Adsorption behavior of diclofenac-containing wastewater on three kinds of sewage sludge

Microbial diversity and metabolic inference of diclofenac removal in optimised batch heterotrophic-denitrifying conditions by means of factorial design

Using the Response Surface Methodology (RSM) and Rotational Central Composite Design (RCCD), this study evaluated the removal of DCF under denitrifying conditions, with ethanol as cosubstrate, in batch reactors, being 1 L Erlenmeyer flasks (330 mL of reactional volume) containing Dofing medium and kept under agitation at 130 rpm and incubated at mesophilic temperature (30 °C). It considered the individual and multiple effects of the variables: nitrate (130 - 230 mg NO3- L-1), DCF (60-100 µg DCF L-1) and ethanol (130 - 230 mg EtOH L-1). The highest drug removal efficiency (17.5%) and total nitrate removal were obtained at 176.6 ± 4.3 mg NO3 -L-1, 76.8 ± 3.7 µg DCF L-1, and 180.0 ± 2.5 mg EtOH L-1. Under such conditions, the addition of ethanol and nitrate was significant for the additional removal of diclofenac (p > 0.05). The prevalence of Rhodanobacter, Haliangium and Terrimonas in the inoculum biomass (activated sludge systems) was identified through the 16S rRNA gene sequencing. The potential of these genera to remove nitrate and degrade diclofenac was inferred, and the main enzymes potentially involved in this process were α-methylacyl-CoA racemase, long-chain fatty acid-CoA ligase, catalases and pseudoperoxidases.

Efficiency of Diclofenac Removal Using Activated Sludge in a Dynamic System (SBR Reactor) with Variable Parameters of pH, Concentration, and Sludge Oxygenation

Recently, traditional wastewater treatment systems have not been adapted to remove micropollutants, including pharmaceutical substances, which, even at low concentrations, cause adverse changes in aquatic and terrestrial living organisms. The problem of drug residues in the environment has been noticed; however, no universal legal regulations have been established for concentrations of these compounds in treated wastewater. Hence, the aim of the article was to determine the possibility of increasing the efficiency of diclofenac removal from activated sludge using the designed SBR reactor. This study included six cycles, working continuously, where each of them was characterized by changing conditions of pH, oxygenation, and composition of the synthetic medium. In each cycle, three concentrations of diclofenac were analyzed: 1 mg/L, 5 mg/L, 10 mg/L for the hydraulic retention time (HRT) of 4 d and the sludge retention time (SRT) of 12 d. The highest removal efficiency was achieved in the first test cycle for pH of natural sediment at the level of 6.7-7.0 (>97%), and in the third test cycle at pH stabilized at 6.5 (>87%). The reduced content of easily assimilable carbon from synthetic medium indicated a removal of >50%, which suggests that carbon in the structure of diclofenac restrained microorganisms to the rapid assimilation of this element. Under half-aerobic conditions, the drug removal effect for a concentration of 10 mg/L was slightly above 60%.

Cosmetic wastewater treatment technologies: a review

Over the past three decades, environmental concerns about the water pollution have been raised on societal and industrial levels. The presence of pollutants stemming from cosmetic products has been documented in wastewater streams outflowing from industrial as well as wastewater treatment plants. To this end, a series of consistent measures should be taken to prevent emerging contaminants of water resources. This need has driven the development of technologies, in an attempt to mitigate their impact on the environment. This work offers a thorough review of existing knowledge on cosmetic wastewater treatment approaches, including, coagulation, dissolved air flotation, adsorption, activated sludge, biodegradation, constructed wetlands, and advanced oxidation processes. Various studies have already documented the appearance of cosmetics in samples retrieved from wastewater treatment plants (WWTPs), which have definitely promoted our comprehension of the path of cosmetics within the treatment cycle; however, there are still multiple blanks to our knowledge. All treatments have, without exception, their own limitations, not only cost-wise, but also in terms of being feasible, effective, practical, reliable, and environmentally friendly.

The influence of aeration rate on the sorption of emerging pharmaceuticals in activated sludge

