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Fitorremediación de aguas residuales industriales mediante humedales artificiales para uso agrícola
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Recent progress on Aerobic Inverse Fluidized Bed Biofilm Reactors (AIFBBRs) used for treatment of various
industrial wastewaters is discussed in this article. For the effective operation of AIFBBRs, knowledge of phase
holdup, pressure gradient, phase flow rates, minimum fluidization velocity, friction factor, bubble size and rise
velocity; mass & heat transfer coefficients; residence time distribution; and settled bed to bioreactor volume ratio
are essential. In this regard different aspects of AIFBBRs such as static bed height and shape, size, density, & type
of carrier particles have been analyzed. Knowledge of the reaction conditions (time, temperature, and pH), type
of microorganisms and nutrients, concentration of pollutants, and thickness of biomass growth on carrier particles
are also essential. Various literatures reveal that AIFBBRs have better operational stability and have higher
organic matter removal capacity. Future research aspects of AIFBBRs are also discussed in this article.
Two constructed wetlands for treating industrial and sewage effluents (CW1 and CW2) and two natural wetlands (NW1 and NW2), located in Argentina, were studied. The aims of the study were (1) to assess the accumulation and distribution pattern of P in the surface sediments of both natural and constructed wetlands, and (2) to evaluate P long-term retention in sediment. In the sediment of all study sites, inorganic P fractions were dominant. Similar incoming water composition was determined between NW2 and CW1 and between NW1 and CW2. Water composition governed P concentration and distribution in sediment, being mainly P bound to CaCO3 in CW1 and NW2 and bound to Fe(OOH) in NW1 and CW2. According to water and sediment characteristics, the four wetlands will continue removing P from water. Studied wetlands are efficient and sustainable in terms of P retention.
The lake of Bosque de San Juan de Aragón (LBSJA, for its Spanish acronym), occupies a 12 hectare area. The lake is eutrophicated due to an activated sludge system, known as “Tlacos”, that carries partially treated water into the lake and contains nitrogen and phosphorus concentrations that trigger the growth of microalgae. In this study, we describe relevant aspects of the design, construction and operational start of a treatment system based on artificial wetlands (AWs) built in the LBSJA. The AWs occupies an area of about one hectare; it was designed to purify an average of 250 m3d−1 of water. The system consists of a limestone aggregate filter, a settler, a subsurface flow artificial wetland (SSFAW), a surface flow artificial wetland (SFAW), and a gabion wall filter. Water that feeds the system comes from both the conventional treatment plant of “Tlacos” (WWTP-Tlacos) and that contained in the lake itself. Our results show an 80% reduction of contaminant content. The later represents a superior quality than that established in the environmental standards for treated water from water bodies used for recreational purposes.
A horizontal subsurface flow reed bed, Pragmites australis, constructed wetland system was operated continuously for one year at 5 different hydraulic retention times between 5 days-11 days with real tannery industry effluent to investigate mainly NH4-N and COD removal performance of the system. The bed was also operated at different initial NH4-N concentrations between 10-30 mg/L by adding NH4Cl into the tannery effluent. The results indicated that ammonia-nitrogen removal is significantly affected by hydraulic retention time while COD is not. The optimum HRT was determined as 8 days with over 95% NH4-N and around 30% COD removal efficiency. The system shows higher removal performance at high initial NH4-N concentrations. Almost complete (99%) NH4-N removal and over 40% COD removal was obtained at (NH4-N)0 = 20 mg/L and HRT = 7 days. PO4-P and total chromium removal were not significantly affected by operating conditions
Bioaugmentation of activated sludge processes through the addition of microorganisms is employed with the aim of enhancing treatment, in particular the removal of priority pollutants. With industrial wastewaters, studies have covered target pollutants including ammonia and polycyclic aromatic hydrocarbons (PAHs): compounds that are regulated around the globe. However, bioaugmentation is a technique that has been associated with doubt in regard to its ability to benefit treatment processes. Failure of bioaugmentation has been reported to be associated with numerous factors that include the growth rate being lower than the rate of washout, insufficient inoculum size and substrate availability. Limitations of bioaugmentation can be overcome through techniques that include increased inocula dosing, pre-acclimatisation of inocula in side-stream reactors, addition of nutrients and surfactants and application of sufficient acclimatisation periods. Surveys of the literature show that a key area for further research should be towards acquiring a better understanding of the degradation pathways where bioaugmentation is applied. There also remains a need to undertake bioaugmentation efficacy studies at full scale with test and control streams. Further reporting on the economic viability of the technique is also necessary.
