Synthetic Wastewater Effluent Research Articles

Simultaneous Oxidation of Trace Organics and Sorption of Trace Metals by Ferrate (Fe(VI))-Coated Sand in Synthetic Wastewater Effluent.

The increased presence of toxic chemicals in aquatic matrices and their associated health effects raise the need for more effective treatment technologies. The application of Fe(VI), an advanced oxidation treatment agent with disinfecting and coagulating capabilities, is limited by Fe(VI) aqueous instability. Our previous study proposed an Fe(VI)-coated sand media to overcome this constraint and demonstrated that Fe(VI)-coated sand was an effective medium for the treatment of phenolic compounds. In this study, we assessed the potential of the media for treatment of acetaminophen (ACM), benzotriazole (BZT), sulfamethoxazole (SMX), copper (Cu), lead (Pb), and zinc (Zn)-common contaminants found in wastewater effluents-in ultrapure and synthetic wastewater effluent. Fe(VI)-coated sand reactivity was influenced by the solution pH and aqueous chemistry. For example, the removal of Pb improved by 39% in the presence of trace organics, indicating that trace metal removal was enhanced by Fe(III) phases formed during Fe(VI) reactions with trace organics. While oxidation of trace organic compounds increased as pH decreased, trace metal sorption was more favorable at higher pH (i.e., pH 8 and 9). The oxidation efficiency of trace organics by the media was the highest for ACM and SMX while BZT degradation was limited due to formation of Cu-BZT complexes. Batch tests in synthetic wastewater effluent revealed that the presence of divalent cations (i.e., Ca2+ and Mg2+) can catalyze Fe(VI) self-decay and promote Fe(III) production and subsequent trace metal removal; however, oxidation of trace organics was hindered in this matrix. This study highlights the potential for Fe(VI)-coated sand application for the treatment of complex matrices more representative of natural and engineered aquatic systems.

Efficient peroxymonosulfate activation by nanoscale zerovalent iron for removal of sulfadiazine and sulfadiazine resistance bacteria: Sulfidated modification or not

Whether it’s necessary to extra chemical synthesis steps to modify nZVI in peroxymonosulfate (PMS) activation process are worth to further investigation. The 56 mg/L nZVI/153.65 mg/L PMS and 56 mg/L sulfidated nZVI (S-nZVI) (S/Fe molar ratio = 1:5)/153.65 mg/L PMS) processes could effectively attain 97.7% (with kobs of 3.7817 min−1) and 97.0% (with kobs of 3.4966 min−1) of the degradation of 20 mg/L sulfadiazine (SDZ) in 1 min, respectively. The nZVI/PMS system could quickly achieve 85.5% degradation of 20 mg/L SDZ in 1 min and effectively inactivate 99.99% of coexisting Pseudomonas. HLS-6 (5.81-log) in 30 min. Electron paramagnetic resonance tests and radical quenching experiments determined SO4•−, HO•, 1O2 and O2•− were responsible for SDZ degradation. The nZVI/PMS system could still achieve the satisfactory degradation efficiency of SDZ under the influence of humic acid (exceeded 96.1%), common anions (exceeded 67.3%), synthetic wastewater effluent (exceeded 90.7%) and real wastewater effluent (exceeded 78.7%). The high degradation efficiency of tetracycline (exceeded 98.9%) and five common disinfectants (exceeded 96.3%) confirmed the applicability of the two systems for pollutants removal. It’s no necessary to extra chemical synthesis steps to modify nZVI for PMS activation to remove both chemical and biological pollutants.

Treatment of a Biological Effluent Containing Metronidazole

Emerging pollutants like metronidazole (MNZ) affect the removal efficiency of conventional activated sludge (CAS) based wastewater treatment plants and can escape traditional treatment facilities. Advanced oxidation processes (AOPs) and membrane filtration could complement the existing processes to completely eliminate pollutants of emerging concern in wastewaters. This work investigated the application of photochemical processes for treating a synthetic wastewater effluent from CAS treatment and membrane filtration of the biological effluents after CAS experiments with MNZ, caffeine (CAF) and ibuprofen (IBU). Photochemical experiments were conducted in a batch photochemical reactor. The influence of different chemical species such as H2O2, Fe(II), K2S2O8 and TiO2 and of pH value in the system were studied in terms of TOC removal and MNZ degradation. The application of UV/K2S2O8/Fe(II) resulted in 78 % TOC removal in the effluent. Complete degradation of MNZ was observed after 30 min of treatment in the following experiments: UV/H2O2/Fe(II) at pH 3 and UV/K2S2O8. Moreover, the effluents were treated by means of a membrane bioreactor (MBR). Polycarbonate track-etch membranes of 50 and 100 nm pore size were used. The results obtained showed that the carbon removal by the MBR was comparable with the conventional biological treatment. Rejection of MNZ depends on the presence/absence of other emerging contaminants in the wastewater effluents.

