Environmental Technology

Frycklund, C.; Sundlöf, B.; Jacks, G.

doi: 10.1080/09593332108618099pmid: N/A

In Sweden the properties of groundwater regarding pH, hardness and alkalinity often do not reach the values recommended for drinking water. The problem is more accentuated for artificially recharged groundwater, where infiltration of large volumes of soft surface water eventually leads to a depleted base cation storage. Filters with crushed limestone were embedded in infiltration ponds at two waterworks in Sweden. The effect on the water quality regarding pH, hardness and alkalinity was studied over a period of five years. The filter material was examined. Dissolution of the filter limestone results in increased pH, hardness and alkalinity in the percolating water. To reach levels where it may replace chemical treatment steps in the waterworks, the method needs further development. A more effective use of limestone filters would involve a longer flow path through the filter and a better hydraulic connection between the infiltration pond and the well.

Choung, Y.-K.; Kim, H.-S.

doi: 10.1080/09593332108618103pmid: N/A

Intermittent aeration system with continuous inflow (IASWCI) was fed with synthetic wastewater to clarify the possibility of simultaneous removal of nitrogen, phosphorus, and organic substances by modifying operational schedule. This system was composed of aerobic, anoxic, anaerobic, aerobic, settle and decant phases in a single tank. Synthetic wastewater was flown continuously into the pre-react zone. Anaerobic phase was provided for the phosphorus release without mixing and aerating. The laboratory scale system was operated for four months. Phosphorus release from the sludge was measured in the anaerobic condition after denitrification. The following luxury uptake of phosphorus was observed the second aerobic phase. During 4 months, chemical oxygen demand (COD) removal efficiencies were greater than 90%. The average COD effluent was approximately 17 mgl−1. The effluent had, average, during phosphorus concentration less than 0.5 mgl−1, and ammonia nitrogen concentration lower than 3 mgl−1. A correlation exists between oxidation-reduction potential (ORP) and observed P release in the anaerobic phase, and ORP and measured P uptake in the second aerobic phase. In this case, ORP appears to be related to measured P release and P uptake, as is indicated by the good fit of the linear regression equation. It can be used to good advantage at the operational level to give plant operators a real time indication of P release and uptake condition in this process.

Ha, S. R.; Vinitnantharat, S.

doi: 10.1080/09593332108618107pmid: N/A

Laboratory scale experiments were conducted to evaluate the removal capacities of the major competitive components in a biological activated carbon (BAC) system. Adsorption, desorption, biodegradation, biosorption, and bioregeneration were considered as the major target reactions. Phenol and 2,4-dichlorophenol were used in a single and bisolute system. The adsorption experiment showed that 2,4-DCP was a stronger adsorbate than phenol both in single and bisolute systems. On desorption of 2,4-DCP, the small fraction of sorbed compounds was reversible but phenol had comparatively high reversibility. All solutions exhibited high degrees of irreversible adsorption as hysteresis. Desorption in background organics showed high reversibility. The biomass sorptions of phenol and 2,4-DCP were both negligible so that the removal of these compounds could be disregarded in the BAC system. Meanwhile, the biodegradation of phenol was higher than that of 2,4-DCP in both as a single and bisolute systems. The biodegradation of phenol was higher than that of 2,4-DCP in both single and bisolute systems. Although, the biodegradation capability of phenol was suppressed in the presence of 2,4-DCP but it induced the biodegradation of 2,4-DCP. In single solute, the degree of bioregeneration in terms of phenol and 2,4-DCP in single solute were 76.28% and 56.80%, respectively. In bisolute system, they were 74.46% and 60.20% for phenol and 2,4-DCP, respectively and degree of bioregeneration was corresponding to degree of hysteresis.

Cañizares, P.; De Lucas, A.; Rodríguez, L.; Villaseñor, J.

doi: 10.1080/09593332108618104pmid: N/A

A stationary laboratory scale sequencing batch reactor (SBR) process for enhanced biological phosphorus removal (EBPR) was developed, and the anaerobic uptake of different organic substrates was studied in batch experiments. The stationary process was developed using a synthetic wastewater composed of glucose and peptone, and the excess sludge removed from the process contained 6.5% phosphorus. Two series of batch anaerobic experiments were conducted, using glucose and peptone (Series 1) and acetate (Series 2) as carbon sources, and different COD concentrations. High phosphorus release rates, when acetate was used, could indicate the presence of a pre-fermentation step in the anaerobic phase of the A/O process. The maximum phosphorus release obtained under anaerobic conditions was 57% of the total phosphorus sludge content, that was reached using high COD concentrations. Metabolic mechanisms of COD uptake, apart from the known PAOs metabolism, were detected when glucose and peptone were used. These mechanisms were inhibited when acetate was used, probably because the microorganisms were not accustomed to acetate.

Shon, Jong-Sik; Lee, Sung-Ho; Kim, Gye-Nam; Kim, In-Tea; Shin, Hang-Sik

doi: 10.1080/09593332108618100pmid: N/A

This paper reports the effects of spent polyethylene (PE) addition on the bituminized waste forms with ash. In addition, leaching mechanism of those waste forms is evaluated through leach testing. The additive used for the experiment was spent PE generated from an agricultural polyethylene film. The bitumen used in sample preparation was straight-run distillation bitumen, a paving asphalt. The waste used for the experiment was a bottom ash generated from a hazardous wastes incinerator. Bituminized waste forms with PE contents of 5 wt% or more resulted in maintaining dimensional and mechanical stability. The compressive strength and softening point of bituminized waste forms are found to increase in proportion to the amount of spent PE. Leach testing also revealed that the principal leaching mechanism of metals (Cd, Cr, Cu, Pb) from bituminized waste forms is diffusion. Furthermore, it is demonstrated that additive PE of 5-10 wt% does not change leaching mechanism, and bituminized waste forms maintain a high leach resistance.

