may be a sustainable alternative for barley production in arid and semi-arid regions. This study was part of a government project, which aimed to develop a new metropolitan irrigation district with TWW. This study may contribute to the sustainability of water resources and agricultural practices in northern Mexico.

Impact of Cations (Na+, K+, Mg+2) and Anions (F-, Cl-, SO42-) Leaching from Filters Packed with Natural Zeolite and Ferric Nanoparticles for Wastewater Treatment.

Natural zeolites have been employed to adsorb contaminants in water. This study is aimed to evaluate the cation and anion leaching from the zeolite after the wastewater was passed through filters packed with a natural zeolite (heulandite-CaAl2Si7O18·6H2O). Eight treatments were evaluated in a 2 × 2 × 2 factorial treatment design. Factor A was the zeolite with two levels: 127 g and 80.4 g. Factor B was the nanoparticles with two levels: one bag (3.19 g) and two bags (6.39 g); and Factor C was the use of a magnet: with and without. There were two replications; hence, a total of 16 filters were employed. The water was obtained from a municipal wastewater treatment plant (MWTP). The cations (Na+, K+; Mg+2 and Ca+2) and anions (F-, Cl- and SO42-) were measured before (influent = IW) and after filtering (effluent = EW) three times. All treatments leached the cations Na+ (EW in a range of 175 to 232 ppm), K+ (EW in a range of 15.4 to 33.2 ppm), and Mg+2 (EW in a range of 7.40 to 10.8 ppm) but did not leach Ca+2. Likewise, the treatments leached the anions F- (EW in a range of 7.59 to 8.87 ppm), Cl- (EW in a range of 85.9 to 120 ppm), and SO42- (EW in a range of 139 to 146 ppm). We conclude that this natural zeolite leaches cations (except Ca+2) and anions in MWTP passed through filters. Therefore, its application in wastewater treatment should be considered for purposes such as agriculture and animal production and not for drinking water.

Association between Postmortem Kidney Biopsy Findings and Acute Kidney Injury from Patients with SARS-CoV-2 (COVID-19).

BACKGROUND AND OBJECTIVES: AKI in coronavirus disease 2019 (COVID-19) is associated with higher morbidity and mortality. The objective of this study was to identify the kidney histopathologic characteristics of deceased patients with diagnosis of COVID-19 and evaluate the association between biopsy findings and clinical variables, including AKI severity. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Our multicenter, observational study of deceased patients with COVID-19 in three third-level centers in Mexico City evaluated postmortem kidney biopsy by light and electron microscopy analysis in all cases. Descriptive and association statistics were performed between the clinical and histologic variables. RESULTS: A total of 85 patients were included. Median age was 57 (49-66) years, 69% were men, body mass index was 29 (26-35) kg/m2, 51% had history of diabetes, 46% had history of hypertension, 98% received anticoagulation, 66% were on steroids, and 35% received at least one potential nephrotoxic medication. Severe AKI was present in 54% of patients. Biopsy findings included FSGS in 29%, diabetic nephropathy in 27%, and arteriosclerosis in 81%. Acute tubular injury grades 2-3 were observed in 49%. Histopathologic characteristics were not associated with severe AKI; however, pigment casts on the biopsy were associated with significantly lower probability of kidney function recovery (odds ratio, 0.07; 95% confidence interval, 0.01 to 0.77). The use of aminoglycosides/colistin, levels of C-reactive protein and serum albumin, previous use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, antivirals, nonsteroid anti-inflammatory drugs, and anticoagulants were associated with specific histopathologic findings. CONCLUSIONS: A high prevalence of chronic comorbidities was found on kidney biopsies. Nonrecovery from severe AKI was associated with the presence of pigmented casts. Inflammatory markers and medications were associated with specific histopathologic findings in patients dying from COVID-19.