Adsorption behavior of perfluorooctanesulfonate (PFOS) onto activated spent coffee grounds biochar in synthetic wastewater effluent

Improved understanding of human health risks, environmental persistence, and widespread dispersion of per- and polyfluoroalkyl substances (PFAS) has driven ongoing development of stringent regulations for these compounds in water. Char materials produced from agricultural food waste have recently been explored as alternatives to granular activated carbon for PFAS removal in water. Herein, spent coffee grounds (SCG) were pyrolyzed, activated with alkaline hydroxide, and evaluated for perfluorooctanesulfonate (PFOS) adsorption. At environmentally-relevant PFOS concentrations, pyrolyzed SCG showed minimal PFOS removal while activated SCG removed 9.9%–99.6% of PFOS depending on activation conditions. SCGKOH (produced from a 1:1 mass ratio of pyrolyzed SCG and potassium hydroxide) had a maximum adsorption capacity of 43.4 mg/g compared to Filtrasorb® F300 activated carbon (55.7 mg/g) and a wood-based fly ash char (79.5 mg/g). All adsorbents display non-linear pseudo first-order adsorption behavior with rate constants of 0.414 h−1, 0.062 h−1, 0.090 h−1 for fly-ash biochar, SCGKOH and F300, respectively. Additionally, PFOS removal by all adsorbents decreased in the presence of simulated effluent organic matter. SCGKOH presents an exciting alternative to existing commercial char adsorbents. The widely available feedstock and low-input production process could make this material a viable water treatment option for resource-constrained communities.

Evaluating the effect of hydraulic retention time on fouling development and biomass characteristics in an algal membrane photobioreactor treating a secondary wastewater effluent

Coupling algal biomass growth to wastewater treatment is a promising alternative for the simultaneous removal and recovery of nutrients. This study aims to evaluate the effects of the Hydraulic Retention Time (HRT) on the fouling behavior and biomass characteristics of C. Vulgaris in a Membrane Photobioreactor (MPBR), fed with a secondary synthetic wastewater effluent. The changes in the algal cell characteristics and in their metabolic products were assessed at three different HRTs (12 h, 24 h and 36 h). Experimental results showed that higher loading rates led to a broader Particle Size Distribution (PSD) resulting from looser and less stable algal flocs. In contrast, bigger and homogeneously distributed particles observed at lower loading rates, led to a porous layer with lower fouling rates and organic removal. The presence of smaller particles and dissolved organics resulted in a more compact and less porous layer that increased the removal of small-MW organics.

Biotransformation of estrone, 17β-estradiol and 17α-ethynylestradiol by four species of microalgae

Natural and synthetic estrogens have been widely detected in wastewater treatment plant (WWTP) influent and effluent as well as in the corresponding receiving aqueous environment and other ecosystems. Microalgae can be used to remove nitrogen and phosphorus in wastewater, but the species-dependent removal of estrogens needs further investigation. In this study we investigated estrone, 17β-estradiol and 17α-ethynylestradiol removals and transformation products by four common microalgae Haematococcus pluvialis, Selenastrum capricornutum, Scenedesmus quadricauda, and Chlorella vulgaris. It was found that H. pluvialis, S. capricornutum and S. quadricauda could more effectively remove all three estrogens in synthetic wastewater effluent. The estrogenic activities i.e. 17β-estradiol equivalency determined by yeast estrogenic screening assay showed substantial estrogenic activity reductions after biotransformation by H. pluvialis, S. capricornutum, and S. quadricauda. Quadrupole Time-of-flight Mass Spectrometry results identified several possible ring-cleavage metabolites as well as their metabolic pathways, which had not been reported yet, confirming the estrogen degradation rather than mere absorption or uptake by microalgae. The findings demonstrate that not only can some specific bacteria degrade estrogens, but also the widely living microalgae are able to degrade these emerging pollutants, suggesting that microalgae could be an advanced treatment of WWTPs to remove nutrients and estrogens.

