| 1. |
- Baniya, Bishal
(författare)
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A theoretical study of the potential for metal extraction from the incinerated ashes residing in Swedish landfills
- 2013
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Ingår i: Environmental technology. - : Taylor and Francis. - 0959-3330 .- 1479-487X. ; 34:7, s. 891-900
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, waste incineration has played a major role in sustainable waste management, as well as generating combined heat and electricity for many years. Incineration of combustible waste produces residues such as fly ash and bottom ash. The chemical composition of both ashes shows that they consist of bulk metals and scarce metals in significant quantity, in elemental form as well as in small metal pieces, which remain unsorted from the incinerated residues. This shows the potential for metal extraction from the ashes, which are deposited in Swedish landfills. Thus with the aim of quantifying selected metals (Al, Cu, Fe, Zn, Sb, Sn, Ni, Co, Mo, Ti and V), and assessing their flows and stocks in different deposits, this study has been carried out. Approximately 50% of grate plants and 30% of fluidized bed plant in Sweden were sampled for the study. The data collected from the sampled plants were the basis for the calculation of flow of ashes and metals through all the plants. First of all, annual metal flows for 19852010 were estimated, based on which accumulated stocks at different deposits were calculated.
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| 2. |
- Bauer, Torben, et al.
(författare)
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Co-digestion of sewage sludge and wood fly ash
- 2022
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Ingår i: Environmental technology. - : Taylor & Francis. - 0959-3330 .- 1479-487X. ; 43:12, s. 1853-1859
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Tidskriftsartikel (refereegranskat)abstract
- This study uses a new approach for the recycling of plant nutrients by co-digesting sewage sludgewith fly ash from a wood combustion. Sewage sludge and fly ash both are enriched with nutrientsof the wastewater resp. wood, which makes these products an enhanced source for recycledfertilizers. The effects of the ash addition to the anaerobic digestion are studied in several labscale experiments including effects on the gas production and microbial activity. Following that,the fertilizing qualities of the digestate are evaluated by plant growth experiments. The resultsshow that the fertilizing qualities of the digested sludge were improved by the ash addition.Next to this, gas production results show that the methane production was not affected by theash addition, while the total gas release was reduced. The sulphur addition by the ashstimulated sulphate reducing bacteria. The sulphate reducing bacteria did not markedly inhibitthe methanogens.
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| 3. |
- Benazzi, F, et al.
(författare)
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On-line estimation and detection of abnormal substrate concentrations in WWTPs using a software sensor: A benchmark study
- 2007
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Ingår i: Environmental Technology. - 1479-487X. ; 28:8, s. 871-882
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a new approach for on-line monitoring and detection of abnormal readily biodegradable substrate (SS) and slowly biodegradable substrate (XS) concentrations, for example due to input of toxic loads from the sewer, or due to influent substrate shock load, is proposed. Considering that measurements of SS and XS concentrations are not available in real wastewater treatment plants, the SS | XS software sensor can activate an alarm with a response time of about 60 and 90 minutes, respectively, based on the dissolved oxygen measurement. The software sensor implementation is based on an extended Kalman filter observer and disturbances are modelled using fast Fourier transform and spectrum analyses. Three case studies are described. The first one illustrates the fast and accurate convergence of the extended Kalman filter algorithm, which is achieved in less than 2 hours. Furthermore, the difficulties of estimating XS when off-line analysis is not available are depicted, and the SS | XS software sensor performances when no measurements of SS and XS are available are illustrated. Estimation problems related to the death-regeneration concept of the activated sludge model no.1 and possible application of the software sensor in wastewater monitoring are discussed.
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| 4. |
- Bengtsson, Simon, 1977, et al.