To implement tariffs and regulations on sanitation and wastewater treatment, as well as for disposal or reuse of treated effluents, it is necessary to know the treatment technologies, which one would be best adapted to the present circumstances of any site and finally if the treated wastewater can be disposed of, legally or reused complying the rules and regulations, in a safe way.
Wastewater treatment has been evolving at different pace along the history, according to the increasing concentration of people in towns and cities. With the increasing pressures on water resources, concerns on how to find new resources capable to help reaching equilibrium within demand and offer arise. In this context, one of the main possibilities to cope with water scarcity is wastewater reclamation and reuse.
The main features of wastewater treatment and several of the characteristics of reclamation and reuse are developed in this chapter.
Plant samples including roots, stems and leaves of Phragmites australis and Suaeda salsa were collected in the short-term-flooding and tidal-flooding wetlands of the Yellow River Delta of China. Six heavy metals (e.g., As, Cd, Cr, Cu, Pb, and Zn) were measured in roots, stems and leaves of each plant species using inductively coupled plasma atomic absorption spectrometry (ICP-AAS) to investigate the levels, and transfer capabilities of heavy metals in these two plant species. Our results showed that in tidal flooding wetlands, the contents of As, Cr and Cd in roots of Phragmites australis and Suaeda salsa were higher than those in their stems and leaves. Suaeda salsa showed higher contents of Pb and Zn in leaves than those in roots and stems, whereas lower levels of Pb and Zn were observed in Phragmites australis. In the short-term-flooding wetlands, heavy metal contents exhibited a big difference between different tissues of Phragmites australis and Suaeda salsa, and both plant species showed higher levels of Pb and Zn in leaves. Suaeda salsa roots enriched more As and Cd, whereas higher enrichment levels were observed in Phragmites australis leaves, which indicated different transfer capacities of these two wetland plants. The transfer factors for stems and leaves of Phragmites australis in tidal flooding wetlands significantly differed from those in short-term flooding wetlands, however, no significant differences in transfer factors for stems and leaves of Suaeda salsa were observed between these two types of wetlands.
Water resources provide many benefits that generate value for residents and recreation users alike but run-off from agricultural and impervious surfaces can impair water quality, reducing any generated value. A possible solution to this problem is the construction of treatment wetlands to remove excessive nutrients from water bodies. This study uses environmental and economic data to approximate the costs of constructing and operating free surface water wetlands to remove phosphorus and estimates the amenity and recreational benefits of the resulting improvements in water quality for 24 lakes in Ohio. A ten percent improvement in water quality from a decrease in phosphorus loadings generates positive net benefits for all lakes in the sample with a lifetime cost benefit ratio of 2.92. The study also examines the potential use of constructed wetlands as the sole strategy to achieve a reduction goal for phosphorus loadings and find that the costs of doing so are prohibitive. Constructed wetlands can be a cost-effective component of a comprehensive strategy for small-scale nutrient reduction and water quality improvements for surface water bodies, but other treatment methods would be required to achieve any proposed targeted improvements.
Boron (B) pollution is an expanding environmental problem throughout the world due to intensive mining practices and extensive usage of B in agricultural chemicals and industrial products in recent years. The purpose of this study was to investigate B removal performance of four poplar and four willow species in small scale Constructed Wetland (CW). Rooted cuttings of tested species were treated with simulated wastewater having five elevated B concentrations (0.5, 5, 10, 20 and 40 ppm). All the tested species could resist up to 20 ppm wastewater B supply and could regrow from their roots in the soil having maximum 15 mg/kg B content. The result of the study indicated that 65% ± 5.3 of B was removed from the wastewater in 5 ppm B treatment while the same efficiency decreased to 45% ± 4.6 at 40 ppm B supply. The average effect of sediment on B removal was found to be approximately 20% for all B treatments while the remaining part of the loaded B was removed from the CW within effluent (35-54%). Therefore, actual effects of plant species on B removal was ranged from 45% to 25% between 5 and 40 ppm B treatments. Mass B removal within plant body (phytextraction) comprised the 13-10% of total loaded B in CW while the remaining part of the loaded B (31-15%) was stabilized into the sediment with the effects of poplar and willow roots. These results presented clear understanding of effective B purification mechanisms in CWs. Boron phytextraction capacity of a plant species was less effective than its phytstabilization efficiency which increase filtering capacity of the sediment and stabilization of more B around the rhizosphere. In terms of their B removal ability, P.nigra and S.anatolica had the highest B removal capacities with phytextraction (20-11%) while S.alba, P.alba and S.babylonica had more phytstabilizaiton performance (40-15%) in CW. Disposal of B loaded plant material create another environmental costs for CW applications. Therefore, B loaded wood and leaf tissues were mixed and used for production of wooden panels in the study. Then a combustion test was applied on these panels to test their fire resistance. The results of the tests revealed much higher burning tolerance of the B loaded panels (5-20%) compared to controls. Annual harvesting, fast growing and deep rooting ability of the poplar and willow species with their high phytstabilization and phytextraction efficiencies make these species excellent tools to remove B from the polluted waters. Utilization of these species for B removal in large scale CWs is quite possible which should be also investigated in further studies.