Fouling control in a forward osmosis process integrating seawater desalination and wastewater reclamation

A hybrid system that combines forward osmosis with a reverse osmosis seawater desalination process could reduce both energy requirements and environmental impacts by osmotic dilution of the seawater and concentrated brine with an impaired low salinity stream, such as treated wastewater effluent. In this study, we investigate the membrane fouling behavior in forward osmosis under conditions simulating the osmotic dilution process and the use of hydrodynamic methods without the use of cleaning chemicals, to control membrane fouling. Fouling runs with seawater or SWRO brine draw solution and deionized (DI) water feed solution showed insignificant water flux decline, which implies negligible effect of particulate and organic matter in the seawater/brine on fouling of the FO membrane support layer. Fouling of the membrane active layer was evaluated by using an enriched synthetic wastewater effluent containing a mixture of inorganic and organic foulants, focusing on the impact of permeate drag force on fouling layer formation. Our results demonstrate that higher permeate water flux causes an increase in concentration build-up of foulants at the membrane surface, thereby forming a dense inorganic/organic combined fouling layer during FO fouling runs. We also examined three hydrodynamic methods for minimizing FO membrane fouling in the osmotic dilution process: (1) applying shear force on the membrane surface by increasing the cross-flow velocity, (2) using a feed-channel spacer to induce turbulence, and (3) employing pulsed flow to remove foulants from the membrane surface. Our results show that these hydrodynamic methods substantially reduce fouling and flux decline rate.

Characterization of intermediate products of solar photocatalytic degradation of ranitidine at pilot-scale

In the present study the mechanisms of solar photodegradation of H 2-receptor antagonist ranitidine (RNTD) were studied in a well-defined system of a pilot plant scale Compound Parabolic Collector (CPC) reactor. Two types of heterogeneous photocatalytic experiments were performed: catalysed by titanium-dioxide (TiO 2) semiconductor and by Fenton reagent (Fe 2+/H 2O 2), each one with distilled water and synthetic wastewater effluent matrix. Complete disappearance of the parent compounds and discreet mineralization were attained in all experiments. Furthermore, kinetic parameters, main intermediate products, release of heteroatoms and formation of carboxylic acids are discussed. The main intermediate products of photocatalytic degradation of RNTD have been structurally elucidated by tandem mass spectrometry (MS 2) experiments performed at quadrupole-time of flight (QqToF) mass analyzer coupled to ultra-performance liquid chromatograph (UPLC). RNTD displayed high reactivity towards OH radicals, although a product of conduction band electrons reduction was also present in the experiment with TiO 2. In the absence of standards, quantification of intermediates was not possible and only qualitative profiles of their evolution could be determined. The proposed TiO 2 and photo-Fenton degradation routes of RNTD are reported for the first time.

Influence of biofouling on boron removal by nanofiltration and reverse osmosis membranes

Excess of boron in water poses a problem due to adverse effects on crop production as well as human health and aquatic life. This study examined the influence of biofouling of NF and RO membrane on the performance of the membranes in removing boron from a synthetic wastewater effluent. Accelerated laboratory-scale biofouling experiments were carried out with commercial thin film composite NF and RO membranes under controlled conditions. Permeate flux decline, down to less than 25% of its initial value, and substantial decrease in boron rejection were attributed to extensive biofilm growth on the membranes. For the RO membrane, boron rejections declined by 45 and 34% of the initial values for influent boron concentrations of 5.5 and 1.1 mg B/L, respectively, whereas the corresponding declines in boron rejection for the NF membrane were 44 and 13% of the initial values. These adverse effects of biofilm growth on permeate water flux and boron rejection are attributed to both an increase in hydraulic resistance to permeate flow due to bacterial extracellular polymeric substances (EPS) and a biofilm-enhanced concentration polarization near the membrane surface.

Development of a lamellar flow biofilm reactor for waste water treatment

A lamellar flow multiplate biofilm reactor has been developed in this work and tested with a synthetic waste water effluent. A mixed culture biofilm readily develops within a few days and attaches itself to the synthetic textile used as a support medium. Conversion levels are promising. The bioreaction has been modelled with first order kinetics for COD levels < 125 mg/L and with zero order kinetics for higher COD values. The aerobic conversion predominates at lower COD levels while at higher COD levels, the aerobic conversion is confined solely to the external surface of the biofilm and the remainder of the digestion is done anaerobicly.