Inorganic Micropollutants Research Articles

Spatial and temporal trends of target organic and inorganic micropollutants in Lake Maggiore and Lake Lugano (Italian-Swiss water bodies): contamination in sediments and biota

DDx, PCBs, PBDEs, Hg, and As contamination in sediments and aquatic organisms of different trophic levels (zooplankton, mussel, fish) were analyzed in Lake Maggiore and Lake Lugano, two large deep perialpine lakes. In the period 2001–2015, we analyzed the spatial and temporal trends of the considered pollutants to detect potential contamination sources and to compare concentrations with Sediment Quality Guidelines (SQGs) or existing Quality Standards (QSs). DDx and Hg contamination deriving from past industrial activities in the Pallanza Basin still exceeded SQGs in sediments and QSs in fish, with potential risks for the ecosystem. Banned in Europe in 1985, PCBs showed low residual values, while recent PBDE peaks resulted in the exceedance of the QSs for biota in both lakes, probably due to current industrial activities. Arsenic mainly derives from geochemical origin. The analysis of the biomagnification of toxicants in a pelagic food chain in Lake Maggiore (zooplankton–fish) according to a stable isotope approach is also presented, according to both the Trophic Magnification Factor and the Trophic Level-adjusted BioMagnification Factor: the importance of seasonality and a Hg > DDx ≈ PBDEs biomagnification capacity were observed. Low PCB bioaccumulation was detected in biota, probably because equilibrium was not reached yet in young fish.

Biodegradation of fluoranthene by a newly isolated strain of Bacillus stratosphericus from Mediterranean seawater of the Sfax fishing harbour, Tunisia.

A physico-chemical characterization of seawater taken from the fishing harbour of Sfax, Tunisia, revealed a contamination by organic and inorganic micropollutants. An aerobic marine halotolerant Bacillus stratosphericus strain FLU5 was isolated after enrichment on fluoranthene, a persistent and toxic polycyclic aromatic hydrocarbon (PAH). GC-MS analyses showed that strain FLU5 was capable of degrading almost 45% of fluoranthene (100mgl(-1)), without yeast extract added, after 30days of incubation at 30gl(-1) NaCl and 37°C. In addition, the isolate FLU5 showed a remarkable capacity to grow on a wide range of aliphatic, aromatic and complex hydrocarbons. This strain could also synthesize a biosurfactant which was capable of reducing the surface tension of the cell-free medium, during the growth on fluoranthene. The biodegradative abilities of PAHs are promising and can be used to perform the bioremediation strategies of seawaters and marine sediments contaminated by hydrocarbons.

Kinetic study of copper adsorption onto Moroccan Illitic and kaolinite clay

In order to optimize and reduce the rate of inorganic micropollutants rejected by various metal installations, according to wastewater treatment standards and environmental protection, we proceeded by studying the adsorption of heavy metals such as copper by using the Illitic and Kaolinite Clay from Moroccan (IKCM) of El Oulja-Sale region. We are interested in the analysis of the physicochemical parameters influencing the removal of heavy metals (time effect, mass effect absorbent, concentration of initial copper solutions effect, stirring rate effect and the solution’s pH). The results of this study was produced by the characterization technique of X-Ray Diffraction (XRD), the Atomic Adsorption Spectroscopy (AAS) and linear forms Langmuir isotherm and Frendlich models which show that the binding and removal copper by this clay is fast with increasing parameters mentioned previously.

