Water pollution through natural and anthropogenic activities has become a global problem causing short-and long-term impact on human and ecosystems. Substantial quantity of individual or mixtures of organic pollutants enter the surface water via point and nonpoint sources and thus affect the quality of freshwater. These pollutants are known to be toxic and difficult to remove by mere biological treatment. To date, most researches on the removal of organic pollutants from wastewater were based on the exploitation of individual treatment process. This single-treatment technology has inherent challenges and shortcomings with respect to efficiency and economics. Thus, application of two advanced treatment technologies characterized with high efficiency with respect to removal of primary and disinfection by-products in wastewater is desirable. This review article focuses on the application of integrated technologies such as electrohydraulic discharge with heterogeneous photocatalysts or sonophotocatalysis to remove target pollutants. The information gathered from more than 100 published articles, mostly laboratories studies, shows that process integration effectively remove and degrade recalcitrant toxic contaminants in wastewater better than single-technology processing. This review recommends an improvement on this technology (integrated electrohydraulic discharge with heterogeneous photocatalysts) viz-a-vis cost reduction in order to make it accessible and available in the rural and semi-urban settlement. Further recommendation includes development of an economic model to establish the cost implications of the combined technology. Proper monitoring, enforcement of the existing environmental regulations, and upgrading of current wastewater treatment plants with additional treatment steps such as photocatalysis and ozonation will greatly assist in the removal of environmental toxicants.

Ion exchange processes are effective for the removal of arsenic (As) from drinking water. However, the As uptake capacity of ion exchange resins is affected by the presence of other anions such as sulphates and nitrates. As these ions are typically found in groundwater, the design of ion exchange process aimed at removing As from groundwater may be affected by their presence. Therefore, to properly design an ion exchange process for As removal, it is important to characterise the ion exchange equilibria of As in solution in the presence of competing anions. This paper was aimed at obtaining a deeper understanding of the binary equilibria of As(V)Cl⁻ and SO₄ ²⁻/Cl⁻ and of the ternary equilibria of As(V)/SO₄ ²⁻/Cl⁻. To this purpose, a series of batch tests were carried out at different values of the total solution normality. These data were combined with those obtained through continuous flow column tests performed to collect equilibrium data over the entire ionic fraction domain. The equilibrium data were then described using two different models based on the assumption of ideal behaviour of both the liquid and the adsorbed phases: in the first model the resin was considered to have only one type of binding-sites, where two types of binding sites were assumed by the second model, named double-selectivity model. Among these two models, the latter provided the best fitting of binary equilibrium data for both As chlorides and sulphate chlorides systems. However, the same model was unable to fit the experimental data of As in the ternary system As(V)/SO₄ ²⁻/Cl⁻ with a satisfactory agreement probably due to the presence of non-ideality which the model did not account for.

Soils that are exposed to floodwaters because of shallow groundwater and periodical wetlands are, to a large extent, exposed to contamination by organic and inorganic compounds. These are mainly compounds that have drifted along with the inflow of heavily laden floodwater and are produced within the soil profile by the anaerobic transformation of organic matter. Heavy metals and polycyclic aromatic hydrocarbon (PAH) compounds are absorbed by the soil of the floodwaters, and moving in the soil profile, they pose a threat to groundwater. What is more, after a flood, they may be absorbed by the crops. This paper focuses on the effects of Odra River (Poland) floods, heavy metals, and PAHs on soil and the possibilities of the migration of these pollutants into the soil profile. In the tested sludge samples of floodwater and soil, there were no abnormal concentrations of heavy metals, but the flooding time positively affected the amount listed in the test samples. Concentrations of PAHs increased, but they also exceeded the standards for arable soils in the case of single compounds.