(författare)
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A comparison of aerobic granular sludge with conventional and compact biological treatment technologies
- 2019
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Ingår i: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 40:21, s. 2769-2778
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Tidskriftsartikel (refereegranskat)abstract
- The aerobic granular sludge (AGS) technology is growing towards becoming a mature option for new municipal wastewater treatment plants and capacity extensions. A process based on AGS was compared to conventional activated sludge processes (with and without enhanced biological phosphorus removal), an integrated fixed-film activated sludge (IFAS) process and a membrane bioreactor (MBR) by estimating the land area demand (footprint), electricity demand and chemicals’ consumption. The process alternatives compared included pre-settling, sludge digestion and necessary post-treatment to achieve effluent concentrations of 8 mg/L nitrogen and 0.2 mg/L phosphorus at 7°C. The alternative based on AGS was estimated to have a 40–50% smaller footprint and 23% less electricity requirement than conventional activated sludge. In relation to the other compact treatment options IFAS and MBR, the AGS process had an estimated electricity usage that was 35–70% lower. This suggests a favourable potential for processes based on AGS although more available experience of AGS operation and performance at full scale is desired.
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| 5. |
- Bhatnagar, Amit, et al.
(författare)
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Assessment of the biosorption characteristics of lychee ( Litchi chinensis) peel waste for the removal of Acid Blue 25 dye from water
- 2010
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Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 31, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the adsorption potential of lychee (Litchi chinensis) peel waste for the removal of Acid Blue 25 dye from aqueous solutions. The adsorption was studied as a function of contact time, initial dye concentration and temperature by batch method. Equilibrium sorption isotherms showed that the lychee peel adsorbent possessed a high affinity and sorption capacity for Acid Blue 25, with a monolayer sorption capacity of ca. 200 mg g-1. The equilibrium adsorption data were well described by the Langmuir model. Kinetic studies revealed that the present system of dye adsorption on lychee peel adsorbent could be described more favourably by the pseudo-second-order kinetic model. The thermodynamic parameters, namely free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) changes, were determined for the process. The results of the present study suggest that lychee peel waste can be used beneficially as an adsorbent in treating industrial effluents containing dyes.
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| 6. |
- Bhatnagar, Amit, et al.
(författare)
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Review on the use of red mud as adsorbent for the removal of toxicpollutants from water and wastewater
- 2011
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Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 32:3, s. 231-249
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Tidskriftsartikel (refereegranskat)abstract
- Red mud (an aluminium industry waste) has received wide attention as an effective adsorbent for water pollution control, showing significant adsorption potential for the removal of various aquatic pollutants. In this review, an extensive list of red‐mud‐based adsorbents has been compiled and their adsorption capacities (maximum uptake value of the adsorbent for the pollutant or adsorbate being removed) for various aquatic pollutants (metal ions, dyes, phenolic compounds, inorganic anions) are presented. The review provides a summary of recent information obtained using batch studies and deals with the adsorption mechanisms involved. It is evident from the literature survey that red mud has been found to be efficient for the removal of various aquatic pollutants, especially arsenic and phosphate. However, there is still a need to investigate the practical utility of these adsorbents on a commercial scale.
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| 7. |
- Björklund, Karin, 1979, et al.
(författare)
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Sorption of organic pollutants frequently detected in stormwater: evaluation of five potential sorbents
- 2018
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Ingår i: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 39:18, s. 2335-2345
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption filtration is one of the most promising techniques for removal of dissolved, colloidal and particulate pollutants from stormwater. The aim of this study was to compare the capacity of five filter materials – cellulose, chitosan, chitosan-covered bark, pine bark and polypropylene/polyethylene (PP/PE) fibres – to sorb organic pollutants frequently detected in stormwater, including polycyclic aromatic hydrocarbons (PAHs), alkylphenols and phthalates. In batch tests, synthetic stormwater spiked with a mixture of the organic compounds was contacted with the materials for up to 24 h. The compounds were then liquid–liquid extracted and analysed using GC-MS. Cellulose and chitosan showed very low sorption capacity for the organic contaminants, whereas >70% of the initial concentration of most tested compounds was removed using PP/PE fibres, and >80% with pine bark and chitosan-covered bark. The highest adsorption capacity was found for PAHs (up to 44 μg/g) using PP/PE fibres and bark. For all tested compounds, maximum sorption was approached within 30 min using these materials.
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| 8. |
- Björkqvist, Susan, 1967, et al.