Assessing potential modifications to the activated sludge process to improve simultaneous removal of a diverse range of micropollutants

It is proposed that wastewater treatment facilities meet legislated discharge limits for a range of micropollutants. However, the heterogeneity of these micropollutants in wastewaters make removal difficult to predict since their chemistry is so diverse. In this study, a range of organic and inorganic micropollutants known to be preferentially removed via different mechanisms were selected to challenge the activated sludge process (ASP) and determine its potential to achieve simultaneous micropollutant removal. At a fixed hydraulic retention time (HRT) of 8 h, the influence of an increase in solids retention time (SRT) on removal was evaluated. Maximum achievable micropollutant removal was recorded for all chemicals (estrogens, nonylphenolics and metals) at the highest SRT studied (27 days). Also, optimisation of HRT by extension to 24 h further augmented organic biodegradation. Most notable was the enhancement in removal of the considerably recalcitrant synthetic estrogen 17α-ethinylestradiol which increased to 65 ± 19%. Regression analysis indicates that this enhanced micropollutant behaviour is ostensibly related to the concomitant reduction in food: microorganism ratio. Interestingly, extended HRT also initiated nonylphenol biodegradation which has not been consistently observed previously in real wastewaters. However, extending HRT increased the solubilisation of particulate bound metals, increasing effluent aqueous metals concentrations (i.e., 0.45 μm filtered) by >100%. This is significant as only the aqueous metal phase is to be considered for environmental compliance. Consequently, identification of an optimum process condition for generic micropollutant removal is expected to favour a more integrated approach where upstream process unit optimisation (i.e., primary sedimentation) is demanded to reduce loading of the particle bound metal phase onto the ASP, thereby enabling longer HRT in the ASP to be considered for optimum removal of organic micropollutants.

Occurrence of Micro-pollutants in a Soil–Radish System Irrigated with Several Types of Treated Domestic Wastewater

During this study, the effect of applying several types of treated domestic wastewater on the translocation and accumulation of organic and inorganic micropollutants in soil and radish plants (Raphanus sativus L.) was examined. Primary (PTW), secondary (STW) and tertiary (TTW) treated wastewater as well as tap water (TW) were used for the irrigation of radish plants for a period (transplantating and harvesting) of 67 days. Higher concentrations of polycyclic aromatic hydrocarbons (PAHs) were observed in soils irrigated with PTW. The concentration of PAHs in radish roots ranged between 107.6 ± 12.1 μg/kg for plants irrigated with TTW and 124.1 ± 17.7 μg/kg for plants irrigated with PTW. The root concentration factors (RCFs) expressed as the ratio of PAH concentration in the root mass (dry weight) to the residual concentration in the soil varied from 1.6 to 1.9 indicating a higher accumulation of PAHs in the edible part of radishes than soil. Heavy metals were not detected in the wastewaters utilised and, as a result, no accumulation was found in either the soil or plants in comparison with tap water. RCFs for heavy metals were calculated between 0.91 and 0.99, 0.49 and 0.66, 0.004 and 0.005 for Cu, Zn and Ni, respectively. The results showed that radishes have the ability to concentrate PAHs when they are present in the wastewater and this could have associated health risks.

Environmental magnetic studies on surface sediments: a proxy for metal and hydrocarbon contamination

Visakhapatnam is one of the major port cities, and it is developed into a hub of many large- and medium-scale industries. Due to growing industrialization and urbanization, coast is vulnerable to both organic and inorganic micro-pollutants. Twenty-five surface sediments were collected along the Visakhapatnam coast for the measurement of texture size, petroleum hydrocarbons, trace metals and environmental magnetic parameters. The percentage of coarser particles was more in the northern region, whereas the percentage of fine particles was increased toward south. Elevated levels of petroleum hydrocarbons and trace metals were attributed due to marine and land-based sources, in particular, those were due to shipping activities, treated and partially treated sewage and industrial wastes. The concentrations of trace metals, petroleum hydrocarbons and magnetic minerals were decreased from nearshore to seaward. Our results revealed that the magnetic mineralogy is dominated by magnetite with a small proportion of hematite, and the grain size of magnetic minerals was in the range of pseudo-single domain to multidomain nature with detrital origin. From the principal component analysis, the magnetic concentration and mineralogy-dependent parameters co-vary with the heavy metal and PHC concentrations, suggesting that the inputs of magnetic minerals, petroleum hydrocarbons and heavy metals in the Visakhapatnam shelf sediments were derived from the same anthropogenic sources. Thus, the large magnetic dataset can be used to reduce the number of chemical analysis; hence, environmental magnetic parameters were used as a proxy for both organic and inorganic micro-pollutants.

