Abstract This work aimed to analyze the wastewater treatment in Chile, as example of developing country, for discussing the participation and development of Constructed Wetlands (CW), addressing the current situation besides technical and regulatory challenges that allow increasing in their application, and water reuse of their effluents in irrigation activities. For this, official reports, scientific and regulatory information were discussed and analyzed. The results showed that Chile has a treatment coverage of 100% in urban areas. However, in rural areas the coverage is below 20%. Although there more than 800 WWTP, the CW have a minority participation below 2%, and CW were used only in decentralized WWTP as secondary treatment. CW were competitive in construction and operation cost. Likewise, experimental CW showed similar depurative performance than activated sludge systems. This would make to CW an attractive technology for descentralized WWTP. For this, WWTP proposals based on CW were analyzed, and new treatment sequences were also developed and discussed by area, but there are challenges to overcome. This challenges were discussed in this paper. Finally, wastewater reuse requires further research, as well as a specific regulatory framework. Furthermore, important definitions in legal and incentives issues are required. These points would be similar to other developing countries.

Resumen Este trabajo tuvo por objetivo analizar el tratamiento de aguas servidas para Chile, como ejemplo de país en vía de desarrollo, discutiendo sobre la participación y desarrollo de los humedales construidos (HC), abordando la realidad actual, junto a los desafíos técnicos y normativos, que permitan un aumento de su aplicación, y la reutilización de efluentes en riego de actividades agrícolas. Para esto, se realiza una discusión y análisis de reportes oficiales, bibliografía y normativa. Los resultados mostraron que Chile tiene una cobertura de tratamiento de 100% en zonas urbanas. Sin embargo, para las áreas rurales, la cobertura alcanza como máximo 20%. Pese a que existen más de 800 PTAS, los HC tienen una participación minoritaria, inferior a 2%, utilizados sólo en PTAS descentralizadas de la zona centro como tratamiento secundario. Los HC instalados fueron competitivos en costos de construcción y operación. Así, HC experimentales mostraron un desempeño depurativo similar al de sistemas de lodos activados. Esto haría a los HC una tecnología atractiva de implementar en PTAS descentralizadas. Para esto, se analizaron propuestas de PTAS basadas en HC; también se realizaron propuestas de secuencias de tratamiento por zona geográfica, pero existen desafíos por vencer y que se discuten en este artículo. Finalmente, la reutilización de efluentes demanda de más estudio e investigación, así como de un marco regulatorio específico. Además, se necesita la definición de temas jurídicos y de incentivos. Estos puntos serían similares a otros de países en vías de desarrollo.

Background Anaerobic digestion is a technology applied successfully to converting organic matter into biogas. However, the presence of inhibitory compounds such as antibiotics can adversely affect methane production. The aim of this study is to evaluate the toxic effect of chlortetracycline hydrochloride (CLOR) on the methanogenic bacteria. In order to study the methanogenic toxicity of CLOR, different concentrations of CLOR (10, 50, 100, 200 mg L- 1) were evaluated by methanogenic toxicity assays using three feedings. Results Maximum methane production was obtained for the assays with 10 mg CLOR L- 1, the values obtained were 277 ± 4.07; 193 ± 11.31 and 166 ± 7.07 mL for the first, second and third feedings, respectively. The average values for acetic, propionic and butyric acid at start of the experiments were 2104 ± 139; 632 ± 7.6; 544 ± 26 mg L- 1, respectively. The VFA values obtained finally of the experiment were dependent on the evaluated antibiotic concentrations, indicating that the efficiency of methanogenesis is directly affected by the CLOR concentration. Conclusions CLOR is an effective methanogenic bacteria inhibitor. Moreover, the results show that CLOR has a bactericidal effect on methanogenic activity given that methane production did not recover during the third feeding. This study shows that the 50% inhibitory concentration (IC50) for methanogenic bacteria in 10 mg L- 1.