(författare)
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Hydrocarbons in biogas from household solid waste
- 1998
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Ingår i: Environmental Technology (United Kingdom). - 1479-487X .- 0959-3330. ; 19:6, s. 639-642
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Tidskriftsartikel (refereegranskat)abstract
- The components of biogas from source-separated domestic waste were studied for the first major Swedish plant (Sobacken, Boras) in operation. Methane, carbon dioxide and C-6-C-11 hydrocarbons were determined by gas chromatographic methods. The content of methane was found to be just over 70% (v/v). The major polluting hydrocarbon in the biogas was p-cymene. It may be formed by rearrangement and dehydrogenation of limonene and other monoterpenes in food waste.
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| 9. |
- Bohn, Irene, et al.
(författare)
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Effect of temperature decrease on the microbial population and process performance of a mesophilic anaerobic bioreactor
- 2007
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Ingår i: Environmental Technology. - 1479-487X. ; 28:8, s. 943-952
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Tidskriftsartikel (refereegranskat)abstract
- The effect of a temperature decrease from 33 degrees C to 12 degrees C was investigated for anaerobic digestion of crop residues. A laboratory-scale reactor (R,) was inoculated with mesophilic sludge and operated as continuously stirred fed-batch system at temperatures of 12 degrees C, 18 degrees C and 33 degrees C. Changes in the microbial populations of the sludge were followed by means of fluorescence in situ hybridization analysis. Methane was produced in R, at all temperatures. Stable long-term operation at 18 degrees C was achieved yielding 151 mlCH(4) gVS(added)(-1) at a rate of 108 mlCH(4) l(R)(-1)d(-1) once the microbial populations of the sludge had adapted to this temperature. After operation at 18 degrees C, the contents of R-0, was mixed and distributed into three smaller reactors, which were operated at 18 degrees C (R-18), 25 degrees C (R-25) and 37 degrees C (R-37) respectively. Methane production rates for R-37 and R-25 were 366 and 310 mlCH(4) l(R)(-1)d(-1), respectively, which were higher than the 215 mlCH(4) l(R)(-1)d(-1) obtained in R-0 when this was operated at 33 degrees C. Hydrolysis was found to decrease when temperature was decreased and especially below 25 degrees C. At temperatures below 16 degrees C, acidogenesis and methanogenesis were the rate-limiting steps. Adaptation of the mesophilic sludge to 18 degrees C was indicated by an increase in the ratio of Bacteria to total prokaryotes (sum of Archaea and Bacteria). This was thought to be caused by enrichment of Bacteria in the sludge, which appeared to be an important adaptation mechanism. During the adaptation, the Methanomicrobiales and Methanosarcinaceae populations increased relative to the total Archaea population whereas the Methanosaeta population decreased. The population changes were reflected by reactor performance.
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| 10. |
- Chaudhary, Ramjee, et al.
(författare)
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Kinetic study of nutrients removal from municipal wastewater by Chlorella vulgaris in photobioreactor supplied with CO2-enriched air
- 2020
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Ingår i: Environmental technology. - : TAYLOR & FRANCIS LTD. - 0959-3330 .- 1479-487X. ; 41:5, s. 617-626
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Tidskriftsartikel (refereegranskat)abstract
- The microalgae Chlorella vulgaris ATCC 13482 was used in the present study for municipal wastewater treatment. Batch experiments were performed in bubble column photobioreactors of 7 L working volume maintained at 25 +/- 2 degrees C and 14 h/10 h of photo and dark cycle. The treatment process was enhanced by using CO2-augmented air (5% CO2 v/v) supply into the microalgal culture in comparison to the use of normal air (0.03% CO2 v/v). For a period of 7 days, C. vulgaris effected maximum removals of 74.4% soluble fraction of chemical oxygen demand, 72% ammonia (NH4-N), 60% nitrate (NO3-N) and 81.93% orthophosphate (PO4-P) with use of normal air, whereas 84.6% sCOD, 88% NH4-N, 72% NO3-N and 92.8% PO4-P removals, respectively, with use of 5% CO2/air supply. Using kinetic study data, the specific rates of ammonia and phosphate uptake (q(ammonia) and q(phosphate)) by C. vulgaris at 5% CO2/air supply were found to be 2.41 and 0.85 d(-1), respectively. Using the algal remediation technology, nitrogen-phosphorus-potassium recovery from sewage treatment plant of 37.5 million litres per day wastewater influent capacity was calculated to be similar to 298.5, 55.4 and 83.7 kg d(-1), respectively.
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