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The growth status, root exudates, radial oxygen loss, and sewage purification effect of plants acclimated with sewage and cultured with a nutrient solution were studied by selecting Acorus gramineus Aiton, Pistia stratiotes L., and Eichhornia crassipes (Mart.) Solms with the same individual size. The results showed that the root oxygen secretion rate of the Acorus gramineus Aiton was higher in light and dark conditions. For a single plant species, the oxygen secretion rate under light conditions was much higher than that under dark conditions. The root oxygen secretion rate of Acorus gramineus Aiton was the highest (2.03 µmol O2/h/plant), followed by Pistia stratiotes L. (1.68 µmol O2/h/plant), and the root oxygen secretion rate of Eichhornia crassipes (Mart.) Solms was the lowest (1.15 µmol O2/h/plant). After a period of adaptation, plants showed strong removal effects on COD, NH3-N, TN, and TP. The removal intensity was in the order of Acorus gramineus Aiton > Pistia stratiotes L. > Eichhornia crassipes (Mart.) Solms; the higher the temperature, the bigger the removal rate. These results were consistent with Acorus gramineus Aiton's organic matter secretion and radial oxygen loss, which were better than those of Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms. Three kinds of plants had better COD removal effects in an acidic environment and better TP removal effects in an alkaline environment. The results show that using the Acorus gramineus Aiton can achieve better remediation of polluted water bodies. [ABSTRACT FROM AUTHOR]

In this study, a modified horizontal settling tank with rotating biological discs was developed to treat slightly polluted surface water, and its performance on the simultaneous removal of turbidity, organics, and NH 4 + -N was investigated on a lab scale. Results show that the effluent quality of the modified settling tank is stable in more than two months of continuous operation. At a hydraulic retention time (HRT) of 2.0 h, 73.65 ± 5.15% turbidity, 53.98 ± 5.17% TOC, and 77.01 ± 10.02%, NH 4 + -N could be removed by the modified settling tank with an average of 1.96 NTU turbidity, 1.98 mg/L TOC, and 0.46 mg/L NH 4 + -N residue in the effluent. Due to the improvement in DO supply, higher removal efficiencies of both organics and NH 4 + -N were achieved with increased disc rotating speed (r < 4 r/min). Further study showed that the genus Hyphomicrobium dominant on the posterior discs and the genus Nitrospira dominant on the anterior discs mainly contributed to the enhanced bio-oxidation of organics and NH 4 + -N, respectively. [ABSTRACT FROM AUTHOR]

Large-scale fumaric acid chemical brownfield sites have posed a significant obstacle to environmental safety, public safety, and the redevelopment of brownfield sites. A comprehensive study was conducted to determine the main pollution indicators, soil pollution characteristics, and the multiple potential risks to the environment and the ecosystem of a fumaric acid brownfield site in northwestern China. The results showed that 1,2,3-trichloropropane(1,2,3-TCP) was the primary pollutant at the fumaric acid brownfield site. The atmospheric volatile organic compounds (VOCs) in this brownfield site did not exceed the Chinese standard limits. The soil contamination was more severe within the site, with a total of about 30 VOCs detected, including the uncommon brominated pollutants. The level of longitudinal soil contamination decreased with increasing soil depth. The distillation area was more contaminated with a maximum exceedance multiple of 11,291.8. The longitudinal contamination depths in the distillation and reactor zones were 10.0 m and 4.0 m, respectively. Soil texture and production processes are considered to be one of the influencing factors for the depth of vertical soil contamination. Our findings heighten the awareness of brownfield site soil contamination and provide a reference for contamination controls and the comprehensive management of fumaric acid brownfield sites. [ABSTRACT FROM AUTHOR]

More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions. [ABSTRACT FROM AUTHOR]