Farm slurry management from storage and/or treatment is the main source of odors from swine production, which are determined by factors such as operational variations (organic loading), cleaning of facilities and animal diet (pH) or environmental conditions (temperature). The aim of this study was to evaluate the influence of pH, temperature and organic loading on odor generation during anaerobic digestion of swine slurry. The methodology employed batch experimental units under controlled pH (6.0, 6.5, 7.0 and 8.0) and temperature (20, 35 and 55 °C) conditions. Additionally, an Upflow Anaerobic Sludge Blanket (UASB) system was operated under two Organic Loading Rate (OLR) conditions as Chemical Oxygen Demand (COD) (Phase I: 0.4 g L-1 d-1 of COD, Phase II: 1.1 g L-1 d-1 of COD). Odor (batch and UASB reactor) was evaluated by detection and recognition threshold as Dilution Threshold (D-T). Acidic conditions (pH 6.0) and thermophilic temperatures (55 °C) increased odors (1,358 D-T) and acidified the system (Intermediate/Total Alkalinity ratio (IT/TA): 0.85) in batch experiments. Increasing OLR on UASB reactor reduced odors from 6.3 to 9.6 D-T d-1 due to an increase in the production of biogas (0.4 to 0.6 g g-1 COD removed of biogas).

Las plantas de tratamiento de aguas servidas basadas en humedales construidos de flujo horizontal subsuperficial (HSS), logran su etapa de madurez después de dos años de operación. La eficiencia de operación de los sistemas depende de la estacionalidad, tipo de plantas y periodo de madurez del sistema. El objetivo de este trabajo es evaluar la influencia de la estación y de las especies Phragmites australis y Schoenoplectus californicus, en la eficiencia de depuración en materia orgánica y nutrientes de unidades de HSS, durante la etapa operativa de puesta en marcha. Con esta finalidad, se implementaron cuatro unidades de HSS bajo condiciones climáticas mediterráneas australes. Dos unidades fueron plantadas con Phragmites australis y las otras dos, con Schoenoplectus californicus. En este trabajo se presentan los resultados de la etapa de puesta en marcha, que cubre los primeros 193 días de operación. Se evaluó la influencia de la especie de planta y la estación (invierno y primavera), en la eficiencia de depuración de materia orgánica (Demanda Biológica de Oxígeno, DBO5, y Demanda Química de Oxígeno, DQO) y nutrientes (nitrógeno (N-NH4+, N-NO3- y NT) y fósforo (P-PO4-3 y PT)). Las unidades de HSS plantadas con Phragmites australis mostraron mejor adaptación temprana que las unidades de HSS plantadas con Schoenoplectus californicus. Sin embargo, las eficiencias de eliminación fueron similares en todas las unidades. Estacionalmente, se pudo evidenciar una diferencia de eliminación para DQO (invierno: 18 a 30%, primavera: 45 a 55%) y NT (invierno: 25 a 65%, primavera: 25 a 35%)

The Wastewater Treatment Plant (WWTP) based on horizontal subsurface flow constructed wetland (HSS) achieved its full operation after two years of implantation. Removal efficiency of this WWTP is function of seasonality, type of species plant and maturity period of the system. The objective of this work is evaluating of the influence of season and plant species Phragmites australis and Schoenoplectus californicus in removal of organic matter and nutrients in HSS units during start up operation phase. To this end, four HSS units were implemented in Mediterranean Austral weather conditions. Two HSS units were planted with Phragmites australis, and the other two HSS units were planted with Schoenoplectus californicus. This paper shows results from start up operation phase which cover the first 193 days. It was evaluated the influence of plant species and season (winter and spring), in the removal efficiency of organic matter (5-day Biological Oxygen Demand, BOD5, and Chemical Oxygen Demand, COD) and nutrients (nitrogen (NH4+-N, NO3- -N and TN) and phosphorus (PO4-3-P and TP)). The HSS units planted with Phragmites australis showed better early adaptation than HSS units planted with Schoenoplectus californicus. However, removal efficiencies were similar in all units. Seasonality, it can evidence differences for COD (winter: 18 to 30%, spring: 45 to 55%) and TN (winter: 25 to 65%, spring: 25 to 35%).

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.

Water flows provided by irrigation systems may be associated with dissolved organic carbon (DOC) content in the soil solution and may modify the mobility of pesticides, such as chlorpyrifos (CHP). These compounds were analyzed under field conditions, evaluating their distribution in the soil profile under excessive irrigation in a Humic Haploxerand soil. The trial was carried out in soil columns located under the canopy of apple trees (Malus domestica Borkh.) in an orchard located in the Bío-Bío Region, Chile. The insecticide CHP was applied 120 g hL-1, and later the natural run off was collected from the foliage to the columns. Surface irrigation was used as a control, the equivalent to 4 L h-1 weekly, plus two treatments over the columns of 6 and 8 L h-1 per pulse, respectively. Samples were obtained at three column depths: 0-5, 5-20 and 20-30 cm. The results showed that in spite of the fact there was no interaction between depth and irrigation, a greater concentration of CHP was observed in the samples with greater water flow, with significant differences between the treatments at a depth of 20-30 cm, which suggests some level of influence on vertical mobility. DOC shows stratification with greater concentrations at the surface and lower concentrations at depth, with significant differences between the superficial stratum (0-5 cm) and the lower strata (5-20, 20-30 cm). These results are discussed in relation to explaining the movement of CHP in the soil profile.

