The lability and mobility of Zn(II)-, Cd(II)-, Pb(II)-, and Cu(II)-humic acid complexes were studied using diffusive gradients in thin films (DGT). A unique feature of this research was (1) the use of DGTs with diffusive layer thicknesses ranging from 0.4 to 2.0 mm to study lability and mobility of Zn(II)-, Cd(II)-, Pb(II)-, and Cu(II)-humic acid complexes, combined with (2) the application of a competing ligand exchange (CLE) method using Chelex 100, the same chelating resin that is used in DGT, to study the kinetic speciation. The CLE experiments were run immediately after the completion of the DGT experiments, thereby allowing effects of the competing ligand to be separated from the effects introduced by the use of the polyacrylamide gel that is used in DGT. The results indicate that Zn(II) and Cd(II) tend to form more labile and more mobile complexes with humic acid than Pb(II) or Cu(II). The dissociation rate constants of Zn(II), Cd(II), and Pb(II) were found to increase with the ionic potential of the metal, suggesting that the binding between some trace metals and humic acid has a significant covalent component. Furthermore, the results suggest that the Eigen mechanism may not be strictly obeyed for metals such as Cu(II) which have high rate constants of water exchange, k w. Consequently, the markedly slow kinetics of Cu(II)-HA species suggests that the usual equilibrium assumption may not be valid in freshwaters.

A submerged membrane bioreactor (MBR) was used to treat two types of petrochemical wastewater: olefin process wastewater and total petrochemical wastewater. Various operational MBR conditions, such as influent pH and hydraulic retention time (HRT), were tested while these wastewaters were treated. The MBR treatment of olefin process wastewater reduced chemical oxygen demand (COD) and total organic carbon (TOC) by around 90% in both cases, and more than 90% of the suspended solids (SS) were removed. When MBR was used, the reduction in COD and TOC was also high for the total petrochemical wastewater, and was compared with the reduction obtained when the conventional activated sludge treatment plant was used (CASP). However, MBR effluent wastewaters showed high conductivity so for some reuse purposes subsequent reverse osmosis (RO) treatment would be needed. We characterized the MBR influent and MBR effluent wastewaters using a sequential solid phase extraction (SSPE) followed by gas chromatography-mass spectrometry (GC-MS) analyses. The main compounds that were tentatively identified were hydrocarbons, alkyl benzenes, phenols, acidic acids and esters, almost all of which could be partially or completely removed by MBR treatment.

In this study, a high-rate fibre filter was used as a pre-treatment to stormwater in conjunction with in-line flocculation. The effect of operating the fibre filter with different packing densities (105, 115 and 125 kg/m³) and filtration velocities (20, 40, 60 m/h) with and without in-line flocculation was investigated. In-line flocculation was provided using 5, 10 and 15 mg/L of ferric chloride (FeCl₃·6H₂O). The filter performance was studied in terms of pressure drop (ΔP), solids removal efficiency, heavy metals (total) removal efficiency and total organic carbon (TOC) removal efficiency. It is found that the use of in-line flocculation at a dose of 15 mg/L improved the performance of fibre filter as measured by turbidity removal (95%), total suspended solids reduction (98%), colour removal efficiency (99%), TOC removal (reduced by 30-40 %) and total coliform removal (93%). The modified fouling index reduced from 750-950 to 12 s/L² proving that fibre filter can be an excellent pre-treatment to membrane filtration that may be consider as post-treatment. The removal efficiency of heavy metal was variable as their concentration in raw water was small. Even though the concentration of some of these metals such as iron, aluminium, copper and zinc were reduced, others like nickel, chromium and cadmium showed lower removal rates.

Lake Koumoundourou is a shallow meromictic lake located ∼11 km NW of Athens. It is surrounded by various industries and oil refineries, which contaminate the lake by oil spills and leakage. Moreover, the lake receives freshwater from underwater springs, plus drainage from industrialized catchment and Athens landfill. Potential contamination of the lakes' sediments in heavy metals and metalloids was assessed by means of enrichment factors (EFs) estimated against local preindustrial core sediment; elements were normalized to loss on ignition. EFs revealed that surface sediments were enriched in Pb (×10.2), Cu (×6.7), V (×5.1), Ni (×4.1), and other heavy metals. The use of EFs is recommended as a reliable method for heavy metal contamination assessment, provided that (1) element contents are corrected following a careful normalization procedure, (2) local preindustrial sediment is used as reference, and (3) reference sediment should be unaffected by diagenetic alterations.

The Laucala Bay coastal system was investigated from 2003 to 2005 to evaluate the changes in water quality (nutrients) after improvements in sewage effluent quality from Kinoya sewage treatment plant (KSTP), whose output is discharged into the bay. The oxidized nitrogen (NO x -N) values averaged 1.31 µM, but varied from 0.76 to 3.77 µM, and the filterable reactive phosphate or orthophosphate (FRP) averaged 0.77 µM, ranging from 0.24 to 2.37 µM. The mean concentrations of NO x -N and FRP, respectively, were two and ten times higher than concentrations found in unpolluted sites in Fiji. Based on these values and NH₃ concentrations from parallel studies, Redfield ratio estimates suggest that primary productivity of the bay is N limited. No significant decrease in concentration of both NO x -N and FRP was found in Laucala Bay waters during the present investigation compared to concentrations found in two previous studies. This indicates that KSTP effluent may be only a minor source of nutrients into the bay, and to protect the Laucala Bay ecosystem from increasing nutrient pollution, there is a need to control nutrient input from other major point and nonpoint sources.