La salud de las personas adultas mayores durante la pandemia de COVID-19 / The health of older adults during the COVID-19 pandemic

La pandemia por COVID-19 representa un problema para la salud pública, más aún, al tener un alto grado de mortalidad en las personas adultas mayores. Para garantizar el cuidado de este grupo poblacional, se hace un análisis de las necesidades y medidas preventivas diseñadas para la prevención y control de la enfermedad causada por el virus SARS-Cov2. OBJETIVO: Analizar la situación de las personas adultas mayores ante la problemática del nuevo coronavirus y compilar las principales medidas de prevención general y especifica para la protección de este grupo vulnerable. METODOLOGÍA: Se realizó una revisión sistemática de artículos indexados, en PubMed, LATINDEX, Redalyc, Scielo, Scopus, Dialnet y Google Scholar y en fuentes oficiales nacionales e internacionales. Se utilizó para la búsqueda las siguientes palabras clave: COVID-19, SARS-Cov2, adulto mayor, medidas preventivas coronavirus, pandemia. RESULTADOS: De 9 artículos consultados y de las fuentes oficiales mencionadas, se analizó los principales ejes en relación a la situación económica y laboral, la salud, así como los factores de riesgo generales para la población y específicos para las personas adultas mayores. Los principales factores de riesgo hallados son la edad avanzada, las comorbilidades presentes en este grupo poblacional, los padecimientos demenciales, además de factores sociales como la discriminación por edad y los estereotipos en relación a la dependencia y fragilidad de las personas mayores. La prevención del COVID-19 en adultos mayores debe incluir además de la contención y cuidados específicos, la atención psicosocial. CONCLUSIONES: Los adultos mayores conforman el grupo de mayor impacto negativo por el SARS-Cov2, COVID-19, su vulnerabilidad ante esta pandemia proviene no solo de su edad, sino por la situación económica, laboral y enfermedades asociadas a su edad, su soledad le confiere mayor riesgo ya que tiene que salir a buscar sus víveres, de no apoyarles el impacto en su salud será indudablemente negativo

The COVID-19 pandemic represents a public health problem, even more so, since it has a high degree of mortality in older adults. To guarantee the care of this population group, an analysis was made of the needs and preventive measures designed for the prevention and control of the disease caused by the SARS-Cov2 virus. AIM: Analyze the situation of older adults facing the problem of the new coronavirus and compile the main general and specific prevention measures for the protection of this vulnerable group. METHODOLOGY: A systematic review of indexed articles was carried out in PubMed, LATINDEX, Redalyc, Scielo, Scopus, Dialnet and Google Scholar and in official national and international sources. The following keywords were used for the search: COVID-19, SARS-Cov2, elderly, preventive measures, coronavirus, pandemic. RESULTS: From 9 articles consulted and from the aforementioned official sources, the main axes were analyzed in relation to the economic and labor situation, health, as well as the general risk factors for the population and specific for the elderly. The main risk factors found are advanced age, comorbidities present in this population group, dementing illnesses, as well as social factors such as age discrimination and stereotypes regarding the dependency and frailty of older people. Prevention of COVID-19 in older adults should include psychosocial care in addition to specific containment and care. CONCLUSIONS: Older adults make up the group with the greatest negative impact due to SARS-Cov2, COVID-19, their vulnerability to this pandemic comes not only from their age, but also due to the economic, work situation and diseases associated with their age, their loneliness gives them greater risk since you have to go out to look for your food, if you do not support them the impact on your health will undoubtedly be negative

Furosemide stress test and interstitial fibrosis in kidney biopsies in chronic kidney disease.