Los flujos de agua aportados por los sistemas de riego pueden estar asociados al contenido de carbono orgánico disuelto (DOC) en la solución del suelo y modificar la movilidad de pesticidas como el clorpirifos (CHP). Se analizan estos compuestos bajo condiciones de campo, evaluando su distribución en el perfil de suelo ante un exceso de riego en un suelo Humic Haploxerands. El ensayo se desarrolló en columnas de suelo ubicadas bajo la canopia de un huerto de manzanos (Malus domestica Borkh.) ubicado en la Región del Bío-Bío, Chile. Se aplicaron 120 g hL-1 del insecticida CHP, posteriormente se recogió el escurrimiento natural desde el follaje hacia las columnas. Se aplicó riego tendido como control, equivalente a 4 L h-1semanal, más dos tratamientos sobre las columnas de 6 y 8 L h-1 por pulso, respectivamente. Se obtuvieron muestras a tres alturas de columna 0-5, 5-20 y 20-30 cm. Los resultados muestran que a pesar que no existe interacción entre profundidad y riego, se observa una mayor concentración de CHP en las muestras con mayor flujo de agua, con diferencias significativas entre los tratamientos a la profundidad de 20-30 cm, lo que sugiere algún nivel de influencia en su movilidad vertical. El DOC muestra una estratificación de mayor a menor concentración desde la superficie hacia la profundidad, con diferencias significativas entre la estrata superficial (0-5 cm) y las inferiores (5-20, 20-30 cm). Estos resultados se discuten en relación a explicar la movilidad del CHP en el perfil del suelo.

Kraft mill effluent, due to its organic matter content and acute toxicity, must be treated. A primary treatment followed by a secondary treatment is the most common system. Aerated lagoon is also considered an effective biological treatment, although this technology has some drawbacks related with operation parameters and land extension space. Moreover, the recovery efficiency for micropollutants contained in kraft mill effluent is questioned due to the anoxic zone in the system. The goal of this work is to evaluate the performance of the aerated lagoon to remove stigmasterol contained in kraft mill effluents. Kraft mill effluent was treated by an aerated lagoon (AL), which was operated with three different stigmasterol load rates (SLR = 0.2, 0.6 and 1.1 mg/L x d) and a hydraulic retention time of 1 day. The AL’s maximum Chemical Oxygen Demand (COD) removal was 65%, whereas the Biological Oxygen Demand (BOD5) was around 95%. The removal efficiency of stigmasterol removal was 96% when SLR 1.1 mg/L x d, although an accumulation of stigmasterol was detected for lower SLR.

The present study had the purpose of testing through supervised trials the variability of Chlorpyrifos (CHP) residues associated to a sampling methodology validated in the field, on applying the active ingredient (AI) in an apple orchard, with two different spraying methodologies and at different periods of vegetative development. The persistence on applying 1.8 kg ha-1 (Lorsban 50%WP®, Dow AgroScience, USA), using a knapsack sprayer with engine (KSE) and a high volume sprayer (HVS) was studied. The model that had the best fit for the diminution of the residues was appraised through linear regression. The results show high coefficients of variation (CV) with both application methods, KSE (69%) and HVS (43%). The sampling variability of apples contributes to 99.3% with KSE and 97.7% with HVS. The sample results show an initial rapid diminution of CHP, with a half-life for apples, leaves and soil of 5.0, 2.3 and 4.5 days for KSE and 8.3, 2.7 and 11.2 days for HVS, respectively. The adjusted declination model for each substrate does not permit modeling the degradation of CHP residues through a simple model.