Phenolic Compounds: Health Effects and Its Removal From Aqueous Environments by Low Cost Adsorbents

Implication for health policy/practice/research/medical education: The content of this article is useful for environmental health managers and also for industrial waste managers for efficient treatment of industrial wastewaters. Copyright © 2013, Health Promotion Research Center. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http:// creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Phenols are natural products originated by various plants and animals decomposition. Also, phenolic compounds, as a class of organic materials, have a similar structure to the more common pesticides which are commonly resistant to biological degradation. In addition, phenol is one of the most general pollutants in effluents discharged from diverse industries producing various products including resins, plastics, adhesives, iron, steel, aluminum, leather, etc. Additionally, phenol is used as a solvent, as an antiseptic and as an additive in disinfectants (1, 2). These industries are distributed in wide area, which result in severe environmental troubles because of their toxicity low biodegradability and their ability to build up potential in plants and tissues, such as fish which live in the lakes and streams polluted with phenolic compounds have a revolting astonishing flavor and very bad smell. Consequently, the effluents containing phenol and its derivatives must be treated prior to their release into water resources. Furthermore, phenol is a combustible compound that is extremely soluble in water, oil and numerous organic solvents. It is characterized by a representative sharp sweet, medical, or tar like smell (3). In addition, in the presence of chlorine in water, phenol forms chlorophenol, which has a medical flavor, which is completely manifest and unpleasant. Also, phenol is a troublesome contaminant that contributes to off flavors in food processing waters. Presence of phenol in water resources can result in the reduction of water quality, decease of aquatic organisms and also prohibition of the common acts of biological community (4). Almost the entire phenols are toxic and some are known as carcinogen for human. These compounds are incorporated in the food chain and cause significant environmental troubles. Owing to their toxic effects, including permeabilization of cellular and cytoplasmic coagulation and also irritation to skin, phenolic compounds can injure sensitive cells and consequently cause profound health and environmental issues (5, 6). On the other hand, acute poisoning can cause strict gastrointestinal disturbances, kidney malfunction, and circulatory system failure and also lung edema. Deadly doses can be absorbed through the skin. Key organs injured by chronic exposure to phenol consist of spleen, pancreas and kidneys (7). Therefore, phenol and its compounds are grouped as priority pollutants by the United States of environmental protection agency (USEPA), which take the 11th place under the 129 chemicals with a discharge limit of lower to 1 mg/L in the treated effluent in order to human health protection from the possible toxic effects caused by exposure to phenol (8). In Iran, a maximum phenol level of 1.0 mg/L is permitted in wastewater for discharge to surface water resources by the Institute of Standard and Industrial Research of Iran (ISIRI). Wastewaters containing phenols and other toxic compounds require careful treatment before release into the receiving water sources. Dutta et al. (9) classified the treatment processes of phenolic effluents into two main categories: destructive process such as destructive oxidation with O3, H2O2, or manganese oxides, and recuperative processes such as adsorption and membrane separation. Adsorption process is presently being used broadly for organic and inorganic micropollutants removal from aqueous environments (3). This procedure is the easiest, the fastest, the most efficient and cost-effective option for removal of phenolic compounds. Among different materials, activated carbon has high affinity to phenolic compounds. Nevertheless, the high cost of activated carbon has stimulated interest in investigating the possibility of rc h f SI D

Application of membrane processes in drinking water treatment–state of art

Membrane technology is widely accepted as a means of producing various qualities of water from surface water, well water, brackish water and seawater. In the treatment of water for drinking purposes first of all pressure-driven membrane techniques are used. The choice of the suitable membrane process depends on the size of the removed contaminants and admixtures from the water. Desalination of seawater and brackish groundwater is often the way to obtaining drinking water. Significant improvements in technology and design of reverse osmosis, the availability of alternative energy sources, the possibility of pretreatment and applied materials have caused the process to become environmentally-friendly source of fresh water in many regions of the world, particularly in those where their sources are limited. Nanofiltration and to some extent the reverse osmosis are the methods of water softening, as well as to remove disinfection by-products precursors and micropollutants. To remove inorganic micro-pollutants ...