The use of phytoremediation systems to enhance the treatment of industrial wastewater coming from a standard depuration process in order to allow their reuse can potentially lead to several interesting benefits (costs savings for depuration processes, freshwater and energy supply with a consequent reduction of the overall environmental impact of the industrial sites). In this work the case study of a large automotive plant (FCA plant in Verrone, Piedmont, NW Italy) was analyzed, with the aim of evaluating the possible application of a phytoremediation system (constructed wetland, CW) to treat the effluents of its existing wastewater treatment plant (WWTP, currently discharged into a watercourse) and reuse them in the industrial processes. For this purpose, a pilot CW system was set up with two different configurations horizontal and vertical. Experiments were carried out to identify the one characterized by the best abatement rate of the pollutant concentrations of the plant effluents. Results showed that the horizontal submerged flow system (HF) was the most efficient phytoremediation system suitable for the aging of the effluents of the existing WWTP in view of their possible reuse in the industrial processes. Furthermore, costs related to its scaling-up for a real application demonstrated that the CW can be the cheaper option compared to a traditional treatment process for wastewater reuse. The amount of treated water which may be reused can range from 55% to 80% of the effluents from the existing WWTP, with a consequent reduction of more than 80% in the current water supply from aquifers.
An understanding of the seasonal variation in the standing stock of metals and nutrients in emergent vegetation of constructed wetlands (CWs), as well as the amounts present in aboveground (AG) and belowground (BG) biomass, is crucial to their design and management. Given that biomass harvesting is a labour and time consuming operation, a paucity of information currently exists on accumulation and standing stocks in biomass in CWs, in particular in North Western European countries. To address this knowledge gap, this paper examined the seasonal variations of metals and nutrients in Phragmites australis (Cav.) Trin. ex Steudel in a CW treating municipal wastewater, with a view to identifying an optimal time for biomass harvesting of the AG vegetation. Although the AG biomass was greatest in August (1636 ± 507 g m⁻²), the maximum concentrations and accumulations of metals and nutrients occurred at different times throughout the duration of the study (April to November). Furthermore, with the exception of zinc and nitrogen, metals and nutrients measured in BG biomass ranged from 66% (phosphorus) to greater than 80% (nickel and chromium) of the AG biomass. This indicates that analysis of only the emergent shoots may significantly underestimate the metal and nutrient uptake and capacity of the plant. In order to effectively target the bulk of metals and nutrients, an AG harvest in late August or September is suggested.
The accumulation of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in the sediment and plants growing in a constructed wetland used to treat highway runoff in Ireland has been quantified after 6 and 9 year periods of operation. The spatial distribution of the metals' deposition showed strong evidence of flow channelling through the wetland with a strong correlation between the spatial accumulation, particularly for Cr, Cu, Pb and Zn with most of these metals deposited towards the front of the wetland in the sediment. Highest accumulation in the wetland was for Zn, followed by Cu, Pb, Cr, Ni and Cd. The study also quantified that an almost negligible mass of metals had accumulated in the vegetation compared to the sediment. However, an apparent increase in metal accumulation with time may be linked to the cumulative annual production and deposition of organic matter, indicating the importance of the vegetation as an integral part of the treatment process. Based on the measured accumulation and projected runoff loads over the 9 year period, the apparent removal efficiencies were 5% (Cd), 60% (Cu), 31% (Pb) and 86% (Zn). This equates to accumulation rates of 0.1 (Cd), 15.6 (Cu), 11.6 (Pb) and 88.3 (Zn) g per m² highway drained per year.