El presente estudio tiene por objetivo probar mediante ensayos supervisados la variabilidad de los residuos de clorpirifos (CHP) asociados a una metodología de muestreo validada en terreno, al aplicar el ingrediente activo (IA) en huerto de manzanos, con dos diferentes metodologías de aspersión y en épocas diferentes de desarrollo vegetativo. Se estudió la persistencia al aplicar 1,8 kg ha -1(Lorsban 50%WP®, Dow AgroScience, USA), mediante nebulizadora con bomba de espalda con motor (NBEM) y con nebulizadora de alto volumen (NAV). Se evaluó el modelo que representa el mejor ajuste de la declinación de los residuos a través de regresión no lineal. Los resultados muestran altos coeficientes de variación (CV) en ambos métodos de aplicación, NBEM (69%) y NAV (43%). La variabilidad del muestreo de manzanas contribuye con un 99.3% con NBEM y 97.7% con NAV. Los resultados muestran una disminución inicial rápida del CHP, con una vida media para manzanas, hojas y suelo de 5,0; 2,3 y 4,5 días para NBEM y de 8,3; 2,7 y 11,2 días para NAV, respectivamente. El modelo de declinación ajustado para cada sustrato no permite modelar la degradación de los residuos de CHP a través de un modelo simple.

En el proceso productivo del salmón se eliminan residuos líquidos y sólidos. Si estos residuos no son tratados o retirados de los sitios de cultivos pueden ser tóxicos a los sistemas acuáticos, debido a su descomposición y producción de amonio (NH4+) y nitrito (NO2-). En los ecosistemas acuáticos las bacterias nitrificantes son responsables de la oxidación de estos compuestos. El objetivo del presente trabajo es obtener cultivos de bacterias amonio oxidantes (BAO) y nitrito oxidantes (BNO) en sistemas de tipo batch y evaluar la capacidad de eliminación de nitrógeno, determinando las respectivas cinéticas. Como inóculo inicial se utilizó sedimentos de un centro de cultivo de salmones. Los resultados muestran la baja actividad nitrificante presente en los sedimentos, obteniéndose para BAO producciones de 197-206mg·l-1 N-NO2-, velocidades de consumo de O2 (VCO) con respecto del factor estequiométrico de 0,023mg·l-1·min-1 N y consumo neto de O2 (CNO) de 0,055mg·l-1·min-1 O2, mientras que para BNO, se obtuvieron producciones de 404-631mg·l-1 N-NO3-, VCO de 0,027mg·l-1·min-1 N y CNO de 0,0122mg·l-1·min-1 O2. Los resultados corroboran la incapacidad de las bacterias nitrificantes de oxidar la gran cantidad de compuestos nitrogenados generados por esta actividad acuícola

Solid and effluent wastes are generated by salmon productive process. Wastes can produce toxic effects to the aquatic system due to the ammonia (NH4+) and nitrite (NO2-) production, if they are discharged without any treatment. In the aquatic ecosystems nitrifying bacteria are responsible for the nitrogen oxidize compounds. The goal of this work is to obtain Oxidize Ammonia Bacteria (OAB) and Oxidize Nitrite Bacteria (ONB) in batch assays and also, to evaluate the nitrogen removal and kinetic, respectively. The batch assays inoculations were done with sediments from salmon culture. Results show a lower sediment nitrifying capacity. The OAB values were between 197-206mg·l-1 N-NO2- whereas Oxygen Uptake Rate (OUR) respect to stoichiometric factor and the Oxygen Consumption Net (OCN) were 0.023mg·l-1·min-1 N and 0.055mg·l-1·min-1 O2. On the other hand, ONB values were between 404-631mg·l-1 N-NO3-, whereas 0.027 mg·l-1·min-1 N, and 0.0122mg·l-1·min-1 O2 were determine for OUR and OCN, respectively. Due to the high concentration of the nitrogen compounds bacteria are not able to oxidize nitrogen generation from wastes

No processo produtivo do salmão se eliminam resíduos líquidos e sólidos. Se estes resíduos não são tratados ou retirados dos lugares de cultivos podem ser tóxicos aos sistemas aquáticos, devido a sua decomposição e produção de amônio (NH4+) e nitrito (NO2-). Nos ecossistemas aquáticos as bactérias nitrificantes são responsáveis da oxidação destes compostos. O objetivo do presente trabalho é obter cultivos de bactérias amônio-oxidantes (BAO) e nitrito-oxidantes (BNO) em sistemas do tipo batch e avaliar a capacidade de eliminação de nitrogênio, determinando as respectivas cinéticas. Como inóculo inicial se utilizou sedimento de um centro de cultivo de salmões. Os resultados mostram a baixa atividade nitrificante presente nos sedimentos, obtendo-se para BAO produções de 197-206mg·l-1 N-NO2-, velocidades de consumo de O2 (VCO) em relação ao fator estequiométrico de 0,023mg·l-1·min-1 N e consumo neto de O2 (CNO) de 0,055mg·l-1·min-1 O2, enquanto que para BNO, se obtiveram produções de 404-631mg·l-1 N-NO3-, VCO de 0,027mg·l-1·min-1 N e CNO de 0,0122mg·l-1·min-1 O2. Os resultados destacam a incapacidade das bactérias nitrificantes de oxidar grande quantidade de compostos nitrogenados gerados por esta atividade aqüícola

