Settleability of dry and wet weather flow samples from a combined sewer system was examined by settling column tests, in order to improve understanding of settling processes and obtain information for design of settling tanks. In fact, these tests mimic the actual settling processes and allow evaluating total suspended solids (TSS) removal by settling. Therefore, it is also possible to assess, indirectly, removals of other pollutants, such as heavy metals, which are generally transported by solid particles in sewage. Towards this end, dry and wet weather flow samples were collected in the Liguori Channel catchment and analyzed in the laboratory for Water Supply and Sewerage (Acquedotti e Fognature) of the University of Calabria for TSS concentrations according to the Standard Methods. The settleability study revealed that removals of TSS in dry weather samples (i.e., sanitary sewage) were greater than in wet weather samples (WW), using the same experimental procedures. In particular, 65% of TSS was removed in dry weather samples at a depth of 3 m for a detention time of 40 min; while in wet weather samples the comparable removal efficiency was less than 60%.

The effects of municipal sewage sludge applied on topsoil and understory vegetation (Molinia caerulea (L.) Moench) were studied in a maritime pine forest located in the South West of France (Landes of Gascogne). Understory response to sludge application is important as sludge addition to forest could increase competition with pine and affect herbivorous wildlife through incorporation of heavy metals in the food chain. The experiment was conducted in a young stand of maritime pines. The experimental design consisted of three 0.1-ha plots. One plot received composted sludge, one plot received liquid sludge, and one control plot received no sludge. Liquid sludge and composted sludge were applied on the basis of 3 tons dry matter sludge per hectare and per year. After 2 years of sludge application, we observed the following: (1) a significant increase in total concentrations of the following major and trace elements in the topsoil (layer 0–20 cm) [organic carbon (+140%), nitrogen (+140%), and lead (+80%)] and (2) no significant accumulation of trace elements in M. caerulea except nickel, which increased moderately (+40%) following application of composted sludge. These initial results need to be completed (1) by the assessment of long-term effects and dynamics of trace elements with additional applications of sludge and (2) by analyzing secondary understory species to determine if understory response to sludge application is more dependant on species than on soil parameters and sludge type.

Phosphorus (P) delivered by urban rainfall–runoff partitions and speciates during the transport process. This study examines transport and speciation of P in rainfall and runoff across 15 wet weather events from a paved source area dominated by biogenic loads and to a lesser degree, anthropogenic loads. The mean and median event-based source area total phosphorus is 3.6 and 3.5 mg/l, respectively. The mean and median event-based source area dissolved fraction (f d) are 0.31 and 0.32 illustrating that P is predominately bound to particulate matter fractions. The majority of events across the monitoring campaign produce a weak mass-limited transport of dissolved phosphorus (DP). With respect to the DP fraction in runoff (pH range of 6.4 to 8.6), the dominant species are orthophosphates (HPO4 −2 and H2PO4 −) which account for more than 90% of DP mass. The order of species predominance is consistently HPO4 −2 ≈ H2PO4 − >> CaHPO4 > MgHPO4. With rainfall pH ranging from 4.2 to 4.9 and a f d ≈ 1.0, H2PO4 − accounts for 95% to 99% of DP in rainfall. Despite the inherent variability of a large dataset (362 samples across 15 events) the speciation of DP is influenced primarily by pH, with a range from 4.2 (rainfall) up to 8.6 (runoff) that results in an order of magnitude change in P species concentration and determines the order between the dominant orthophosphate species. For this source area, the role of alkalinity, dissolved organic carbon and partitioning on DP speciation are minor compared to the influence of pH.

