Elevated radium (Ra) concentrations have been observed in aquifers with high naturally occurring salinity. The flux of radon (Rn) gas from the decay of Ra out of saline aquifers can be enhanced owing to salting-out effects. This raises the issue as to whether increased salinization of groundwater from road deicing practices can enhance Ra and Rn mobility to the extent that they become a human health concern. Continued use of salt (NaCl) as a road deicing agent has resulted in a gradual salinization of groundwater systems in snow-affected regions. This study presents groundwater data from a monitoring well field installed around a permeable pavement parking lot at the University of Connecticut, Storrs campus. The data suggest a connection between road salting and (a) the mobilization of dissolved Ra as well as (b) enhanced Rn gas flux from the water table. A positive correlation (R ² = 0.92) was identified between dissolved Na⁺ and isotopes of Ra; a negative relationship was observed between specific conductance and dissolved Rn. In two monitoring locations, concentrations of Ra were detected that exceeded the EPA MCL of 5 pCi/L. Concentrations of Rn in the groundwater were found to be at a level that theoretically could generate gas concentrations in the vadose zone that exceed the indoor Rn standard by orders of magnitude. Given these findings, it appears that salt contamination of groundwater could increase the potential for human exposure to these radioactive and carcinogenic elements. Graphical Abstract Photo of the study area taken 1/14/16

In this study, cassava starch wastewater was subjected to coagulation/flocculation (C/F) combined with microfiltration (MF) to improve the final quality of treated water. In the C/F tests of the effluent, the best concentration of the natural coagulant (Tanfloc POP) was determined from a statistical analysis of color removal and turbidity data. The supernatant produced in the C/F step was subjected to MF while varying the transmembrane pressure to evaluate the permeate fluxes, fouling mechanism, and permeate quality. The mathematical model that best represented the filtration process was the fouling mechanism of partial membrane pore blockage. The best experimental conditions for coagulant dosage, settling time, and MF pressure in the combined C/F-MF process were 320 mg L⁻¹, 15 min, and 1.4 bar, respectively. The highest overall removal efficiency rates achieved were 99% color, 91% cyanide, 75% total organic carbon, and 100% turbidity, demonstrating the promising potential of the combined C/F-MF process in the treatment of cassava starch wastewater.

Research was conducted on the most polluted river system in Poland, impacted by active and historical mining. Bottom sediment, suspended particulate matter and river water were collected in 2014 from Przemsza river and its tributaries. Sampling points remained the same as those chosen in a 1995 study. This allowed the comparison of heavy metal accumulation in bottom sediment over a span of almost two decades. It was concluded that Przemsza river water and its tributaries are heavily contaminated with the following (in μg/dm³): Pb (0.99–145.7), Zn (48–5020), and Cd 0.12–12.72). Concentrations of metals in bottom sediment exceeded the background values by a factor of several hundred (100 times for Zn, 150 times for Pb, and 240 times for Cd). The arithmetic mean for metal concentration in fractions <63 μm sampled in 2014 has remained comparable to the level found in 1995 (in mg/kg): Zn 16,918 and 13,505, Pb 4177 and 4758, and Cd 92 and 134. It was determined that 20–50% more metals have accumulated in suspended matter, rather than in bottom sediment (in mg/kg): 20,498 Zn, Pb 5170, and 164 Cd. This exceeds the limits of the most polluted LAWA Class IV classification. Since the concentrations of Zn, Pb, and Cd increase drastically after the outlet of the Przemsza into the Vistula, it was concluded that river Przemsza is the cause of significant degradation of Vistula’s bottom sediment and suspended matter. A two-decade legacy of extremely high contamination of the Przemsza river sediments has persisted despite decreasing mining and smelting activity in the vicinity.

The current study aims to tackle one of the main obstacles in the application of anaerobic ammonium oxidation (Anammox) technology, i.e., the extreme slow growth of the Anammox bacteria. Three conventional sludge has been tested in sequencing batch reactor for Anammox enrichment, including conventional aerobic sludge, denitrification sludge, and anaerobic sludge. With a high selection stress and insufficient oxygen control, the reactor seeded with aerobic sludge reached 50–60% total nitrogen removal after 240 days whereas that seeded with anaerobic sludge failed to establish Anammox activity. Anammox process was successfully established in the reactor seeded with denitrification sludge with a total nitrogen removal of approximately 80% after 150 days under strict oxygen control (DO <0.2 mg/L) and low selection stress. Under the same operational condition, the reactor seeded with anaerobic sludge reached only 20–30% total nitrogen removal. All the reactors experienced fluctuating performances during the enrichment process, which was believed to be the consequence of inhibitory factors such as dissolved oxygen, nitrite and free ammonia as well as undesirable coexisting bacteria which compete for the same substrate. The denaturing gradient gel electrophoresis (DGGE) band from the amplified DNA samples extracted from different enrichment stage showed a clear evolution of the microbial composition as reflected by the change in the band locations and their intensity.

Organic matter and nutrient in pig manure were treated using an integrated filter system. The influent flowed into an anaerobic filter (AF), and the AF effluent was polished in a biological aerated filter (BAF). The filter system was operated with recirculation ratios of 1–3. The filter system was operated with two recirculation methods. When a filter system was operated under bottom recirculation conditions, the nitrated effluent from the BAF was mingled with the influent in the AF. For upper recirculation conditions, the nitrated effluent from the BAF was injected into a height of 36% from the bottom in the AF. Removal of organic matter and nitrogen under upper recirculation conditions was greater than those under bottom recirculation conditions. The average chemical oxygen demand and solids removals were over 99 and over 97% under upper recirculation conditions. Total nitrogen and total phosphorus removals were over 77 and over 69% at recirculation 3 under upper recirculation conditions.

