Carex paniculata constructed wetland efficacy for stormwater, sewage and livestock wastewater treatment in rural settlements of mountain areas.

Constructed wetlands are one of the most appropriate wastewater treatment systems in mountain areas, where altitude, slope and climate constitute major environmental and economic constraints for infrastructure construction and subsequent management. In order to protect mountain natural wetland habitats that are sensitive to ecological equilibrium disruption, instead of the more commonly used macrophytes, plant species native to upland wetlands should be preferentially implemented as a contribution to biodiversity conservation and for the creation of more efficient, more resilient and better-adapted constructed wetlands. Carex paniculata is a key macrophyte in several European mountain aquatic habitats, and one of the few high-biomass producers that can grow at sea level and at altitudes of up to 2,600 m. In this paper, the results of a 2-year investigation demonstrate the efficacy of Carex paniculata for the treatment of the mixed stormwater, sewage and livestock wastewater effluents from a typical rural settlement at 825 m above sea level in the Cantabrian Mountains. The year-round suitability of Carex paniculata for the treatment of wastewater with seasonally variable flow and composition in mountain areas is demonstrated.

Impact of silver nanoparticles on benthic prokaryotes in heavy metal-contaminated estuarine sediments in a tropical environment.

Little knowledge is available about the potential impact of commercial silver nanoparticles (Ag-NPs) on estuarine microbial communities. The Hugli river estuary, India, is susceptible to heavy metals pollution through boat traffic, and there is the potential for Ag-NP exposure via effluent discharged from ongoing municipal and industrial activities located in close proximity. This study investigated the effects of commercial Ag-NPs on native microbial communities in estuarine sediments collected from five stations, using terminal restriction fragment length polymorphism (T-RFLP) technique. An increase in the number of bacteria in consortium in sediments was observed following exposure to Ag-NPs. In general microbial communities may be resistant in estuarine systems to the antimicrobial effects of commercial Ag-NPs, but key microorganisms, such as Pelobacter propionicus, disappeared following exposure to Ag-NPs. In conclusion, the T-RFLP analysis indicated that Ag-NPs have the potential to shape estuarine sediment bacterial community structure.

Integrated method in international development for water solutions using the rights-based approach.

The introduction of the rights-based approach to International Development has presented a new set of challenges to those working for the water and sanitation sectors in developing countries. This introduction of this additional pressure on both State and Non-State Actors working in the field has necessitated an overhaul of the existing needs based responses. The engineering solutions and intermediate technology currently available often fail to address the complex requirements of the recipients. This study addresses the change that is required and suggests an integrated engineering approach that will be capable of responding accurately to the requirements of the beneficiary. It proposes an 'integrated method', a way of combining technology, community participation and education.

Bioremediation and biovalorisation of olive-mill wastes.

Olive-mill wastes are produced by the industry of olive oil production, which is a very important economic activity, particularly for Spain, Italy and Greece, leading to a large environmental problem of current concern in the Mediterranean basin. There is as yet no accepted treatment method for all the wastes generated during olive oil production, mainly due to technical and economical limitations but also the scattered nature of olive mills across the Mediterranean basin. The production of virgin olive oil is expanding worldwide, which will lead to even larger amounts of olive-mill waste, unless new treatment and valorisation technologies are devised. These are encouraged by the trend of current environmental policies, which favour protocols that include valorisation of the waste. This makes biological treatments of particular interest. Thus, research into different biodegradation options for olive-mill wastes and the development of new bioremediation technologies and/or strategies, as well as the valorisation of microbial biotechnology, are all currently needed. This review, whilst presenting a general overview, focus critically on the most significant recent advances in the various types of biological treatments, the bioremediation technology most commonly applied and the valorisation options, which together will form the pillar for future developments within this field.

Molecular microbial and chemical investigation of the bioremediation of two-phase olive mill waste using laboratory-scale bioreactors.

Two-phase olive mill waste (TPOMW) is a semisolid effluent that is rich in contaminating polyphenols and is produced in large amounts by the industry of olive oil production. Laboratory-scale bioreactors were used to investigate the biodegradation of TPOMW by its indigenous microbiota. The effect of nutrient addition (inorganic N and P) and aeration of the bioreactors was studied. Microbial changes were investigated by PCR-temperature time gradient electrophoresis (TTGE) and following the dynamics of polar lipid fatty acids (PLFA). The greatest decrease in the polyphenolic and organic matter contents of bioreactors was concomitant with an increase in the PLFA fungal/bacterial ratio. Amplicon sequences of nuclear ribosomal internal transcribed spacer region (ITS) and 16S rDNA allowed identification of fungal and bacterial types, respectively, by comparative DNA sequence analyses. Predominant fungi identified included members of the genera Penicillium, Candida, Geotrichum, Pichia, Cladosporium, and Aschochyta. A total of 14 bacterial genera were detected, with a dominance of organisms that have previously been associated with plant material. Overall, this work highlights that indigenous microbiota within the bioreactors through stimulation of the fungal fraction, is able to degrade the polyphenolic content without the inoculation of specific microorganisms.