The sorption of pharmaceuticals on activated sludge during the wastewater treatment process has been widely studied and considered one of the main mechanisms for the removal of these micropollutants from domestic sewage. Understanding the removal mechanism is important to reduce the environmental risk associated with these compounds. To the best of our knowledge, no data are reporting the influence of the aeration rate and, consequently, of the physicochemical properties of the sludge flocs, on the sorption of pharmaceutical compounds. In this context, the influence of the aeration rate (2, 5, and 8 L min^-1) on the physical properties of the sludge and the sorption of two emerging pharmaceuticals, 17-alpha-ethynylestradiol (EE2) and diclofenac (DCF), was evaluated. The pharmaceuticals were analyzed by Solid Phase Extraction and Liquid Chromatography, and the sludge by Laser Particle Size Analyzer and Settling Curves. As a result, higher sorption for 17-alpha-ethinylestradiol (78-96%) in comparison to diclofenac (23-43%) was observed, corroborating the greater hydrophobicity of EE2. Higher pharmaceuticals removal rates were observed for the highest aeration (10.02 µgEE2 gSST^-1 and 3.99 µgDCF gSST^-1) in comparison to the lowest one (7.81 µgEE2 gSST^-1 and 2.58 µgDCF gSST^-1), what can be attributed to structural and surface changes in flocs. Smaller and more dispersed flocs were observed when aeration was increased (104.4 µm for 8 L min^-1 and 63.8 µm for 2 L min^-1). The results suggest that the increase in aeration seems to be promising for the removal of pharmaceuticals by sorption in sewage sludge, especially for the hydrophobic ones.

Kinetic and isotherm insights of Diclofenac removal by sludge derived hydrochar

Recently, hydrothermal carbonization emerges as the most viable option for the management of solid waste with high moisture content. Sludge derived hydrochar is used as an adsorbent for emerging contaminants or micro-pollutants in the domain of sustainability. Current study demonstrates the KOH activation of hydrochar produced from paper board mill sludge and evaluates its removal potential of a Non-steroidal anti-inflammatory drug, Diclofenac from aqueous solution. The activated hydrochars exhibited porous, spherical micro-structures with higher fraction of oxygenated functional groups paving way for the efficient adsorption of Diclofenac. The effect of initial Diclofenac concentration and contact time was ascertained using adsorption kinetics and isotherms. The adsorption kinetics exhibited second-order reaction for all adsorbents indicating higher coefficient of determination (R² > 0.9). The Diclofenac adsorption on hydrochars followed Langmuir isotherm model with the post-activated hydrochar recording a highest adsorption capacity of 37.23 mg g⁻¹ in 40 mg L⁻¹ initial Diclofenac concentration at 15 h equilibrium time.

Sewage sludge in agriculture - the effects of selected chemical pollutants and emerging genetic resistance determinants on the quality of soil and crops - a review

In line with sustainable development principles and in order to combat climate change, which contributes to progressive soil depletion, various solutions are being sought to use treated sewage sludge as a soil amendment to improve soil quality and enrich arable soils with adequate amounts of biogenic compounds. This review article focuses on the effects of the agricultural use of biosolids on the environment. The article reviews the existing knowledge on selected emerging contaminants in treated sewage sludge and describes the impact of these pollutants on the environment and living organisms based on 183 publications selected from over 16,000 papers on related topics published over the last ten years. This study deals not only with chemical contaminants but also genetic determinants of resistance to these compounds. Current research has questioned the agricultural use of biosolids due to the presence of mutual interactions between antibiotics, heavy metals, the genetic determinants of resistance (antibiotic resistance genes - ARGs and heavy metal resistance genes - HMRGs) and non-steroidal anti-inflammatory drugs as well as the risks associated with their transfer to the environment. This study emphasizes the need for more extensive legal regulations that account for other pollutants of environmental concern (PEC), particularly in countries where sewage sludge is applied in agriculture most extensively. Future research should focus on more effective methods of eliminating PEC from sewage sludge, especially from the sludge that is used to fertilize agricultural land, because even small amounts of these micropollutants can have serious implications for the health and life of humans and animals.

Occurrence of the main metabolites of pharmaceuticals and personal care products in sludge stabilization treatments

In Europe, approximately 40% of sludge yearly produced in wastewater treatment plants (WWTPs) is applied in agricultural lands as organic amendment, especially in arid regions. Sludge tends to concentrate wastewater pollutants. Many of them are not removed by sludge stabilization treatments and, as a result, they could originate adverse effects on soils, vegetation, animals, and humans. Although sludge stabilization treatments play an important role in removal contaminants from sludge and, therefore, in preventing contaminant discharges onto soils, there is scarce information about the occurrence of these compounds in these treatments. This fact is especially acute for emerging pollutants and, particularly, their metabolites. In this work, seven pharmaceuticals and personal care products, and their main metabolites, have been monitored in five different stabilization treatments: anaerobic and aerobic digestion, dehydration, composting, and lagooning. Sixteen compounds were measured in the analysed samples. Their distribution was similar in primary sludge, in spite of the different geographic locations of the WWTPs, The distribution was in accordance with the metabolic ratios of most of the studied compounds. Different behaviour was observed depending on the compound, for example, CBZ, 3-OH-CBZ, DIC, and 4-OH-DIC were highly persistent in all studied stabilization technologies whereas CAF, PX showed high degradability. Most of the studied compounds were measured in the final product of the sludge stabilization processes evaluated. This fact shows the necessity to improve the knowledge about the presence of these compounds in sludge intended to be applied onto soil and about the potential ecotoxicological risks of these compounds.