A number of advantages are claimed for dual digestion as a system for sewage sludge pasteurisation and stabilisation. In this paper, the first of a series of 4, an overview of a 4-year full-scale (45 ...m3 aerobic reactor and 500 m3 anaerobic digester) dual digestion research project is presented. The project was undertaken at Milnerton (Cape, South Africa) and its principal objective was to evaluate the claims made for the dual digestion system. In this paper the claims are stated; the layout and operation of the dual digestion system described; the main results obtained briefly discussed; and the claims evaluated with the aid of the results. It is concluded that most of the claims are valid, inter alia; the mesophilic anaerobic digester performance is not adversely affected by the first stage autothermal thermophilic aerobic reactor compared to conventional digestion. The 3 sequel papers focus attention on the aerobic reactor; its operation, performance, control, design and simulation of the temperature profile for both air and pure oxygen systems.
EN Every year, more and more tones of urban toxic waste have to be disposed of. The rate of generation of this type of waste has increased in such a scale that it has even produced a rupture between ...the planet biosphere and human activities. In due course, if an appropriate treatment is not carried out along with a correct waste management enormously damaging consequences are expected in economic, social and technological development and environmental terms. Nevertheless, nearly all material arriving to plants is revalued with the main purpose of generating the least possible rejecting. Recycling together with composting are the main systems that allow the possibility of reusing organic waste. The modification of the Integral Plan of Waste in the Comunitat Valenciana (PIRCV) within the 81/2013 decree, is aimed at promoting a new model of waste management mainly built on a circular economy intending to reach zero waste emissions. Promoting the use of waste in cascade along with the maximizing of available resources as much in energy as in material terms are the basic of this model. This Project refers to the starting of a fermentation reactor, a permanent classification and revaluation plant devoted to home waste. This plan to analyze the management of the bioestabilization process based on the control of the main parameters, namely, temperature, humidity, pH level, pressure and finally the velocity of the forced aspiration system as well as the correct oxygenation of materials.
ES Cada año son más las toneladas de residuos sólidos urbanos que hay que eliminar. Las tasas de generación de estos residuos se han incrementado llegando a producir una ruptura entre la biosfera del planeta y las actividades humanas que a la larga si no se realiza un correcto tratamiento y una buena gestión de los residuos puede conllevar un gran problema a nivel económico, desarrollo social, tecnológico y sobre todo ambiental. No obstante, casi todos los materiales que llegan a la planta se revalorizan, con el objetivo principal de generar el mínimo rechazo posible. El reciclaje junto al compostaje son los principales sistemas que permiten reaprovechar los residuos orgánicos. Con la modificación del Plan Integral de Residuos de la Comunidad Valenciana (PIRCV) del decreto 81/2013, pretende impulsar un nuevo modelo de gestión de residuos, basados principalmente en una economía circular, políticas basadas al residuo cero. Fomentar la utilización de residuos en cascada y maximizar los recursos disponibles tanto energéticos como materiales, es la base de este modelo. Este proyecto trata de la puesta en marcha de un reactor de fermentación, de una planta fija de clasificación y valorización de residuos domiciliarios, en el cual se pretende analizar el control del proceso de bioestabilización, basados el control de los parámetros principales, que son la temperatura, la humedad, el pH, la presión y la velocidad del sistema de aspiración forzada, así como la correcta oxigenación del material.
ES Cada año son más las toneladas de residuos sólidos urbanos que hay que eliminar. Las tasas de generación de estos residuos se han incrementado llegando a producir una ruptura entre la biosfera del planeta y las actividades humanas que a la larga si no se realiza un correcto tratamiento y una buena gestión de los residuos puede conllevar un gran problema a nivel económico, desarrollo social, tecnológico y sobre todo ambiental. No obstante, casi todos los materiales que llegan a la planta se revalorizan, con el objetivo principal de generar el mínimo rechazo posible. El reciclaje junto al compostaje son los principales sistemas que permiten reaprovechar los residuos orgánicos. Con la modificación del Plan Integral de Residuos de la Comunidad Valenciana (PIRCV) del decreto 81/2013, pretende impulsar un nuevo modelo de gestión de residuos, basados principalmente en una economía circular, políticas basadas al residuo cero. Fomentar la utilización de residuos en cascada y maximizar los recursos disponibles tanto energéticos como materiales, es la base de este modelo. Este proyecto trata de la puesta en marcha de un reactor de fermentación, de una planta fija de clasificación y valorización de residuos domiciliarios, en el cual se pretende analizar el control del proceso de bioestabilización, basados el control de los parámetros principales, que son la temperatura, la humedad, el pH, la presión y la velocidad del sistema de aspiración forzada, así como la correcta oxigenación del material.