Kraft mills are responsible for the massive discharge of highly polluted effluents, and new bleaching processes (i.e. Total Chlorine Free (TCF)) is presented as a feasible option to reduce this environmental impact. However, increased TCF pulp production is accompanied by an increase in chelate use. The most commonly used chelates, ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DPTA), are considered to be relatively persistent substances in water treatment plants, and consequently environmentally critical compounds. The purpose of this work is to investigate DPTA behaviour in an anaerobic system. An Anaerobic Filter (AF) was operated with three different DPTA load rates (LR DPTA = 0.07 - 0.28 gDPTA/L×d), and the operating strategy was to maintain the anaerobic system stable during the entire operation (alkalinity ratio below 0.3). The AF's maximum Chemical Oxygen Demand (COD) removal was 59%, whereas the Biological Oxygen Demand (BOD5) was around 95%. However, only 5% of DPTA removal was observed under anaerobic conditions during the first operating period. Scanning electronic microscopy indicates that the operating system reduced microorganism biodiversity

Efluentes industriais altamente coloridos são difíceis de degradar utilizando as tecnologias fisico-químicas e bacterianas existentes atualmente. O sistema enzimático extracelular secretado pelo fungo de podridão branca apresenta um grande potencial oxidativo, capaz de dar início a decomposição das estruturas residuais dos compostos responsáveis pela cor destes efluentes. Aspectos fisiológicos foram avaliados para optimizar as condições de descoloramento de um corante sintético, Poly R-478, pelo fungo de podridão branca Trametes versicolor # 52J. Os experimentos de descoloramento foram realizados em operação semi-contínua durante três ciclos para melhorar a eficiência do processo. As melhores eficiências de descoloramento (65 % a 80%) foram obtidas em culturas de fungos tratadas em condições limitadas de nitrogênio em atmosfera de ar.

Physiological aspects were evaluated to determine optimal conditions for the decolorization of a synthetic dye, Poly R-478, by white-rot fungus Trametes versicolor # 52J. The decolorization experiments were carried out in semicontinuous operation during three cycles to improve the process efficiency. The best decolorization efficiencies (65% to 80%) were obtained in fungal cultures performed in nitrogen limited conditions under aerobic conditions.

A biodegradabilidade aerobica das águas residuais provenientes de diferentes procesos de branqueos de pulpa kraft foi estudada. Os efluentes são gerados no branqueo com cloro ou parcialmente sustituido com dioxido de cloro (CB) ou bem em processos livres do cloro (TCF). A biodegradabilidade, quantificada como DQO foi maior para as águas do processo CB. Tendo em conta o elevado conteúdo orgânico do efluente CB obteinse uma maior concentraç&ão do DQO final neste efluente comparado com o efluente TCF. Uma fracçao recalcitrante maior a 43,000 Da no effluente BC foi encontrada, isto significa um tratamento adicional específico para sua eliminaçã o. A toxicidade foi totalmente eliminada despois do tratamento aeração.

Aerobic biodegradability of effluents from different Eucalyptus kraft pulp bleaching processes was studied. Bleaching effluents were obtained from: i) Chlorine Bleaching (CB) processes, with partial substitution of chlorine by chlorine dioxide and ii) Total Chlorine Free (TCF) processes. The overall biodegradability, in terms of Chemical Oxygen Demand (COD) was higher for TCF effluents (96-98%) than for CB ones (82-93%). Taking into account the higher organic load of CB effluents, this fact implied a much higher residual COD for them (100-180 mg/L) than for TCF effluents (10-30 mg/L). Furthermore, a refractory fraction of molecular weight higher than 43,000 Da was found in CB effluent, which implied the necessity of a further specific treatment. The toxicity was completely removed after the biological treatment