BACKGROUND: Interstitial fibrosis (IF) on kidney biopsy is one of the most potent risk factors for kidney disease progression. The furosemide stress test (FST) is a validated tool that predicts the severity of acute kidney injury (especially at 2 h) in critically ill patients. Since furosemide is secreted through the kidney tubules, the response to FST represents the tubular secretory capacity. To our knowledge there is no data on the correlation between functional tubular capacity assessed by the FST with IF on kidney biopsies from patients with chronic kidney disease (CKD). The aim of this study was to determine the association between urine output (UO), Furosemide Excreted Mass (FEM) and IF on kidney biopsies after a FST. METHODS: This study included 84 patients who underwent kidney biopsy for clinical indications and a FST. The percentage of fibrosis was determined by morphometry technique and reviewed by a nephropathologist. All patients underwent a FST prior to the biopsy. Urine volume and urinary sodium were measured in addition to urine concentrations of furosemide at different times (2, 4 and 6 h). We used an established equation to determine the FEM. Values were expressed as mean, standard deviation or percentage and Pearson Correlation. RESULTS: The mean age of the participants was 38 years and 44% were male. The prevalence of diabetes mellitus, hypertension and diuretic use was significantly higher with more advanced degree of fibrosis. Nephrotic syndrome and acute kidney graft dysfunction were the most frequent indications for biopsy. eGFR was inversely related to the degree of fibrosis. Subjects with the highest degree of fibrosis (grade 3) showed a significant lower UO at first hour of the FST when compared to lower degrees of fibrosis (p = 0.015). Likewise, the total UO and the FEM was progressively lower with higher degrees of fibrosis. An inversely linear correlation between FEM and the degree of fibrosis (r = - 0.245, p = 0.02) was observed. CONCLUSIONS: Our findings indicate that interstitial fibrosis correlates with total urine output and FEM. Further studies are needed to determine if UO and FST could be a non-invasive tool to evaluate interstitial fibrosis. TRIAL REGISTRATION: ClinicalTrials.gov NCT02417883.

Psychometric properties of the resilience scale in Mexican patients with chronic hemodialysis / Propiedades psicométricas de la escala de medición de resiliencia en pacientes mexicanos con hemodiálisis crónica

Abstract Introduction Resilience consists of a series personalized skills to cope with adverse situations and overcome them, and even emerge strengthened. Resilience in patients with chronic renal insufficiency (CRI) treated with hemodialysis (HD) has been evaluated with general questionnaires that are not specific for this population. Objective To evaluate the psychometric properties of a resilience questionnaire in patients treated with chronic HD. Method The study included 280 patients with CRI (aged 18 to 85, 44% women) treated with HD for at least two months in six hemodialysis units in Mexico, who completed Beck's depression and anxiety inventories, an inventory of cognitive distortions, and the Mexican Resilience Measurement Scale (RESI-M). Results Owing to the duplication of more than one factor, two of the 43 items were eliminated in the exploratory factor analysis. We confirmed five factors that explained 63.4% of the total variance, with a Cronbach's alpha of .96 (the alpha ranges in the five factors from .85 to .95). The confirmatory analysis showed a theoretical structural model that fits the empirical data in an acceptable, balanced, and parsimonious way. The five factors correlate positively with each other and negatively with anxiety and depression symptoms and distorted thoughts. Discussion and conclusion The RESI-M scale is valid and reliable for assessing resilience in patients treated with chronic HD. Resilience factors evaluated with RESI-M are a potential therapeutic target to reduce depression and anxiety symptoms in these patients.

Resumen Introducción La resiliencia consiste en una serie de habilidades personalizadas que sirven para afrontar situaciones adversas y superarlas, e incluso salir fortalecido. La resiliencia en pacientes con insuficiencia renal crónica (IRC) tratados con hemodiálisis (HD) se ha evaluado con cuestionarios generales, no específicos para esta población. Objetivo Evaluar las propiedades psicométricas de un cuestionario de resiliencia en pacientes tratados con HD crónica. Método Se incluyeron 280 pacientes con IRC (edad 18 a 85 años, 44% mujeres) tratados con HD al menos dos meses en seis unidades de hemodiálisis en México, que respondieron los inventarios de depresión y ansiedad de Beck, un inventario de distorsiones cognitivas y la escala de medición de resiliencia con mexicanos (RESI-M). Resultados Por duplicidad en más de un factor, se eliminaron dos de 43 reactivos en el análisis factorial exploratorio. Se confirmaron cinco factores que explicaron 63.4% de la varianza total, con alfa de Cronbach de .96 (el alfa en los cinco factores va de .85 a .95). El análisis confirmatorio mostró un modelo estructural teórico que se ajusta aceptable, equilibrada y parsimoniosamente a los datos empíricos. Los cinco factores se correlacionan positivamente entre ellos y negativamente con los síntomas de ansiedad, depresión y los pensamientos distorsionados. Discusión y conclusión La escala RESI-M es válida y confiable para evaluar resiliencia en pacientes tratados con HD crónica. Los factores de resiliencia evaluados con la RESI-M son un blanco terapéutico potencial para disminuir los síntomas depresivos y ansiosos en estos pacientes.