The kinetics and mechanism of methylene blue adsorption onto raw pine cone biomass (Pinus radiata) was investigated under various physicochemical parameters. The extent of the methylene blue dye adsorption increased with increases in initial dye concentration, contact time and solution pH but decreases with the amount of adsorbent, salt concentration and temperature of the system. Overall the kinetic studies showed that the methylene blue adsorption process followed pseudo-second-order kinetics among various kinetic models tested. The different kinetic parameters including rate constant, half-adsorption time and diffusion coefficient are determined at different physicochemical conditions. Equilibrium data were best represented by Langmuir isotherm among Langmuir and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine cone biomass was 109.89 mg/g at 30°C. The value of separation factor, R L, from Langmuir equation and Freundlich constant, n, both give an indication of favourable adsorption. Thermodynamic parameters such as standard Gibbs free energy (∆G 0), standard enthalpy (∆H 0), standard entropy (∆S 0) and the activation energy (A) were calculated. A single-stage batch absorber design for the methylene blue adsorption onto pine cone biomass has been presented based on the Langmuir isotherm model equation.

Polycyclic aromatic hydrocarbons and heavy metal (Pb, Cd, Cu, Zn, Hg, Fe, Co, Cr, Mo) contents were established in soil and plant samples collected in different areas of the railway junction Iława Główna, Poland. Soil and plant samples were collected in four functional parts of the junction, i.e. the loading ramp, main track within platform area, rolling stock cleaning bay and the railway siding. It was found that all the investigated areas were strongly contaminated with polycyclic aromatic hydrocarbons (PAHs). The PAH contamination of the soil was the highest in the railway siding and in the platform area (59,508 and 49,670 μg kg−1, respectively). In the loading ramp and cleaning bay, the PAH concentration in soil was lower but still relatively very high (17,948 and 15,376 μg kg−1, respectively). The contamination in the railway siding exceeded the average control level up to about 80 times. In the soil of all the investigated areas, four- and five-ring PAHs prevailed. The concentrations of PAHs were determined in four dominating species of plants found at the junction. The highest concentration was found in the aerial parts of Taraxacum officinale (22,492 μg kg−1) growing in the cleaning bay. The comparison of the soil contamination with PAHs in the investigated railway junction showed a very significant increase of the PAHs level since 1995. It was found that the heavy metal contamination was also very high. Pb, Zn, Hg and Cd were established at the highest levels in the railway siding area, whereas Fe concentration was the highest in the platform area. A significant increase in mercury content was observed in the cleaning bay area. The investigations proved very significant increase of contamination with PAHs and similar heavy metals contamination in comparison with the concentration determined in the same areas 13 years ago.

This study investigated the storage of nitrogen (N) and phosphorus (P) in the biomass, bed sediments and water column of representative reaches of a sub-tropical river, the upper Brisbane River (UBR), Queensland, Australia, and contrasted instream storage with total wet season exports. In reaches which contained accumulated fine sediments, more than 87% of total P and between 50% and 92% of total N were stored in the surface sediments. The lower proportion of N in sediment at some sites was attributed to substantial differences in the N/P ratios of sediments and macrophytes. At one site, the riverbed was dominated by cobbles and boulders and total nutrient stocks were comparatively low and dominated by the biomass. In reaches with a narrow channel and intact riparian cover, biomass N and P were stored predominately in leaf litter, while in wider unshaded reaches, macrophytes dominated. Total instream storage in the mid to lower reaches of the UBR was ∼50.9 T for N and ∼18.1 T for P. This was considerably higher than total wet season N (∼15.6 T) and P (∼2.7 T) exports from the UBR. The first flow event in the river after a prolonged period of no flow resulted in the export of free-floating, emergent species Azolla. The estimated biomass of Azolla in the mid to lower reaches of the river was equivalent to approximately 24% and 9% of the total N and P flux, indicating that this may be a significant, previously unaccounted for, source at peak flow.

A constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In the field monitoring, ammonium (NH ₄ ⁺ ) decreased from 4.6 to 1.7 mg L⁻¹, nitrate (NO ₃ ⁻ ) decreased from 6.8 to 5.3 mg L⁻¹, total N (TN) decreased from 14.6 to 10.1 mg L⁻¹, and total P (TP) decreased from 1.6 to 1.1 mg L⁻¹. Average removal efficiencies (loading basis) for NO ₃ ⁻ , NH ₄ ⁺ , TN, and TP were over 70%. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH ₄ ⁺ . Results from mesocosm experiments indicated that NH ₄ ⁺ was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO ₃ ⁻ was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2-4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH ₄ ⁺ and P can be maximized in the pond while NO ₃ ⁻ requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal of N and P from effluents of a secondary wastewater treatment plant.