For upper-division undergraduate or beginning graduate courses in civil and environmental engineering, this text has been revised and modernised to meet the needs of today's environmental engineering students who will be engaged in the design and management of water and wastewater systems.

Naphthenic acids (NAs) are a complex group of naturally occurring oil sands constituents that constitute a significant portion of the dissolved organic carbon (DOC) pool available for microbial degradation in the process-related waste water associated with oil sands mine sites. One approach to understanding the biological fate of oil sands process-derived carbon and nitrogen in aquatic reclamation of the mine sites involves the use of stable isotope analyses. However, for stable isotope analyses to be useful in such field-based assessments, there is a need to determine how microbial degradation of a complex mixture of NAs might change the stable isotope values (δ ¹³C, δ ¹⁵N). In batch cultures and semi-continuous laboratory microcosms, utilization of a commercial mixture of NAs by oil sands-derived microbial cultures resulted in microbial biomass that was similar or slightly ¹³C enriched (1.4[per thousand] to 3.0[per thousand]) relative to the DOC source, depending on the length of incubation. Utilization of a NA-containing extract of oil sands processed water resulted in greater ¹³C enrichment of microbial biomass (8.5[per thousand]) relative to the DOC source. Overall, the δ ¹³C of the DOC comprised of complex mixtures of NAs showed minimal change (-0.5[per thousand] to -0.1[per thousand]) during the incubation period whereas the δ ¹³C of the dissolved inorganic carbon (DIC) was more variable (-5.0[per thousand] to +5.4[per thousand]). In tests where the concentration of available nitrogen was increased, the final biomass values were ¹⁵N enriched (3.8[per thousand] to 8.4[per thousand]) relative to the initial biomass. The isotope trends established in this study should enhance our ability to interpret field-based data from sites with hydrocarbon contamination, particularly in terms of carbon source utilization and ¹⁵N enrichment.

A box-core 3576 (PO287-26-1B) collected from the Tagus Prodelta in 2002 was analysed for organic carbon, ²¹⁰Pb, ²²⁶Ra, major (Al, Fe, Ca, Ti, Mg and Mn) and trace elements (Ba, Hg, Cr, Cu, Li, Ni, Pb, Sb, Sn, Sr, and Zn). Maximum concentrations of contaminants in ²¹⁰Pb-dated samples were reached in the decades between 1960 and 1980, followed by a slightly decrease in up-core metal trends. Trace metal concentrations increased in the bottom of the core (²¹⁰Pb dated as 1925) to maximum values during the 1970s. Factor analysis of geochemical data was used to reduce the 18 variables into four factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Changes in the dominance of these factors through the time indicate not only changes in industrial activity, but also the increase of biological productivity towards the present.

The recurrence of reports citing water quality impairments in watersheds is evidence that tools are needed to identify pollution sources and facilitate restoration efforts such as implementing total maximum daily limits (TMDLs) or best management practices (BMPs). Fecal bacteria in surface waters are one of the most commonly cited impairments to water quality. This study evaluated microbial source tracking (MST), specifically multiple antibiotic resistance (MAR) analysis, as a management tool to differentiate nonpoint source pollution into source groups. A library containing Escherichia coli (E. coli, EC) and fecal streptococci (FS) isolates from poultry (EC n = 282, FS n = 650), human (EC n = 152, FS n = 240), wildlife (EC n = 17, FS n = 43), horse (EC n = 79, FS n = 82), dairy cattle (EC n = 38, FS n = 42), and beef cattle (EC n = 49, FS n = 46) sources was created. The MAR analysis was conducted on the isolates using a profile of seven antibiotics. The antibiotic signatures of unknown source isolates from Elkhorn and Hickman Creek watersheds were evaluated against the library to determine the contributions of potential fecal inputs from the respective sources. Correct classification was >60% when analyzed at the human and non-human-level of classification. On a watershed basis, both watersheds produced similar results; inputs from non-human sources were the greatest contributors to nonpoint source pollution. The results from the multiple antibiotic resistance (MAR) analysis revealed that the information produced, coupled with knowledge of the watershed and its associated land uses, would be helpful in allocating resources to remediate impaired water quality in such watersheds.

The delafossite CuCrO₂ is a promising candidate for the visible light driven catalysis. The NO₂ ⁻ removal by photoelectrochemical process is studied under mild conditions, close to that encountered in the natural environment. CuCrO₂ exhibits a long term chemical stability with a corrosion rate of 0.34 μmol m⁻² year⁻¹ in KCl (0.5 M). A forbidden band of 1.3 eV has been evaluated from the diffuse reflectance spectrum. The flat band potential (-0.07 V SCE) determined from the Mott-Schottky plot is close to the photocurrent onset potential (0 V SCE). Hence, the conduction band is positioned at -1.08 V SCE and thus lies below the NO₂ ⁻ level leading to a feasible reduction upon visible illumination. The conversion occurs in less than ~5 h with a quantum efficiency of ~0.5%. The possibility of identifying the reaction products via the intensity-potential characteristics was explored by using standard solutions. The decrease of the conversion rate over time is attributed to the competitive water reduction. In absence of catalyst, NO₂ ⁻ is oxidized to NO₃ ⁻ in air equilibrated solution and the reaction follows a first order kinetic with a half life of 21 h, NO₃ ⁻ has been identified by iodometry through copper titration.