Normal seed germination of native herbaceous species can be reduced by high concentrations of deicer products and their constituent salts. Chloride salts are commonly used during the winter months in temperate climates to remove ice and snow. Although these products greatly improve driving conditions, they can have detrimental effects on the vegetation growing along highways. The purpose of this laboratory study was to determine the impact of a magnesium-based deicer product and a sodium-based deicer product and the major salts they contain on the germination and viability of several species of grasses and forbs native to Colorado and planted in revegetation seedings there. Seeds were placed on blotter paper saturated with either a water control, one of three concentrations of each of the deicing solutions, or one of three concentrations of a pure NaCl or MgCl₂ solution. Increasing concentrations of salt ions generally resulted in delayed and reduced normal seed germination, especially the sodium- and magnesium-based deicer solutions. Germination for most species was lower when seeds were grown in deicer solution compared with germination percent of seeds grown in the pure salt solutions. Some species were more tolerant of one of the salts and deicers. Species with C4 photosynthetic pathway were more tolerant than C3 species of high concentrations of both deicer products. Those species which attained the highest germination percent under moderate or high solution concentrations included blue grama, buffalograss, little bluestem, mountain brome, and slender wheatgrass.

Parts of the Czech Republic received extreme loading of acid deposition from coal combustion in the second half of the twentieth century. Although associated Hg deposition was not directly measured, Hg deposition rates calculated from peat cores approach 100 μg m⁻² year⁻¹. We quantified the soil concentrations and pools of Hg with carbon (C), sulfur (S), and nitrogen (N)—elements closely associated with soil organic matter at five sites across the Czech Republic—four sites known for extreme deposition levels of S and N compounds in the twentieth century, and one site relatively less impacted. The site-specific means of O-horizon Hg concentrations ranged from 277 to 393 μg kg⁻¹, while means of Hg concentrations in mineral soil ranged from 22 to 95 μg kg⁻¹. The mean Hg/C ratio across sites increased from ∼0.5 μg Hg g⁻¹C in the Oi-horizon to ∼5 μg Hg g⁻¹C in the C-horizon due to the progressive mineralization of soil organic matter. The soil Hg/C increase was accompanied by a soil C/N decrease, another indicator of soil organic matter mineralization. Soil Hg/C also increased as soil C/S decreased, suggesting that Hg was stabilized by S functional groups within the soil organic matter. Mineral soil Hg pools (8.9–130.0 mg m⁻²) dominated over organic soil Hg pools (5.3–10.1 mg m⁻²) at all sites. Mineral soil Hg pools correlated more strongly with total soil S and oxalate-extractable Fe than with total soil C. Total soil Hg pools could be accounted for by a time period of atmospheric inputs that was short relative to the age of the soils. The cross site variability of Hg soil pools was not sensitive to the local Hg deposition history but rather related to the capacity of soil to store and stabilize organic matter.

Microcystis aeruginosa, the most common toxic cyanobacterial bloom, could cause severe environmental problem by producing and releasing lethal cyanobacterial toxins to water body. This study investigated the electron beam irradiation for the inactivation of M. aeruginosa. The treatment process was monitored via the measurement of chlorophyll a concentration, optical density, photosynthesis, and antioxidant enzymes. At low electron beam irradiation dose (1.0 kGy), its performance is not desirable. High dosage of electron beam irradiation (2.0–5.0 kGy) can dramatically decrease chlorophyll a concentration, optical density, and photosynthesis rate and affect activities of antioxidant enzymes. The transmission electron microscopy measurement indicates that electron beam irradiation treatment cause significant damages on integrity and morphology. Our results demonstrate that electron beam irradiation is a promising technique for quick and efficient inactivation of M. aeruginosa in aqueous solution.