Due to the inherent differences in bioavailability and transport properties of particulate and dissolved mercury (HgP and HgD), it is important to understand the processes by which each is mobilized from soil to stream. Currently, there is a paucity of HgP data in the literature despite the fact that it can be the dominant fraction in some systems. We analyzed HgP in conjunction with volatile solids (VS, an estimate of organic content) and total suspended solids (TSS) and investigated the viability of using turbidity as a surrogate measure of HgP. Samples were collected for flow conditions ranging from 72 to 8,223 L s−1 during October 2009 through March 2010 in a 10.5-km2 forested headwater catchment. Total Hg concentrations ranged from 0.28 to 49.60 ng L−1, with the relative amount of HgP increasing with discharge from approximately 40% to 97%. Storm dynamics of HgP and HgD were not consistent, indicating unique controls on the export of each fraction. During high-flow events, HgP was consistently higher on the rising limb of the hydrograph compared with the receding limb for a range of discharge events, with this hysteresis contributing to a degraded relationship between HgP and streamflow. Overall, HgP was strongly positively correlated with VS (r 2 = 0.97), confirming the known association with organic carbon. Due to a consistent organic fraction of the suspended solids (34 ± 6%), HgP was also well correlated with TSS (r 2 = 0.95), with an average of 0.10 ng of HgP per milligram of TSS in this system. Stream turbidity measured with an in situ sonde also had a strong correlation with TSS (r 2 = 0.91), enabling commutative association with VS (r 2 = 0.86) and HgP (r 2 = 0.76). Turbidity can explain more than twice the temporal variance in HgP concentrations (n = 50) compared with discharge (r 2 = 0.76 versus 0.36), which leads to improved monitoring of HgP dynamics and quantification of mass fluxes.

Biosorption has potential to be an economical colour removal technology. As such, the colour removal potential of inactivated Aspergillus niger biomass was investigated for the treatment of activated sludge-treated pulp mill effluent from a northern bleached softwood kraft mill. Biomass pretreatment methods, effects of initial pH of the effluent and preparative biomass washing methods were examined. The most effective pretreatment method was found to be simple autoclaving of the biomass and this approach was applied in subsequent kinetic and isotherm batch studies. It was also found that the pH of the wastewater prior to addition of the biomass affected the biosorption rate and the solubility of chromophores in pulp mill effluent. The results also indicated that biomass washing methods reduced the quantity of organic matter leached from the fungal biomass during application. The kinetic study revealed that colour removal by biosorption occurred most readily in the first 8 h and could be described adequately by both the Lagergren and Ho et al. models. The maximum colour removal was over 900 TCU, with a biomass dose of about 20 g/L. The isotherm study data were fitted with the BET isotherm model. The results indicated that adsorption occurred in a multi-layer fashion and that physical adsorption was the main mechanism contributing to the biosorption. Therefore, dead A. niger biomass was concluded to be a promising alternative for colour removal from pulp mill effluent.

Application of one-dimensional transport considering multiple member of decay chain in a single rock fracture has been studied. Input sources for constant, pulse, impulse, Heaviside, and exponential decay have been used to demonstrate the suitability of relevant solutions. It shows that the breakthrough curves of dimensionless concentration for the three-member decay chain for Np-237 and the seven-member chain for Cm-246 can be well presented in the temporal and spatial domains. The analytical solutions of this study can clearly demonstrate the general form of contaminant transport with complete multiple-member decay chain in one-dimensional fractured or porous media of arbitrary analytical input sources without considering the matrix diffusion, which the conceptual model provides an alternative type to demonstrate the fate of radionuclide transport in the geosphere. The solutions are conservatively used to support the performance assessment for disposal site of radioactive waste. An application to a hybrid test site for the final disposal of spent nuclear fuel is newly demonstrated. Proposed solution to simulate the transport of nuclides in the one-dimensional pathway of host rock becomes feasible, so that the simulation and prediction of radionuclide transport of fractured media existing in geosphere can be conservatively performed in the future.