Toxicity removal efficiency of decentralised sequencing batch reactor and ultra-filtration membrane bioreactors

As a consequence of the Water Framework Directive and Marine Strategy Framework Directive, there is now more focus on discharges from wastewater treatment plants both to transitional and marine-coastal waters. The constraint to encourage sustainable water policy to prevent water deterioration and reduce or stop discharges has entailed new requirements for existing wastewater treatment plants in the form of advanced wastewater treatment technologies as further suggested by the Integrated Pollution and Prevention Control Bureau. A whole toolbox of physico-chemical and ecotoxicological parameters to investigate commercial and mixed domestic and industrial discharges was considered to check the efficiency of an Activated-Sludge Sequencing Batch Reactor (AS-SBR) and two Ultra-Filtration Membrane Biological Reactors (UF-MBRs) on a small scale decentralised basis. All discharges were conveyed into Venice lagoon (Italy), one of the widest impacted Mediterranean transitional environment. The UF-MBRs were able to provide good quality effluents potentially suitable for non-potable reuse, as well as reducing specific inorganic micro-pollutants concentration ( e.g. metals). Conversely, the AS-SBR showed unpredictable and discontinuous removal abilities.

The fate of metals in wastewater treated by the activated sludge process and membrane bioreactors: A brief review

The fate of metals in wastewater treatment by the conventional activated sludge process (ASP) and membrane bioreactors (MBRs) is reviewed. The review outlines the environmental and health impacts of metals, but focuses primarily on data reported for removal of toxic metals, and some other high-profile inorganic micropollutants such as aluminium and arsenic, by wastewater treatment processes. Information from pilot and full scale plants is included, with corroboratory reports from bench-scale tests. General trends in removal across different metals are considered, along with the impact of the key process operating determinant of solids retention time. It is concluded that the only consistent trend in metals removal is that it is most effectively achieved through efficient solids separation, and that this represents the primary advantage offered by the MBR. As such, MBRs achieve averaged metals removals which are consistently but not dramatically higher than the ranges reported by the ASP: 64-92% vs. 51-87%, with no more than a 55% decrease on average in effluent concentration. The slightly greater removal attained is attributable to the additional suspended solids retention attained by the membrane process. In either case, further removal of metals would demand a tertiary process for removal of the dissolved material.

Lysosomal responses and metallothionein induction in the blue mussel Mytilus edulis from the south-west coast of Iceland

It has recently been emphasized that high levels of inorganic and organic micropollutants (particularly organometals, POPs and PAHs) may be present in coastal waters at high latitudes, stressing the need to evaluate the effects of contaminants on marine organisms from sub-arctic zones. With this aim, specimens of the blue mussel Mytilus edulis were sampled in polluted and reference areas along the south-west coast of Iceland in July 2004. Samples were collected from the intertidal zone at three sites in Reykjavik harbour which are differently exposed to contaminants, and at three reference coastal sites, two located along the Reykjanes Peninsula and the third one on the northern part of Hvalfjordur fiord. Lipofuscin content, neutral lipid accumulation and lysosomal enlargement were evaluated in digestive cells from cryostat sections of the mussel hepatopancreas, and quantified by automated image analysis. Metallothionein induction was also determined in the same tissue. Results indicate that mussels from the inner part of Reykjavik harbour, which is the most sheltered and most influenced by extensive shipping traffic, were the worst affected, with the highest values in neutral lipids, lipofuscin and lysosomal swelling. At the other two harbour sites, mussels exhibited lower values, similar to those observed in organisms collected in Hvalfjordur fiord and in bay of Osar. Mussels from Kuagerdi had the lowest values.