EN Every year, more and more tones of urban toxic waste have to be disposed of. The rate of generation of this type of waste has increased in such a scale that it has even produced a rupture between the planet biosphere and human activities. In due course, if an appropriate treatment is not carried out along with a correct waste management enormously damaging consequences are expected in economic, social and technological development and environmental terms. Nevertheless, nearly all material arriving to plants is revalued with the main purpose of generating the least possible rejecting. Recycling together with composting are the main systems that allow the possibility of reusing organic waste. The modification of the Integral Plan of Waste in the Comunitat Valenciana (PIRCV) within the 81/2013 decree, is aimed at promoting a new model of waste management mainly built on a circular economy intending to reach zero waste emissions. Promoting the use of waste in cascade along with the maximizing of available resources as much in energy as in material terms are the basic of this model. This Project refers to the starting of a fermentation reactor, a permanent classification and revaluation plant devoted to home waste. This plan to analyze the management of the bioestabilization process based on the control of the main parameters, namely, temperature, humidity, pH level, pressure and finally the velocity of the forced aspiration system as well as the correct oxygenation of materials.
The aim of this study was to investigate the effect of nanoscale zero-valent iron (nZVI) on the formation of aerobic granules, nutrient removal and bacterial growth during the treatment process of ...the municipal wastewater. For this purpose, two sequencing batch reactors (SBR) were simultaneously and automatically operated in a cyclic batch mode with four phases per cycle: feed, react, settle and decant. The sequancial operation of the reactors consisted four cycles per day and lasted for sixty days in which 10 mg/L of nZVI particles were added to the infflent of reactor 2. The reactors were fed with synthetic wastewater (3 liters per cycle) and acclimated with seed sludge collected from a full-scale municipal wastewater treatment plant in Istanbul. The effluent of the reactors was regularly analyzed for nitrate, nitrite, ammonia, phosphate and COD concentrations. In addtion to that, their removal pathways including the direct adsorption to nZVI, utilization by microorganisms and adsorption within the generated granules were discussed. The removal efficiency of COD, ammonia and phosphate kept increasing, and almost a complete removal was observed after the formation of aerobic granules on day 50. Furthermore, after the addition of nZVI to R2 on day 24th, the removal efficiency of ammonia, COD and phosphate slightly improved. The addition of nZVI stimulated the production of Extracellular Polymeric Substances (EPS) in R2 including protein and carbohydrate generation. NGS analysis showed that the addition of nZVI into R2 increased the growth rate of some bacterial species such as Rhizobiales and Xanthomonadales and decreased others such as Clostridiales, confirming that the effect of nZVI on the bacterial growth was genera dependent. The aerobic granules were successfully formed in the reactors in less than 50 days and the addition of nZVI improved to some extent the size and settling rate of the formed granules in R2.
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•The effect of nZVI on the bacterial growth was genera dependent.•nZVI had a positive effect on the the generation of EPSs.•The aerobic granules were formed in less than 50 days.•The addition of nZVI slightly enhanced the formation of granules and the removal of pollutants.•Accelerating the formation of aerobic granules requires a short settling time.
Anoxic-aerobic sequential moving-bed reactors were operated for the degradation of synthetic petroleum refinery wastewater containing phenol (750 mg/L), hydrocarbons (1250 mg/L), S
2−
(750 mg/L), NH
...4
+
-N (350 mg/L), NO
3
-
N (1000 mg/L) and surfactant as nonylphenol-monoethoxylate (0.2 mmol/L). Kerosene, heavy oil and their mixture were used as hydrocarbon source. Anoxic reactor was a disc-bed reactor and aerobic reactor was moving-bed reactor operated at hydraulic retention times (HRT) of 48 and 16 h respectively at 27 ± 3°C. In anoxic reactor, removals of S
2−
and NO
3
-
N were more than 99% along with 50-60% removal of hydrocarbons and phenol. Removal of organics deteriorated in anoxic reactor with heavy oil in feed having higher density and viscosity. Residual organics and NH
4
+
-N were removed in aerobic reactor with more than 99% efficiency. Biomass activity decreased in anoxic reactor and increased in aerobic reactor with an increase in density and viscosity of hydrocarbon in feed. Abiotic study confirmed most of the removals were due to biodegradation.
