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- Removal of organic matter and nitrogen in an horizontal subsurface flow (HSSF) constructed wetland under transient loadsPublication . Albuquerque, Antonio; Arendacz, M.; Gajewska, M.; Obarska-Pempkowiak, Hanna; Randerson, Peter; Kowalik, P.A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1–8 to weeks 9–14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient load.
- Multi-criteria analysis for site selection for the reuse of reclaimed water and biosolidsPublication . Albuquerque, Antonio; Scalize, Paulo Sergio; Ferreira, Nilson Clementino; Silva, FloraLow pH soils with insufficient organic matter can benefit from the application of reclaimed water (RW) and biosolids. The presence of nutrients also aids plant growth. This paper presents the results of two integrated research studies, both carried out in the Beira Interior Region (Covilhã, Portugal); one used RW for irrigation, the other applied paper mill sludge to agricultural land. In both cases, multiple criteria based on GIS tools were used for site selection. In the first study, the characteristics of RW analyzed over 2 years were found suitable for crop irrigation. The RW had moderate organic content, low electrical conductivity (CE), high nutrient content (N, P), and low concentrations of nitrate, metals and phytotoxic elements (Al, B, Cl and Na). The multi-criteria analysis was carried out taking into account environmental, technical and economic criteria and a suitable area of 30.5 ha was found for RW irrigation. In the second work, the paper mill sludge was considered suitable for application to agricultural land. Its concentrations of N, P and heavy metals did not a present risk for soil contamination and were suitable for soil improvement and crop production. A multi-criteria analysis based on similar criteria was conducted and a suitable area of 253 ha was found for sludge application.
- Caracterização físico-química de cascas de amêndoas e nozes para valorização em obras de terraPublication . Marchiori, Leonardo; Nouioua, Thamer; Morais, Maria Vitoria; Silva, Flora Cristina Meireles; Albuquerque, Antonio; Andrade Pais, Luís; Cavaleiro, VictorOs resíduos agroindustriais têm sido investigados para aplicações de engenharia devido à sua elevada produção e ausência de valorização adequada face aos requisitos legais e de políticas e metas de sustentabilidade. O estudo das caraterísticas das cascas de amêndoas (CA) e nozes (CN) têm suscitado interesse na comunidade científica para desenvolver materiais alternativos e inovadores, com design sustentável, em várias aplicações. Este trabalho tem como objetivo caracterizar e analisar as propriedades físico-químicas de CA, CN e de um solo residual, bem como de duas misturas de cada resíduo com o solo, com 10% e 40% de cascas, para eventual aplicação em obras de terra. Os resultados mostraram que ambos os resíduos poderiam ser incorporados no solo para torná-los mais granulares e reduzir a densidade específica, além de terem potencial para remover alguns poluentes da água devido à presença de aluminosilicatos com K2O, CaO e SiO2. Esta aplicabilidade poderia reduzir a utilização de solos naturais em obras de terra, a incineração de ambas as cascas e sua deposição em aterros sanitários, podendo promover a sua valorização e criar produtos baseados em resíduos no âmbito da economia circular. No entanto, são necessários estudos adicionais para uma melhor compreensão do seu potencial para utilização em obras de terra, nomeadamente ensaios de lixiviação, degradação e adsorção.
- Recycling pulp mill sludge to improve soil fertility using GIS toolsPublication . Ribeiro, Paulo; Albuquerque, Antonio; Quinta-Nova, Luís; Cavaleiro, VictorPulp mill sludge produced in the Cova da Beira region (Portugal) contains organic matter (11-47%), nitrogen (38-2560 mg N/kg) and phosphorus (167-370 mg P/kg), which may be valuable for increasing soil productivity. The levels of heavy metals are below the limits recommended by legislation and the amount of nitrogen and phosphorous to be introduced in soils does not present a risk for nutrient leaching. After identifying the environmental and technical restrictions on its application, an area of 1650 ha was identified where the sludge can be applied in forage crops, fruit trees, olive groves and vineyards. A suitable area was also found for a biosolids storage centre. The use of GIS allowed to define a sludge application index and to produce land-use suitability maps, which can be useful for sludge management.
- Effect of vegetation on the performance of horizontal subsurface flow constructed wetlands with lightweight expanded clay aggregatesPublication . Mesquita, Maria da Conceição; Albuquerque, Antonio; Amaral, Leonor; Nogueira, ReginaThis research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m(-2) day(-1). The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.
- Analysis of constructed wetland performance for irrigation reusePublication . Monte, Helena Marecos do; Albuquerque, AntonioMost of the wastewater treatment systems in small rural communities of the Cova da Beira region (Portugal) consist of constructed wetlands (CW) with horizontal subsurface flow (HSSF). It is believed that those systems allow the compliance of discharge standards as well as the production of final effluents with suitability for reuse. Results obtained in a nine-month campaign in an HSSF bed pointed out that COD and TSS removal were lower than expected. A discrete sampling also showed that removal of TC, FC and HE was not enough to fulfill international irrigation goals. However, the bed had a very good response to variation of incoming nitrogen loads presenting high removal of nitrogen forms. A good correlation between mass load and mass removal rate was observed for BOD5, COD, TN, NH4-N, TP and TSS, which shows a satisfactory response of the bed to the variable incoming loads. The entrance of excessive loads of organic matter and solids contributed for the decrease of the effective volume for pollutant uptake and therefore, may have negatively influenced the treatment capability. Primary treatment should be improved in order to decrease the variation of incoming organic and solid loads and to improve the removal of COD, solids and pathogenic. The final effluent presented good physical–chemical quality to be reused for irrigation, which is the most likely application in the area.