The Effects of Scaling and Model Complexity in Simulating the Transport of Inorganic Micropollutants in a Lowland River Reach

Abstract A hypothesis stating that more complex descriptions of processes in models simulate reality better (less error) but with more unreliable predictability (more sensitivity) is tested using a river water quality model. This hypothesis was extended stating that applying the model on a domain of smaller scale requires greater complexity to capture the same accuracy as in large-scale model applications which, however, leads to increased model sensitivity. The sediment and pollutant transport model TOXI, a module in the WASP5 package, was applied to two case studies of different scale: a 90-km course of the 5th order (sensu Strahler 1952) lower Saale river, Germany (large scale), and the lock-and-weir system at Calbe (small scale) situated on the same river course. A sensitivity analysis of several parameters relating to the physical and chemical transport processes of suspended solids, chloride, arsenic, iron and zinc shows that the coefficient, which partitions the total heavy metal mass into its dissolved and sorbed fraction, is a very sensitive parameter. Hence, the complexity of the sorptive process was varied to test the hypotheses.

Spatial analysis in ecological risk assessment: Pollutant bioaccumulation in clams Tapes philipinarum in the Venetian lagoon (Italy)

Exposure characterization is a central step in Ecological Risk Assessment (ERA). Exposure level is a function of the spatial factors linking contaminants and receptors, yet exposure estimation models are traditionally non-spatial. Non-spatial models are prone to the adverse effects of spatial dependence: inflated variance and biased inferential procedures, which can result in unreliable and potentially misleading models. Such negative effects can be amended by spatial regression modelling: we propose an integration of geostatistics and multivariate spatial regression to compute efficient spatial regression parameters and to characterize exposure at under-sampled locations. The method is applied to estimate bioaccumulation models of organic and inorganic micropollutants in the tissues of the clam Tapes philipinarum. The models link bioaccumulation of micropollutants in clam tissue to a set of environmental variables sampled in the lagoon sediment. The Venetian lagoon case study exemplifies the problem of multiple variables sampled at different locations or spatial units: we propose and test an effective solution to this common and serious problem in environmental as well as socio-economic multivariate analysis.

Removal of micropollutants by NF/RO membranes

Organic and inorganic micropollutants are rejected by high-pressure membranes, nanofiltration (NF) and reverse osmosis (RO), primarily as a consequence of solute–membrane interactions. These interactions include steric and electrostatic effects that depend on compound properties (e.g., molecular weight (MW) and ionic charge) and membrane properties (e.g., molecular weight cutoff (MWCO) and surface charge (zeta potential)), with the added influence of membrane operating conditions (e.g., recovery). This paper summarizes the rejection trends by several NF and RO membranes for a wide range of organic micropollutants based on hydrophobicity/hydrophilicity (octanol-water partition coefficient, KOW) and charge (neutral or negative), and a more narrow range of inorganic micropollutants in the form of oxyanions (chromate, arsenate and perchlorate) of varying MW and charge. While RO provided greater rejections of micropollutants than NF, observed NF rejections were, in many cases, significant. For oxyanions, rejection was mainly influenced by ionic charge and MW. RO properties generally had little influence while MWCO and zeta potential were both significantly influential for NF. For organic micropollutants, with exception of RO versus NF classifications, membrane properties were less influential than compound properties with greater rejections generally observed with increasing MW, KOW, and (negative) charge.

Atmospheric bulk deposition to the lagoon of Venice: Part I. Fluxes of metals, nutrients and organic contaminants