The selection of emergent plants is of primary importance during the construction of floating treatment wetlands (FTWs). Focusing on the comparison of the nitrogen removal, pot-culture experiments were carried out in floating treatment wetlands constructed with Phragmites australis and Acorus calamus in northeast China, a cold temperate zone. Nitrogen removal and transformation processes were investigated to explore the pathways and factors that influence the nitrogen removal. FTWs showed a high capacity for nitrogen removal. In water with TN concentrations of 9.63 and 4.58 mg L⁻¹, the average TN removal efficiencies of the FTWs constructed with P. australis were 91.5 and 84.2%, respectively, and those of FTWs constructed with A. calamus were 84.2 and 82.8%, respectively. Plant uptake accounted for 36.4 to 77.1% of total N removal. The average TN removal rates of P. australis systems in the first 2 days were 4.20 and 1.77 mg L⁻¹ day⁻¹ for treatments with TN concentrations of 9.36 and 4.58 mg L⁻¹, respectively, significantly higher than those of the A. calamus system, which were 1.75 and 1.04 mg L⁻¹ day⁻¹, respectively. Our results suggested that plant uptake was the main pathway for nitrogen removal in FTWs, and P. australis was a suitable emergent plant species for use in FTW construction in a cold temperate zone.

Hexavalent chromium (Cr(VI)) in wastewater is a great risk to the quality of water sources and to human health. Meanwhile, Chinese herb-extraction residues (CHER) are the by-products from the extraction process of Chinese medicine. This study investigated the use of CHER to adsorb Cr(VI) from aqueous solution. Results indicated that adsorption was maximum at solution pH of 2.0 while the Cr(VI) removal efficiencies for chuanxiong rhizome residue (CRR) and Chinese wolfberry residue (CWR) were 86.56 and 99.93%, respectively. Isotherm data were modeled by using Freundlich, Langmuir, and Temkin isotherms. The maximum monolayer adsorption capacities for CWR and CRR were 79.60 and 36.21 mg g⁻¹, while their corresponding adsorption capacities obtained from experimental data were 37.30 and 32.42 mg g⁻¹, respectively. However, Freundlich isotherm fitted the data well. Both adsorption and reduction of Cr(VI) to Cr (III) forms followed by complexation onto the adsorbent surfaces favored removing Cr(VI). The results also suggested that the abundant and cheaply available CRR and CWR can be used as efficient adsorbent materials for Cr(VI) removal from wastewater.

According to our previous results on the magnesium-based exhaust gas cleaning system (Mg-EGCS), certain parameters of the desulphurization wastewater (such as chemical oxygen demand (COD), suspended solids (SS), total oil content and turbidity) were above the washwater discharge criteria set by the International Maritime Organization (IMO). In this work, a novel combined process of aeration-centrifugation and filter pressing was proposed, and a pilot-scale experiment was carried out to treat the desulphurization wastewater. The results demonstrated that the quality of wastewater treated by the combined process could meet the IMO’s washwater discharge standard, with COD of 115 mg/L, SS of <5 mg/L, polycyclic aromatic hydrocarbons (PAHs) of <1 μg/L, and total oil content of 5.1 mg/L, when the washwater flow rate was 0.45 m³/h.

Aeration of the biological reactor in wastewater treatment plants (WWTPs) represents one of the major cost items, which may account for more than 50% of the total energy consumption. Therefore, airflow rate must be supplied based on the real needs of the biological reactions and the goals to be achieved in terms of removal efficiency and effluent quality. Among the different strategies available to optimize energy consumption of air supply, the Oxy Fuzzy logic and oxidation reduction potential (ORP)-based control systems have proven to be efficient and reliable. The present study compares the effects of these two control systems in terms of energy consumption and efficiency of COD and ammonia oxidation in the activated sludge reactors of two WWTPs for domestic sewage. Both systems allowed to largely comply with the limits set on the effluent for COD and ammonia in spite of the dynamic pattern of the influent load. The Oxy Fuzzy system led to reducing energy consumption by 13% while the ORP control system only by 2%, as average per year. The Oxy Fuzzy system showed higher flexibility, being more capable of adapting the set-points in relation to the influent load. The ORP system seemed to be more suitable for plants where the influent load does not change significantly: the set-points are fixed and the input load can be properly managed only for limited variations.

This study analysed the effectiveness of innovative (basalt meal, brown algae extract) and conventional (barley straw) substances which hypothetically alleviate the inhibiting effect of Cd²⁺ on biochemical properties of soil, with particular regard to the activity of arylsulfatase. An analysis of their potential was carried out based on the activity of arylsulfatase and the number of Pseudomonas sp. determined on the 25th and 50th days of the study. Cd²⁺ was applied in the following doses: 0, 4, 40, 80, 120, 160, 200 mg Cd²⁺ kg⁻¹ of DM soil, in the form of CdCl₂·2.5H₂O. A complex formulation of the issue was obtained from the presentation of biochemical properties using the RS (resistance of soil) index. Cadmium caused permanent adverse effects in the soil environment, inhibiting the activity of arylsulfatase and the yield of spring barley. The consequences of stress connected with increasing Cd²⁺ pollution were intensified by an elongation of the accumulation time of the tested metal in the soil. Chances for regeneration of the soil may be sought, most of all, with the application of straw and, to a lesser degree, with basalt meal. Brown algae did not meet the expectations for its potential. An increase in the studied parameters also resulted from sowing the soil with spring barley.