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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.
- 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.
- Influence of bed media characteristics on ammonia and nitrate removal in shallow horizontal subsurface flow constructed wetlandsPublication . Albuquerque, Antonio; Oliveira, José; Semitela, Sabrina; Amaral, LeonorTwo bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4–N m−2 d−1 and 3 g NO3–N m−2 d−1) and removal efficiencies (>62% for ammonia, 90–100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrification–denitrification. The nitrogen loading rate of both ammonia (0.8–2.4 g NH4–N m−2 d−1) and nitrate (0.6–3.2 g NO3–N m−2 d−1) seem to have influenced the respective removal rates.
- Evaluation of the simultaneous removal of organic matter, nitrogen and suspended solids in a SSHF constructed wetland in Capinha, PortugalPublication . Arendacz, Mirosława; Obarska-Pempkowiak, Hanna; Albuquerque, António; Correia, Maria; Borges, MiguelComparing with other countries there is still a lack of experience in applied constructed wetlands for wastewater treatment in Portugal. Among all Mediterranean countries only France and Italy established the guidelines on Constructed Wetlands (CWs). In most of those countries as well as in Portugal there are no specific regulations and design criteria of CWs for the treatment of wastewater [1]. Most of the CWs applied in Mediterranean countries were designed basing on northern countries experience; therefore there is a great need to establish regulations suitable for warm climate conditions. Additionally, the extending popularity of CW systems and a need to make more researches is forced by the Urban Wastewater Treatment Directive (91/271/EEC) and Water Framework Directive (2000/60/EEC), which set the goals to achieve certain standards of discharge water in Europe by the 2015 year. The advantages of CWs application in Portugal are unquestionable: low energy and maintenance requirements, low cost and appropriateness for domestic wastewater treatment for small and rural communities. Moreover, the land availability and temperature are not the limiting factors. As almost 25% of 5 Mirosława Arendacz, Hanna Obarska-Pempkowiak, Antonio Albuquerque, Maria Correia, Miguel Borges the population of central Portugal lives in small and rural agglomerations CWs seem to be very attractive solution. The majority of constructed wetlands in Portugal are designed as surface horizontal flow systems for secondary treatment of municipal and domestic sewage [2, 3]. There is very little date on the treatment efficiency of CWs in Portugal so far, however it had been reported that they show good performance in terms of BOD5 , TSS and lower effectiveness for total P and N removal. High capacity to remove low concentration of organic substances was also observed [2]. Data obtained on the treatment efficiency of CWs in Mediterranean countries also proved good potential of CWs to organic removal (COD, BOD5, and TSS) as well as to ammonia removal, which enabled meeting discharge criteria set by governments [1]. The survey conducted for CWs in Spain reported that the loadings applied for horizontal flow systems were in range of 0.8÷20.3 g BOD5 /m2day and 3÷17 g TSS/ m2day [4]. Data obtained in Spain showed that the average load applied to horizontal flow constructed wetlands is higher that ones cited in the literature and proved that those systems perform very well in terms of organic matter removal comparing to the other European countries [4]. This conclusion could also apply to Portugal due to similar climate conditions, close localization and similar regulations and criteria taken into account for sizing. However, more accurate data must be provided in order to approve it and to establish the most guidelines criteria. The objective of the paper was to evaluate the performance of the subsurface horizontal flow (SSHF) submerged constructed wetland in Capinha, located in the central Portugal, mostly in terms of organic matter (COD), nitrogen forms (total N, ammonia and nitrate) and suspended solids (TSS). The aim of the work was also to study the effect of loads on the removal of above pollutants.
- Investigation of lab-scale horizontal subsurface flow constructed wetlands treating industrial cork boiling wastewaterPublication . Gomes, Arlindo; Silva, Lúcia; Albuquerque, Antonio; Simões, Rogério; Stefanakis, AlexandrosThe feasibility and treatment efficiency of horizontal subsurface flow constructed wetlands (HSFCW) was assessed for the first time for cork boiling wastewater (CBW) through laboratory experiments. CBW is known for its high content of phenolic compounds, complex composition of biorecalcitrant and toxic nature. Two lab-scale units, one planted with Phragmites australis (CWP) and one unplanted (CWC), were used to evaluate the removals of COD, BOD, total phenolic compounds (TPh) and decolourization over a 2.5-years monitoring period under Mediterranean climatic conditions. Seven organic and hydraulic loading rates ranging from 2.6 to 11.5 g COD/m2/d and 5.7e9.1 L/m2/d were tested under average hydraulic retention time (HRT) of 5 ± 1 days required due to the CWB limited biodegradability (i.e., BOD5/ COD of 0.19). Average removals of the CWP exceeded those of the CWC and reached 74.6%, 91.7% and 69.1% for COD, BOD5 and TPh, respectively, with respective mass removals rates up to 7.0, 1.7 and 0.5 (in g/m2/d). Decolourization was limited to 35%, since it mainly depends on physical processes rather than biodegradation. CBW concentration of nine phenolic compounds ranged from 1.2 to 38.4 mg/L (for the syringic and ellagic acids, respectively) in the raw CBW, with respective removals in the CWP unit ranging from 41.8 to 76.3%, higher than those in the control unit. Despite CBWhigh concentration of TPhs (average of 116.3 mg/L), the HSFCW reached organic load removals higher than those of conventional biological treatment methods.
- Cork Boiling Wastewater Treatment in Pilot Constructed WetlandsPublication . Gomes, A.C.; Stefanakis, Alexandros; Albuquerque, António; Simões, Rogériomost studies published on the topic of cork boiling wastewater (CBW) treatment or valorization used physico-chemical treatment options rather than biological processes. However, the related costs are high and above those of the biological treatment alternative for wastewaters with similar organic loads but from different sources. Thus, con- structed wetland systems (CWs) can be an alternative to conventional biological treatment systems, namely to activated sludge systems, with the prominent virtues of low construction and operation costs. Until today, there is no study or research published for the treatment of CBW using CW systems. Thus, this investigation is a novelty and included the monitoring over a period of four years of the operation of a horizontal subsurface flow constructed wetland (HSF CW) microcosm-scale system planted with common reeds (Phragmites australis) and filled with light expanded clay aggregates (LECA), as support media for the plants and for biofilm development. The contribution of plants to the treatment was assessed by the comparison with an identical wetland unit without plantation (control bed). After this extended period of operation intended to maximize biomass development and acclimatization, which included stepwise increase of the organic load rate (OLR) up to 8.9 g COD/m2/d, the assessment of the treatment capacity of the system was done by doubling the OLR to 16.4 g COD/m2/d during 200 days.