Biosorption of phenol and chlorophenols by acclimated residential biomass under bioremediation conditions in a sandy aquifer.

Phenol and chlorophenols are common environmental contaminants. The fate and transport of these chemicals must be sufficiently understood to predict detrimental environmental impacts and to develop technically and economically appropriate remedial action to minimise environmental degradation. In order to gain a better understanding of the many mechanisms influencing the fate of phenol and chlorophenols in a sandy aquifer, we conducted biosorption experiments with biomass collected from a simulated aquifer polluted by consecutive accidental spills of phenol, 2-monochlorophenol, 2,4,6-trichlorophenol and pentachlorophenol under continuous bioremediation conditions following a closed-loop configuration during 180 days. A comparative study of the biosorption capacity of phenol and chlorophenols characterised by different physicochemical properties, at different pHs in the range of 6.0+/-0.1 to 9.0+/-0.1 showed the following: (i) the biosorption of phenol and chlorophenols on resident biomass was rapid (equilibrium reached in less than 2h); (ii) the experimental data followed the Freundlich isotherm; (iii) changes in pH from 6.0+/-0.1 to 9.0+/-0.1 resulted in a decrease in the equilibrium biosorption capacity (qeq); (iv) both Freundlich parameters (KF, n) should be used together as predictive parameters in mathematical models to simulate the fate of phenol and chlorophenols in the aquifer; (v) qeq of phenol and chlorophenols investigated in this study were satisfactorily correlated to their hydrophobicity (Kow) with a correlation factor 0.98. In addition, available data from other reported studies fell in the same correlation curve. The results of the present study should be introduced in mathematical models developed to predict the effect of biomass fate and transport of contaminants in aquifers during bioremediation conditions.

Kinetics of biodegradation during remediation of consecutive accidental spills of chlorophenols in a sandy aquifer.

Kinetics of biodegradation of chlorophenols were studied in six sandy aquifer columns (0.06 m I.D.; 1.00 m L). Remediation of chlorophenols was enhanced by using a "closed-loop" configuration system, where local groundwater was recirculated through the polluted site in a controlled manner. Consecutive accidental spills of phenol, 2-monochlorophenol (2-MCP) and 2,4,6-trichlorophenol (2,4,6-TCP) as single pollutants were removed following first order kinetics. The removal of chlorophenols increased by one order of magnitude following consecutive accidental spills demonstrating adaptation of the resident micro flora. The biodegradation rate constants in this study were in the same range and agreed with those reported in the literature for biodegradation in aerobic aquifers. Following the fate of the resident micro flora (enhanced by adding NH4Cl and KH2PO4 at a ratio C/N/P equal to 120:10:1), biomass growth was observed in the sandy aquifer columns and particle size analyses of the aqueous phase recirculated through the polluted site experimentally proved aggregation of cells. Aggregation of cells has been hypothesized as one of the causes for low biodegradation rates found in the field compared to those calculated using biodegradation rate constants determined in batch culture.

Simulation of bioremediation of chlorophenols in a sandy aquifer.

Bioremediation of consecutive spills of phenol, 2-chlorophenol (2-MCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlororphenol as single pollutants was investigated in eight pilot plant scale sand columns system (100 cm l, 6 cm ID), simulating the conditions, which could be created in the saturated zone of a pristine aquifer following an accidental spill. Bioremediation in this study consisted of re-circulating local groundwater through the polluted site in a controlled manner following a closed-loop configuration. Intrinsic microbial development was enhanced by adding the necessary nutrients. Consecutive accidental spills of 480-mg phenol/kg soil; 140-mg 2-MCP/kg; 14-mg 2,4,6-TCP/kg soil and 17-mg pentachlorophenol (PCP)/kg soil under saturated conditions and a continuous specific discharge of 0.56 cm min(-1) were simulated. Degradation curves demonstrated first-order kinetics. Biodegradation rates (k1) were influenced by consecutive exposures. Calculated rate constants for biodegradation for sole substrate experiments were in the range of 0.06-0.15 day(-1), 0.21-1.20 day(-1), 0.04-2.28 day(-1) and 0.01-0.03 day(-1) for phenol, 2-MCP, 2,4,6-TCP and PCP, respectively. The acclimation of the aquifer to simulated consecutive accidental spills was found to be directly proportional to the cumulative load of each single chlorophenol. A relationship between the octanol water partitioning (Kow) values and the experimental degradation rates (k1) was found.