First available data on atmospheric fall-out were provided by sampling monthly bulk depositions in four sites inside the Lagoon of Venice (550 km 2). Sampling was carried out monthly during the period July 1998–July 1999, in one site near an industrial area (Porto Marghera; site D), another site in the city of Venice (site A), and the remaining two in the southern- and northernmost ends of the Lagoon (Valle Figheri, site C; Valle Dogà site B). The following determinations were carried out for each samples: pH, conductivity, grain-size, particulate load, and dissolved nutrients (N, P). Samples were then subdivided into soluble and insoluble fractions, and Al, Ca, Na, K, Mg, Si, Mn, Fe, Zn, Ni, Cr, Cu, Pb, Cd, As, Hg, Ti, V, S, P, Se and Sb were analysed on both fractions. Total organic micropollutants (PAH, PCB, HCB, DDT, PCDD/F) were measured. As regards particle size distribution, there was great variability among sampling sites. The percentage of the ≤ 2 μm grain-size fraction was higher in the southern and northern ends of the Lagoon. Small differences were found among sites for major elements, whereas higher variability was observed for inorganic and organic micropollutants, with standard deviations between 20% and 60% of the fluxes measured. Major differences in annual fluxes between the most polluted sites (mostly D and A) and background (site B) were seen for Cd (0.26 vs. 0.06 mg m − 2 year − 1), Hg (41 vs. 15 μg m − 2 year − 1), PCB (∼ 2500 vs. ∼ 500 ng m − 2 year − 1) and HCB (∼ 8000 vs. ∼ 1000 ng m − 2 year − 1). Comparisons with previous data, collected in the periods 1993–1994 and 1995–1997, were only available for a few trace metals. A definite decline in the annual Pb flux in the city of Venice was detected, from 18 to 13 mg m − 2 in 1996/1997 and 1995/1996 respectively, to ∼ 5 mg m − 2 in the present study. Total annual deposition was calculated by means of two different methods, which gave very similar results: (i) the mean value of deposition in the four sites was multiplied by lagoon area (550 km 2); (ii) the monthly rain isopleths were combined to normalize deposition values. The figures are: 15–34 kg of Hg and Sb, ∼ 200 kg of As, ∼ 100 kg of Cd and PAH, 0.7–1.3 tons of Cr, Ni and V, more than 2 tons of Cu and Pb, 17 of Zn, 55 of total P, ∼ 200 of Al, and 3900 of DIN. Total fluxes of organics inside the lagoon were: PAH ∼ 100 kg; HCB ∼ 1 kg; DDT ∼ 0.4 kg. PCB and PCDD/F fluxes were ∼ 500 g and ∼ 10 g, corresponding respectively to 0.1 and 0.4 g I-TE. The correlations between fluxes of inorganic micropollutants and grain-size were significant. Multivariate statistical analysis was applied to investigate more accurately relationships between the insoluble and dissolved fractions of inorganic micropollutants and grain-size fractions. In particular, significant correlations were highlighted between the dissolved fraction of As and the ≤ 1 μm particle size fraction. Relations between levels of ΣPCDDF, ΣPCDD, PCB and PAH congeners and grain-size revealed significant correlation coefficients for the remote sites (B, C), and none in the urban and industrial sites (A, D). In particular, significant correlations were highlighted between ΣPCDDF, ΣPCDD and particle size fraction ≤ 2 μm, and between benzo( a)pyrene and PCB 167 and particle size fraction 4–8 μm.

Chemical and microbial characterization of indigenous topsoil and mosses in green urban areas of Rome

Sources of potential contamination for an urban soil are basically due to atmospheric fallout of pollutants produced by domestic heating system and vehicular traffic. Taking into account the recent use of catalytic converters, persistent inorganic micropollutants like Platinum Group Elements (PGEs) must be added. The present research is based upon the use of natural matrices (indigenous mosses and topsoil) to study the distribution of concentration of the following inorganic pollutants: Al, Cd, Cr, Cu, Hg, Ni, Pb, V, Zn and PGEs (Pt, Pd, Rh). Determination of such element has been performed by different instrumental spectroscopy techniques, in particular HR-ICP-MS for PGEs and ICP-AES and ETAAS for the other elements. Microbial parameter such as Actinomycetes, Moulds and Total Bacterial Count at 22 °C have been surveyed in mosses as well, due to their high sensitivity to low loads of pollutants. Urban areas in the city of Rome monitored during investigation have been Villa Borghese, Villa Ada and Villa Doria Pamphili. Eleven stations have been set up altogether. Two more spots (Villa Celimontana and National Institute of Health's gardens) have been investigated to get a more complete survey of the entire area. The aim of this study is to provide data set on levels of inorganic traffic-related micropollutants present in urban soil, supporting the use of indigenous mosses as passive biomonitors, and compare such data with those from other Italian cities. An estimation of time-depending changing of PGEs concentration in natural matrices is provided as well.