Assessing the Committed Effective Dose From 226Ra in Thermal Spring Water From San Diego De Alcala, Chihuahua, Mexico.

The oral administration of mineral-rich spring water is known as hydropinic treatment and is used to treat certain ailments. Health benefits are attributed to thermal spring water containing radioactive elements such as radium; this has popularized use of such radioactive water in various parts of the world, causing those who ingest it to increase their internal radiation dose. The goal of this study was to assess the activity concentrations of Ra present in the thermal spring waters of San Diego de Alcala, in the state of Chihuahua, Mexico, and to estimate the health risk posed to patients by the effective dose received from ingesting this water during hydropinic treatments. Water samples were taken from different areas of the San Diego de Alcala thermal springs, and pH, temperature, electrical conductivity, and total dissolved solids were measured. The Ra activity concentrations were measured with a liquid scintillation counter. The activity concentrations of Ra in sampled water varied from 125 to 452 mBq L with an average of 276 ± 40 mBq L. The committed effective dose from each of the Ra activity concentrations found in samples ranged from 9.80 × 10 to 4.0 × 10 mSv for hydropinic treatments being carried out in San Diego de Alcala thermal spring spas. Different treatments had different intake rates (200, 600, 1,000, and 1,500 mL d) and occurred over periods of 2 or 3 wk. According to the guidelines of the US Environmental Protection Agency, the maximum permissible amount of radium in drinking water is 185 mBq L; the Ra content in most of the collected samples exceeded this limit. The committed effective doses varied with Ra concentration and intake rate; none exceeded the World Health Organization's reference dose for drinking water of 0.1 mSv y, which is the maximum amount to which the population should be exposed.

Removing Organic Matter and Nutrients from Pig Farm Wastewater with a Constructed Wetland System.

Pollutants from pig farms in Mexico have caused problems in many surface water reservoirs. Growing concern has driven the search for low-cost wastewater treatment solutions. The objective of this research was to evaluate the potential of an in-series constructed wetland to remove nutrients from wastewater from a pig farm. The wetland system had a horizontal flow that consisted of three cells, the first a surface water wetland, the second a sedimentation cell, and the third a subsurface flow wetland. The vegetation used was Thypa sp. and Scirpus sp. A mix of soil with red volcanic rock (10⁻30 mm diameter) and yellow sand (2⁻8 mm diameter) was used as a substrate for the vegetation. The experiments were carried out in duplicate. Water samples were collected at the inflow and outflow of the cells. Two hydraulic retention times (HRT) (5 and 10 days) and three treatments were evaluated: 400, 800, and 1200 mg·L−1 of chemical oxygen demand (COD) concentration. Data was collected in situ for temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). COD, total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3⁻N), and total phosphorous (TP) were analyzed in the laboratory. The results showed that the in-series constructed wetland is a feasible system for nutrient pollutant removal, with COD removal efficiency of 76% and 80% mg·L−1 for a 5- and 10-day HRT, respectively. The removal efficiency for TKN, NH3⁻N, and TP reached about 70% with a 5-day HRT, while a removal of 85% was obtained with a 10-day HRT. The wetland reached the maximum removal efficiency with a 10-day HRT and an inflow load of 400 mg·L−1 of organic matter. The results indicate that HRT positively affects removal efficiency of COD and TDS. On the other hand, the HRT was not the determining factor for TP removal. Treatment one, with an initial COD concentration of 400 mg·L−1, had the highest removal of the assessed pollutants, allowing for the use of water for irrigation according to Mexican regulatory standards (NOM-001). The water quality resulting from treatments two and three (T2 = 800 mg·L−1 of COD and T3 = 1200 mg·L−1 of COD) did not comply with minimal requirements for irrigation water.