Water from six points from the Riachuelo-Matanza basin was analyzed in order to assess ibuprofen biodegradability. In four of them biodegradation of ibuprofen was proved and degrading bacterial ...communities were isolated. Biodegradation in each point could not be correlated with sewage pollution. The indigenous bacterial community isolated from the point localized in the La Noria Bridge showed the highest degradative capacity and was selected to perform batch and continuous degradation assays. The partial 16S rRNA gene sequence showed that the community consisted of Comamonas aquatica and Bacillus sp. In batch assays the community was capable of degrading 100 mg L
−1
of ibuprofen in 33 h, with a specific growth rate (μ) of 0.21 h
−1
. The removal of the compound, as determined by High performance liquid chromatography (HPLC), exceeded 99% of the initial concentration, with a 92.3% removal of Chemical Oxygen Demand (COD). In a down-flow fixed-bed continuous reactor, the community shows a removal efficiency of 95.9% of ibuprofen and 92.3% of COD for an average inlet concentration of 110.4 mg. The reactor was kept in operation for 70 days. The maximal removal rate for the compound was 17.4 g m
−3
d
−1
. Scanning electron microscopy was employed to observe biofilm development in the reactor. The ability of the isolated indigenous community can be exploited to improve the treatment of wastewaters containing ibuprofen.
Animal wastes have been successfully employed in anaerobic biogas production, viewed as a pragmatic approach to rationalize energy costs in animal farms. Effluents resulting from that process however ...are still high in nitrogen such that attempts were made to couple biological nitrogen removal (BNR) with anaerobic digestion (AD). The demand for organic substrate in such system is partitioned between the anaerobic metabolism in AD and the heterotrophic denitrification cascade following the autotrophic nitrification in BNR. Investigation of underlying N-converting taxa with respect to process conditions is therefore critical in optimizing N-removal in such treatment system. In this study, a pilot-scale intermittently aerated BNR bioreactor was started up either independently or in series with the AD bioreactor to treat high-strength swine waste slurry. The compositions of NH
3-oxidizing bacteria (AOB),
NO
2
-
-oxidizing bacteria (NOB) and denitrifiers (
nosZ gene) were profiled by polymerase chain reaction-capillary electrophoresis/single strand conformation polymorphism (PCR-CE/SSCP) technique and clone library analysis. Performance data suggested that these two process configurations significantly differ in the modes of biological N-removal. PCR-CE/SSCP based profiling of the underlying nitrifying bacteria also revealed the selection of distinct taxa between process configurations. Under the investigated process conditions, correlation of performance data and composition of underlying nitrifiers suggest that the stand-alone BNR bioreactor tended to favor N-removal via
NO
3
-
whereas the coupled bioreactors could be optimized to achieve the same via a
NO
2
-
shortcut.
Degradation and detoxification of a mixture of persistent compounds (2-chlorophenol, phenol and
m-cresol) were studied by using pure and mixed indigenous cultures in aerobic reactors. Biodegradation ...assays were performed in batch and continuous flow reactors. Biodegradation was evaluated by determining total phenols, ultraviolet spectrophotometry and chemical oxygen demand (COD). Microbial growth was measured by the plate count method. Scanning electronic microscopy was employed to observe the microbial community in the reactor. Detoxification was evaluated by using
Daphnia magna toxicity tests. Individual compounds were degraded by pure bacteria cultures within
27
h
. The mixture of 2-clorophenol
(100
mg
l
−1)
, phenol
(50
mg
l
−1)
and
m-cresol
(50
mg
l
−1)
was degraded by mixed bacteria cultures under batch conditions within
36
h
: 99.8% of total phenols and 92.5% of COD were removed; under continuous flow conditions 99.8% of total phenols and 94.9% of COD were removed. Mineralization of phenolic compounds was assessed by gas chromatography performed at the end of the batch assays and in the effluent of the continuous-flow reactor. Toxicity was not detected in the effluent of the continuous-flow reactor.