Quality of dredged material in the river Seine basin (France). II. Micropollutants

Dredging rivers is needed to ensure safe navigable waters, rivers and waterways. To anticipate the management of dredged materials in the case of the river Seine basin, the quality of the sediments in the river is checked every 3 years before dredging operations. The river Seine Basin is heavily submitted to pollution pressure from nearby industrial activities and urban expansion of Paris and its region. Here, the micropollutant content of the sediment sampled in 1996, 1999 and 2000 before dredging is discussed compared to regulatory standards. The results indicate that most of the sediment samples from the river Seine basin are lightly to moderately contaminated with organic and inorganic micropollutants (heavy metals, PAH, PCB), which makes the management after dredging easier. This pollution is strongly correlated with the organic matter content and to the fine fraction (<50 μm) of the sediment. These results can lead to other management options than the ones already used in the river Seine basin: (1) dumping of lightly to moderately polluted sediments in quarries; and (2) physical treatment (sieving, hydrocycloning) of contaminated sediments issued from ‘hot spots’.

Leaching of Nutrients and Trace Metals from Aerosol Samples; A Comparison Between A Re-Circulation and an Ultrasound System

As part of a project investigating the air-water exchange of nutrients and inorganic micropollutants to the North Sea, the atmospheric deposition of nutrients and trace metals in their different compositions and via various pathways was investigated. Intensive sampling campaigns were organised on the research vessel Belgica (ns 21/98 campaign from September 28 to October 1, 1998 and ns 10/99 campaign from April 19 to 23, 1999), at a sampling station near the Belgian coast (Knokke-Heist) and at the University campus of Antwerp. Simulation work and remobilisation experiments were carried out to obtain a general view of the kinetics of solubilisation of the constituents under investigation. Sample treatment requires a leaching system with a quantitative recovery of the species of interest in the leaching solution within a reasonably short period of time (30 min). For this reason, a re-circulation leaching system was developed, tested, optimised and compared with a more accepted ultrasound leaching method.

Comparison of polyelectrolytes applied in drinking water treatment

The applicability of an inorganic, polyaluminium-type flocculent was tested comparing to polyacrylamides — an organic-type flocculent — used in the drinking water treatment process. The efficiency of this inorganic flocculent in the removal of suspended solids and also in minimizing the residual concentrations of the dissolved organic and inorganic micro-pollutants was checked in the case of purifying filter backwash water. Experimental data showed the advantage of the inorganic flocculent applying procedure as a part of recent water treatment technology. The applied polyaluminium-salt was economically competitive, improved the process stability and also ensured good water quality parameters.

Composting of sewage sludge in a rotating vessel

Composting of sewage sludge can enhance its quality and suitability for agricultural use. In this work the optimal conditions for composting sewage sludge of small domestic wastewater treatment plants in a rotating vessel with the aim of sanitary safety were investigated. An intensive control programme with regard to viruses, bacteria and parasites was carried out that showed that the hygienic quality was satisfactory. A second aspect was the investigation of a possible reduction of hazardous organic and inorganic pollutants. The amount of inorganic micropollutants was low and did not change based on inorganic content. Based on inorganic residues, losses of 15.7% of the AOX and 25% of the EOX could be found. Relatively high decreasing rates of detergent concentrations could be measured. Only 31.1% of the original load of anionic detergents (measured as MBAS), 38.7% of the cationic and 57.4% of the non-ionic detergents could be detected in the end material. For PAH concentration reduction between 31.5% of fluoranthene and 90.6% benzo(a)pyrene can be reported. All values are based on the inorganic residues. The quality of the resulting compost showed in the plant test a growth rate which qualified the compost to be used to increase soil quality.