Wastewater treatment and low energy consumption are two important environmental issues. In this work, a challenging treatment problem of leather industry wastewater is chosen as a case study to combine the issue of energy and treatment efficiency using a common denominator of oxygen demand. Tannery wastewater is known for its highly contaminated structure. Due to the acidic nature of the effluent, conventional methods do not perform well for tannery wastes, so an electrochemical process is a reasonable approach for the problem. Since electrochemical reactors use electricity, the energy efficiency of such plants should be simultaneously considered for overall sustainability. The electricity production partially results in carbon footprints and consumption of oxygen. In this work, the electrochemical treatment results were assessed through total chromium removal and chemical oxygen demand (COD) reduction. As expected, the electrochemical process parameters (reactor types, electrode variations, electrical current density, etc.) as well as the process duration affect the treatment performance. Meanwhile, these parameters also affect energy consumption. Although the energy consumption has been previously researched, (i) “the oxygen equivalent of the required energy” and (ii) “oxygen demand reduction of the wastewater” were not considered simultaneously before. In this work, the used energy is represented in terms of consumed oxygen at the current electric generation profile (in Turkey and in USA). It is argued that, as the consumed energy increases, the consumed oxygen also increases, causing a separate pollution (in terms of COD and other indirect effects). The combined production/consumption profiles as well as energy efficient parameter settings are investigated by experiments. It is observed that the combined oxygen demand (i.e. reduced on the treatment side and increased at the power generation side) starts exhibiting an overall increase at early treatment stages. For example, at an electrical current setting of 20 mA/cm² and pH of 7, using electro-coagulation with aluminum electrodes, treatment reaches to 82% COD removal (from 1024 mg/L to 180.71 mg/L) at 8.33 kWh/m³, corresponding to consuming 3.23 g/L oxygen at average energy production settings in Turkey. The oxygen consumption using electro-Fenton exhibits similar results. The necessity of renewable energy utilization or an earlier treatment termination is concluded.
Wastewater treatment in constructed wetlands is a biotechnological process which has been used for more than five decades for wastewater treatment. It is generally agreed that plants are important part of the treatment system, however, the direct role of plants is usually restricted to plant uptake of nutrients and heavy metals. The purpose of this study was to evaluate the amount of heavy metals sequestered in the aboveground biomass of Phragmites australis and thus, available for harvest and removal. The survey revealed that the amount of heavy metals accumulated in the aboveground plant biomass (aboveground standing stock) represents often only small fraction of the inflow annual load but in some studies, this fraction is quite high, especially for zinc (up to 59%), more rarely for cadmium (55%) and chromium (38%). The amount of heavy metals sequestered in the plant shoots as a fraction of total removed heavy metal in the constructed wetland is variable with values as high as 71% for cadmium, 55% for chromium or 49% for zinc in some studies. However, there is still a large gap in our knowledge on heavy metal accumulation in aboveground tissues, namely the conditions that would promote heavy metal uptake and subsequent translocation to aboveground biomass.
The development of new tanning agents and new technologies in the leather sector is required to cope with the increasingly higher environmental pressure on the current tanning materials and processes such as tanning with chromium salts. In this paper, the use of titanium wastes (cuttings) resulting from the process of obtaining highly pure titanium (ingots), for the synthesis of new tanning agent and tanning bovine hides with new tanning agent, as alternative to tanning with chromium salts are investigated. For this purpose, Ti waste and Ti-based tanning agent were characterized for metal content by inductively coupled plasma mass spectrometry (ICP-MS) and chemical analysis; the tanned leather (wet white leather) was characterized by Scanning Electron Microscope/Energy Dispersive Using X-ray (Analysis). SEM/EDX analysis for metal content; Differential scanning calorimetric (DSC), Micro-Hot-Table and standard shrinkage temperature showing a hydrothermal stability (ranged from 75.3 to 77 °C) and chemical analysis showing the leather is tanned and can be processed through the subsequent mechanical operations (splitting, shaving). On the other hand, an analysis of major minor trace substances from Ti-end waste (especially vanadium content) in new tanning agent and wet white leather (not detected) and residue stream was performed and showed that leachability of vanadium is acceptable. The results obtained show that new tanning agent obtained from Ti end waste can be used for tanning bovine hides, as eco-friendly alternative for chrome tanning.
Murphy and Riley proposed use of a single reagent for determining P. The method was found to be accurate for determining P in soil extracts. This method is based on reduction of the ammonium molybdiphosphate complex by ascorbic acid in the presence of antimony. The color produced is stable for 24 hours. It is less subject to interfering substances than are methods involving reduction by SnCl 2 .
Reducing the environmental impact of the unhairinga liming process in the leather tanning industry
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process in the leather tanning industry. J. Cleaner Prod. 2006, 14, 65-74.
Council Directive of 12 December 1991 Concerning the Protection of Waters Against Pollution by Nitrates from Agriculture Sources (91/676/ EEC)
- P Duchaufour
- Precis De Pedologie
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