Use of trace elements addition for anaerobic digestion of brewer's spent grains.

The brewery industry generates a large amount of by-products and notably Brewer's Spent Grain (BSG) which seems an attractive substrate for anaerobic digestion. Nevertheless, previous studies have shown risk of inhibition in the mono-digestion of lignocellulosic substrates. One way to stabilize the reaction is the addition of trace elements. The current study evaluates and compares the stability of BSG anaerobic mono-digestion with and without addition of trace elements for several BSG samples. Based on the average composition of the BSG, two levels of nutrients addition were defined and tested on 4 different BSG samples. Control reactors, without addition of nutrients, showed signs of instability after 3 months or less of operation, with a decrease in performance and even collapse. On the contrary, supplemented reactors led to a COD removal rate of 60-65% and a methane production ranged between 220 and 350 NL CH4.kg-1 VSadded, depending on the sample. According to these results, guidelines for nutrients solution addition adapted to BSG degradation were defined.

Indoor Radon Gas (222Rn) Levels in Homes in Aldama, Chihuahua, Mexico and the Risk of Lung Cancer.

Radon (222Rn) is an odorless and tasteless gas that is known to cause lung cancer. The objective of this research was to quantify the levels of exposure to radon among people living in an environment rich in uranium (U). Radon concentrations were measured for 3 days in 12 homes in Aldama, Mexico. Homeowners agreed to participate in the study; hence, the sample was non-probabilistic. Radon was measured with a portable AlphaGuard Radon Monitor (Genicron Instruments GmbH), which was placed in a bedroom of each home at a height of 0.74 m. Gas levels were registered in Becquerels (Bq m−3), with readings taken every 10 min along with readings of ambient temperature (AT), air pressure (AP), and relative humidity (RH). We found that radon gas levels in Aldama exceed the maximum permissible limits (USA: 148 Bq m−3). Levels were higher at night, and were above the maximum permissible level recommended by the International Atomic Energy Agency of the United Nations (<200 Bq m−3). Most residents in the area have family histories of lung problems, but it was difficult to establish a strong correlation between 222Rn and lung cancer. Federal, state, and municipal governments should take stronger action to reduce the effects of radon gas on communities.

Anaerobic digestion of Brewery Spent Grains: Trace elements addition requirement.

The current study evaluates and compares the stability of anaerobic digestion of Brewery Spent Grains (BSG) with and without addition of nutrients. Based on the composition of the BSG two levels of nutrients addition were defined. Control reactor, without addition of nutrients, showed signs of instability after 3months of operation and collapsed. On the contrary, supplemented reactors led to a COD removal rate of 60% and a methane production of 280NLCH4.kg-1 VSadded. According to these results, it was possible to define an additive solution adapted to BSG degradation.

Developing a Water Quality Index (WQI) for an Irrigation Dam.

Pollution levels have been increasing in water ecosystems worldwide. A water quality index (WQI) is an available tool to approximate the quality of water and facilitate the work of decision-makers by grouping and analyzing numerous parameters with a single numerical classification system. The objective of this study was to develop a WQI for a dam used for irrigation of about 5000 ha of agricultural land. The dam, La Vega, is located in Teuchitlan, Jalisco, Mexico. Seven sites were selected for water sampling and samples were collected in March, June, July, September, and December 2014 in an initial effort to develop a WQI for the dam. The WQI methodology, which was recommended by the Mexican National Water Commission (CNA), was used. The parameters employed to calculate the WQI were pH, electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS), total hardness (TH), alkalinity (Alk), total phosphorous (TP), Cl-, NO3, SO4, Ca, Mg, K, B, As, Cu, and Zn. No significant differences in WQI values were found among the seven sampling sites along the dam. However, seasonal differences in WQI were noted. In March and June, water quality was categorized as poor. By July and September, water quality was classified as medium to good. Quality then decreased, and by December water quality was classified as medium to poor. In conclusion, water treatment must be applied before waters from La Vega dam reservoir can be used for irrigation or other purposes. It is recommended that the water quality at La Vega dam is continually monitored for several years in order to confirm the findings of this short-term study.