Kim, S.-O.; Moon, S.-H.; Kim, K.-W.

doi: 10.1080/09593332108618101pmid: N/A

Organic contamination in soil is a common problem at hazardous waste sites. This study investigates the application of enhanced electrokinetic soil processing to remediate soils contaminated with phenol (C6H5OH) and PCP (pentachlorophenol: Cl5C6OH). Electrokinetic soil remediation has high removal efficiency and time-effectiveness in low permeability soils such as clay. This experimental study examined the enhanced process of electrokinetically purging chemicals from saturated soils. Electrokinetic soil processing can significantly remove non-polar organic contaminants with electromigration, electroosmosis, diffusion and electrolysis of water. The removal efficiency is significantly influenced by applied voltage and current, type of purging solutions, soil pH, permeability and zeta potentials of soil. Depending on the original level or load of pollutants and the duration of the removal process, the removal efficiencies of phenol and PCP were higher than 85% over the duration of 4 days and mainly dependent on the electroosmotic flow.

Cox, H. H. J.; Deshusses, M. A.

doi: 10.1080/09593332108618102pmid: N/A

A new concept of periodically rotating biotrickling filters was developed for parallel operation of multiple bench scale biotrickling filters without the requirement for expensive equipment such as liquid recycle pumps and air flow regulation. The performance of 20 identically operated rotating biotrickling filters was reproducible with an average toluene elimination capacity of 79.4 g m−3 h−1 (s.d. = 5.7) at an empty bed residence time of 45 s and a toluene inlet gas phase concentration of 1.6 g m−3. At gas and liquid cocurrent operation, the toluene elimination capacity of rotating biotrickling filters was 20% higher than at countercurrent operation. This was probably caused by greater mass transfer limitation resulting from increased wetting of the biofilm during countercurrent operation. Performance versus load curves of rotating and of conventional biotrickling filters were comparable with non-zero order removal at toluene inlet concentrations lower than 2 g m−3. This multiple rotating biotrickling filters setup provides a new and inexpensive tool for comparative studies in biotrickling filtration for air pollution control.

Nudelman, N. S.; Rios, S. M.; Katusich, O.

doi: 10.1080/09593332108618105pmid: N/A

The interactions of crude oil, with soils having different clay and water contents were studied as a function of time, as a contribution to the understanding of the influence that sorption and desorption effects might have in the efficiency and effectiveness of the remediation techniques. Characteristic Patagonian soils have low amounts of organic matter, (usually less than 1%), and high clay contents; therefore, they are convenient media to study the influence of clay in sorption, avoiding interactions with organic matter. It was found that addition of clays to the soil changed the rate and extent of the interactions and favored the sorption; linear sorption uptake isotherms were observed. The partition coefficients, Kd, of the different samples are correlated with the clay and water contents in the soil, were the multiparametric equation obtained had a satisfactory predictive value. On the other hand, the data obtained with the different oil fractions are consistent with competitive interactions of the different types of chemical species for accessing to active sites. To evaluate the model, similar studies were carried out with simulated samples of known chemical composition. In spite of the complexity of the oil system, results obtained with the simulated samples were consistent with the sorption model. The parameters determined are useful for the design of remediation techniques.

Sahle-Demessie, E.; Richardson, T.

doi: 10.1080/09593332108618106pmid: N/A

Bench-scale supercritical fluid extraction (SFE) studies were performed on soil samples obtained from a Superfund site that is contaminated with high levels of p,p′-DDT, p,p′-DDD, p,p′-DDE, toxaphene and hexachlorocyclohexane. The effectiveness of supercritical fluid extraction was assessed using pure and modified CO2 as a solvent over a wide range of conditions. A 30-minute extraction at 30 MPa and 80°C was able to remove more than 98% of the contaminants and reduce the contaminated volume by a factor of 500. Solvent extraction and thermal desorption treatability studies were conducted on soil samples obtained from the same site to compare their performance with that of supercritical fluid extraction. A six-stage solvent extraction using methanol achieved 96 to 98% removal of the four contaminants, except for DDE which existed at low initial concentrations. The contaminated volume reduction was 40 to 50 times. Low temperature thermal desorption employed at 350°C for 30 minutes removed more than 98% for each contaminant except DDE. However, solvent extraction includes costly solvent regeneration and recycling steps, and thermal desorption generates air pollutants that require expensive particulate removal and gas stream cleaning. This study attempted to show that SFE can be as effective as other emerging technologies in removing contaminants from soils, and can reduce the contaminated volume by a large factor.

Brosillon, S.; Manero, M.-H.; Foussard, J. N

doi: 10.1080/09593330.2000.9618928pmid: N/A

In the present study, co-adsorption of gaseous n-heptane and acetone is studied. The adsorbent is a commercial hydrophobic zeolite. Breakthrough curves and isotherms are measured for three different acetone/heptane mixture ratios and for pure components. Zeolites showed a greater adsorption capacity for acetone alone than for heptane alone. For the mixtures, the majority component was the most adsorbed. Zeolites have a good selectivity for acetone even though acetone is more volatile than heptane. Specific adsorption sites are reserved for acetone adsorption and are not accessible to heptane. The polarity of a component leads to electrostatic interactions with cation exchange. On non-specific adsorption sites, acetone can be displaced by heptane, which is less volatile. Moreover, experiments show that selectivity depends on the ratio of the mixture. For co-adsorption of a mixture of polar and non-polar components, selectivity depends on relative polarity, mixture ratio, and boiling point.