- Toxicity reduction and biodegradability enhancement of cork processing wastewaters by ozonationPublication . Gomes, A.C.; Silva, Lúcia; Simões, Rogério; Canto, N.; Albuquerque, AntonioBiodegradability enhancement and detoxification of cork boiling wastewater (CBW) are required for the successful implementation of biological treatment options. We studied the possibility of achieving these goals through ozonation pre-treatment by experimenting on the effect of ozone dose and pH. The CBW used had a pH of 5.81, a chemical oxygen demand (COD) of 1,865 mg L-1, a biochemical oxygen demand (BOD5) of 498 mg L-1 and total phenol (TP) and tannin compounds concentrations of 523 and 399 mg L-1, respectively. The ozone doses ranged from 0.27 to 2.63 for the O-3(applied)/COD0 ratios with samples at natural pH and set to 3.33 and 9.96. Ozonation allowed the BOD20/COD ratio (biodegradability index) to increase from 0.37 to 0.63 and a toxicity reduction from 3.08 to 1.24 TU (Microtox). The corresponding removals obtained were 15.2-62.0%, 38.4-83.2% and 56.7-92.1% for COD, TP and colour, respectively. The best outcome of ozonation pre-treatment requires O-3(applied)/COD0 ratios over 1.5 and an acid pH. The increase of TP removals with ozone dose at acid pH led to biodegradability enhancement and CBW detoxification. However, for similar conditions the highest COD removals were obtained at alkaline pH due to the hydroxyl radicals' high oxidation ability but lack of selectivity.
- Analysis of the chemical properties of almond and walnut shells for use in earthworksPublication . Nouioua, Thamer; Marchiori, Leonardo; Albuquerque, Antonio; Silva, Flora Cristina Meireles; Pais, Luís Andrade; Cavaleiro, VictorAlmond (AS) and walnut shells (WS) have attracted the interest of scientific community due to the possibility of developing innovative eco-friendly materials. This work aims to analyze the chemical characteristics of AS, WS, a residual granitic soil (RGS) and two mix-tures of waste:soil (10:90% and 40:60%) for evaluating their compatibility for earthworks application. Results show that both wastes could be incorporated into RGS for improving its properties and additionally can remove some water pollutants due to the presence of K2O, CaO and SiO2. This application could reduce the need to use soil natural resources, incineration of both wastes or their deposition in sanitary landfills and can promote their valorization and even create value-added products in the scope of the circular economy. However, additional studies are needed for a better understanding of their potential for using in earthworks, namely leaching, solubilization and adsorption experiments.
- The influence of evapotranspiration on vertical flow subsurface constructed wetland performancePublication . Bialowiec, Andrzej; Albuquerque, Antonio; Randerson, PeterThis paper presents an example of the importance of evapotranspiration in constructed wetlands, with vertical subsurface flow, comparing different methods of treatment efficiency calculations and discussing the influence of evapotranspiration on removal rates. The application of reed, marked by high transpiration ability, is a cheap and effective method of landfill leachate disposal. A 2-year study examined the effectiveness of leachate treatment in constructed wetlands with reed. Two kinds of vertical subsurface flow systems: first with sand, and second with combined two layers of sewage sludge and sand has been tested. 1, 3, and 5 mmd(-1) hydraulic loading rates of landfill leachate have been applied. Daily evapotranspiration was in the range from 0.98 to 2.99 mmd(-1) in the first year of research and from 2.56 to 4.61 mmd(-1) in the second year. The influence of evapotranspiration rate on chemical oxygen demand (COD) removal rate was examined. Two methods of removal efficiency calculation have been used: first based on inlet and outlet COD concentrations, second on mass balance determination. Research showed that the removal efficiency calculated as a comparison between initial and final concentration is significantly lower, than expected from mass balance, especially, when higher hydraulic loading rates were applied.
- Biodegradability enhancement and detoxification of cork processing wastewater molecular size fractions by ozonePublication . Santos, Diana C.; Silva, Lúcia; Albuquerque, Antonio; Simões, Rogério; Gomes, A.C.Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration membranes and five fractions were obtained: four retentates (>100, 50-100, 20-50 and 10-20 kDa) and one permeate (<10 kDa); which were used to study the correlation of molecular size with biodegradability and toxicity before and after ozonation. The results show that molecular size is correlated with organic load and restrains biodegradability. The fraction with >100 kDa corresponds to 56% of the organic load and the one with <10 kDa only 8%. The biodegradability of fractions increased 182% with fractions molecular size reduction from >100 to < 10 kDa and the chemical oxygen demand (COD) was from 3436 to 386 mg L-1. For biodegradability enhancement the best outcome of ozonation was obtained with compounds having molecular size >20 kDa and range from 5% up to 175% for applied ozone doses to COD ratios between 0.15 and 0.38.