Levels and Distribution of Pollutants in the Waters of an Aquatic Ecosystem in Northern Mexico.

The availability of good quality water resources is essential to ensure healthy crops and livestock. The objective of this study was to evaluate the level of pollution in Bustillos Lagoon in northern Mexico. Physical-chemical parameters like sodium, chloride, sulfate, electrical conductivity, nitrates, and the pesticide dichlorodiphenyltrichloroethane (DDT) were analyzed to determine the water quality available in the lagoon. Although DDT has been banned in several countries, it is still used for agricultural purposes in Mexico and its presence in this area had not been analyzed previously. Bustillos Lagoon was divided into three zones for the evaluation: (1) industrial; (2) communal lands; and (3) agricultural. The highest concentrations of sodium (2360 mg/L) and SAR (41 meq/L) reported in the industrial zone are values exceeding the United Nations Food and Agricultural Organization (FAO) irrigation water quality guidelines. DDT and its metabolites were detected in all of the 21 sites analyzed, in the agricultural zone ∑DDTs = 2804 ng/mL, this level is much higher than those reported for other water bodies in Mexico and around the world where DDT has been used heavily. The water in the communal zone is the least contaminated, but can only be recommended for irrigation of plants with high stress tolerance and not for crops.

Prediction of anaerobic biodegradability and bioaccessibility of municipal sludge by coupling sequential extractions with fluorescence spectroscopy: towards ADM1 variables characterization.

Advanced dynamic anaerobic digestion models, such as ADM1, require both detailed organic matter characterisation and intimate knowledge of the involved metabolic pathways. In the current study, a methodology for municipal sludge characterization is investigated to describe two key parameters: biodegradability and bioaccessibility of organic matter. The methodology is based on coupling sequential chemical extractions with 3D fluorescence spectroscopy. The use of increasingly strong solvents reveals different levels of organic matter accessibility and the spectroscopy measurement leads to a detailed characterisation of the organic matter. The results obtained from testing 52 municipal sludge samples (primary, secondary, digested and thermally treated) showed a successful correlation with sludge biodegradability and bioaccessibility. The two parameters, traditionally obtained through the biochemical methane potential (BMP) lab tests, are now obtain in only 5 days compared to the 30-60 days usually required. Experimental data, obtained from two different laboratory scale reactors, were used to validate the ADM1 model. The proposed approach showed a strong application potential for reactor design and advanced control of anaerobic digestion processes.

A statistical comparison of protein and carbohydrate characterisation methodology applied on sewage sludge samples.

Biochemical characterization of organic matter is becoming of key importance in wastewater treatment. The main objectives are to predict organic matter properties, such as granulation or flocculation, and hence treatment performance. Although standardized methods do exist for some organic molecules, such as volatile fatty acids or lipids, there are no standard methods to measure proteins and carbohydrates content, both biochemical families being the main components of sewage sludge. Consequently, the aim of the present work is to investigate the efficiency of several colorimetric methods to determine proteins and carbohydrates content as well as their compatibility with the sludge matrices. The different methods have been evaluated based on statistical criteria such as sensitivity, linearity, accuracy, rightness, and specificity using standard molecules such as Bovine Serum Albumin (BSA), glucose, cellulose and a certified reference product. The Lowry and the Dubois methods have been shown to be the best compromise for the considered criteria after having been tested on sewage sludge samples obtained from different locations in a wastewater treatment plant. In average, the measured volatile fatty acids, lipids, proteins and carbohydrates contents represented 80 ± 7% (% volatile solids) of the organic matter. Proteins and carbohydrates represented in average 69 ± 3%. This study underlined that the choice of a relevant methodology is of great importance for organic matter measurement.