The effect of anaerobic digestion (AD), coarse solids removal, and a manure additive More Than Manureᵀᴹ (MTMᵀᴹ) on ammonia (NH₃) emission from raw (Non AD) dairy manure and AD manure was studied during 110 days of storage. The study consisted of eight treatments in duplicate: AD manure and non AD manure, with and without coarse solids, and with and without MTMᵀᴹ additive. These studies were conducted in a naturally ventilated barn. The nitrogen content of manure, especially the ammoniacal nitrogen, played an important role in NH₃ emission. During the first 11 weeks of the storage, AD manure had significantly greater peak (33 to 38 ppm) concentrations of NH₃, and NH₃ fluxes (94 to 130 μg min⁻¹ m⁻²) compared to raw manure (14 to 25 ppm and 55 to 81 μg min⁻¹ m⁻², respectively). From the 11th week until the end of storage, there was no significant difference in NH₃ emissions across the manure treatments. The presence of course solids resulted in significanlty less peak NH₃ for non AD manure when data were evaluated for the whole storage period. The manure additive MTMᵀᴹ did not have a significant effect on NH₃ emissions during storage, however, temperature was positively related to NH₃ emissions. Total ammoniacal nitrogen and solids concentration in manure was the most important factors affecting NH₃ emissions during storage.

Many of municipal wastewater treatment plants (WWTPs) are operated by biological process with their excellent performances. However, the early warning system in the influent line is required to avoid the process malfunction because the biological wastewater treatment system has serious drawback to toxic chemicals in the influent. In order to develop a new type of biosensor using anaerobic granules in an online device for rapid detection of toxic inhibitory to the biological process, a porous pot reactor and an anaerobic granule biosensor (AGB) were demonstrated as an upset early warning device (UEWD) in this study. In the first group of toxic loading tests, the prepared cupric chloride solutions were separately injected into both the porous pot and AGB systems at six different concentrations, and phenol solutions were used at three different concentrations in the second group of tests. The results showed the chemical oxygen demand (COD) and ammonia nitrogen (ammonia-N) removal efficiency from porous pot reactor decreased dramatically in response to the addition of Cu²⁺and phenol with the variation of the oxidation-reduction potential (ORP) in AGB. The response of AGB system was 6 to 20 h in advance of porous pot reactor performance response, which suggests that the AGB could potentially be used as an online UEWD.

Wastewater treatment works can receive toxic substances that can kill microorganisms responsible for waste degradation. Implementation of toxicity monitors in-sewer, as part of an early warning system to help prevent toxic substances entering treatment works, is, however, very rare. This work presents results from a pilot-scale study using an in-sewer early warning system based on detection of nitrous oxide (N₂O) gas emitted by nitrifying bacteria naturally present in sewer biofilm. Nitrous oxide has potential to be an indicator of nitrification inhibition as it is typically emitted when nitrifiers are under stress. The biofilm was allowed to develop over 14 days under fixed wastewater flow and level. Presence of nitrifying bacteria was verified on day 13 followed by a 90 min toxic shock on day 14 by four different known nitrification inhibitors. Pre-shock nitrification rates averaged 0.78 mg-NH₄⁺-N mg-VS⁻¹ d⁻¹and were significantly reduced post shock to <0.2 mg-NH₄⁺-N mg-VS⁻¹ d⁻¹. Nitrous oxide emissions were found to vary with influent wastewater quality, suggesting a more complex data processing algorithm is needed instead of a simple threshold emission value. The extent of nitrification inhibition differed from the recorded response for suspended growth biomass with allylthiourea resulting in a 77 and 81 % nitrification inhibition for literature suspended growth EC₅₀and EC₇₅concentrations, respectively. Results from this study suggest nitrifying biofilms in closed pipes can be used as part of an early warning system but will likely require amplification of the response to be of practical use. Further research is required to better understand the biofilm response and calibrate the early warning system for differentiating its unique baseline from true toxicity events.

This paper presents a comprehensive analysis of the pollutant emissions and intensity from Canada’s power stations. An analysis of National Pollutant Release Inventory (NPRI) and site generation data shows significant variability with the dominant emissions pathway being point-source air emissions. In general, power stations are a very small fraction of Canada’s direct facility and estimated diffuse emissions, as well as showing significant variability of pollutant intensities per megawatt or megawatt hour of capacity or generation. The evidence also suggests that increased scale does not lead to a lower pollutant intensity, and that transfers and disposal pollutant loads are substantial, often representing most of the total reported pollutants. Overall, this study provides a valuable insight into the current status of pollutant intensities from Canada’s power stations, possible improvements to the NPRI and a valuable benchmark for future studies and international comparisons.