Tag Archives: wastewater treatment

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A Model for Developing Water and Sanitation Capacity

Occurrence and Removal of Phthalates from Wastewater

Gani KM, Tyagi VK, Kazmi AA. Occurrence of phthalates in aquatic environment and their removal during wastewater treatment processes: a review. Environ Sci Pollut Res Int. 2017 May 31. doi: 10.1007/s11356-017-9182-3.

Phthalates are plasticizers and are concerned environmental endocrine-disrupting compounds. Due to their extensive usage in plastic manufacturing and personal care products as well as the potential to leach out from these products, phthalates have been detected in various aquatic environments including drinking water, groundwater, surface water, and wastewater. The primary source of their environmental occurrence is the discharge of phthalate-laden wastewater and sludge. This review focuses on recent knowledge on the occurrence of phthalate in different aquatic environments and their fate in conventional and advanced wastewater treatment processes. This review also summarizes recent advances in biological removal and degradation mechanisms of phthalates, identifies knowledge gaps, and suggests future research directions.

Can Wastewater Microbes Metabolize Pharmaceuticals?

Balcom IN, Driscoll H, Vincent J, Leduc M. Metagenomic analysis of an ecological wastewater treatment plant’s microbial communities and their potential to metabolize pharmaceuticals. F1000Res. 2016 Jul 28;5:1881. doi: 10.12688/f1000research.9157.1. eCollection 2016.

Pharmaceuticals and other micropollutants have been detected in drinking water, groundwater, surface water, and soil around the world. Even in locations where wastewater treatment is required, they can be found in drinking water wells, municipal water supplies, and agricultural soils. It is clear conventional wastewater treatment technologies are not meeting the challenge of the mounting pressures on global freshwater supplies. Cost-effective ecological wastewater treatment technologies have been developed in response. To determine whether the removal of micropollutants in ecological wastewater treatment plants (WWTPs) is promoted by the plant-microbe interactions, as has been reported for other recalcitrant xenobiotics, biofilm microbial communities growing on the surfaces of plant roots were profiled by whole metagenome sequencing and compared to the microbial communities residing in the wastewater. In this study, the concentrations of pharmaceuticals and personal care products (PPCPs) were quantified in each treatment tank of the ecological WWTP treating human wastewater at a highway rest stop and visitor center in Vermont. The concentrations of detected PPCPs were substantially greater than values reported for conventional WWTPs likely due to onsite recirculation of wastewater. The greatest reductions in PPCPs concentrations were observed in the anoxic treatment tank where Bacilli dominated the biofilm community. Benzoate degradation was the most abundant xenobiotic metabolic category identified throughout the system. Collectively, the microbial communities residing in the wastewater were taxonomically and metabolically more diverse than the immersed plant root biofilm. However, greater heterogeneity and higher relative abundances of xenobiotic metabolism genes was observed for the root biofilm.

Phosphate Adsorption Using a Novel Filter Substrate

Wang W, Ma C, Zhang Y, Yang S, Shao Y, Wang X. Phosphate adsorption performance of a novel filter substrate made from drinking water treatment residuals. Journal of Environmental Sciences (China). 2016 Jul;45:191-9. doi: 10.1016/j.jes.2016.01.010. Epub 2016 Feb 26.

Phosphate is one of the most predominant pollutants in natural waters. Laboratory experiments were conducted to investigate the phosphate adsorption performance of a (NFS) made from drinking water treatment residuals. The adsorption of phosphate on the NFS fitted well with the Freundlich isotherm and pseudo second-order kinetic models. At pH 7.0, the maximum adsorption capacity of 1.03mg/g was achieved at 15°C corresponding to the wastewater temperature in cold months, and increased notably to 1.31mg/g at 35°C. Under both acidic conditions (part of the adsorption sites was consumed) and basic conditions (negative charges formed on the surface of NFS, which led to a static repulsion of PO4(3-) and HPO4(2-)), the adsorption of phosphate was slightly inhibited. Further study showed that part of the adsorption sites could be recovered by 0.25mol/L NaOH. The activation energy was calculated to be above 8.0kJ/mol, indicating that the adsorption of phosphate on NFS was probably a chemical process. Considering the strong phosphate adsorption capacity and recoverability, NFS showed great promise on enhancing phosphate removal from the secondary treated wastewater in the filtration process.

Microfiltration of Oil Sands Process-Affected Water

Shimiao Dong, Eun-Sik Kim, Alla Alpatova, Hiroshi Noguchi, Yang Liu, Mohamed Gamal El-Din. Treatment of oil sands process-affected water by submerged ceramic membrane microfiltration system. Separation and Purification Technology Volume 138, 10 December 2014, Pages 198–209

With the rapid expansion of the oil sands in Northern Alberta over past decade, oil sands process-affected water (OSPW) management has become a significant issue. Currently, there is an urgent need for the OSPW reuse and/or safe discharge. In this study, coagulation followed by submerged microfiltration (MF) with a range of ceramic membranes was investigated as a potential process for pretreating OSPW. The ceramic MF membranes with the average pore size of 100 nm were made of Al2O3 and their selective layer was further modified with SiO2 or TiO2 nanoparticles. Our results showed that membrane surface charge played an important role in controlling membrane fouling. The maximum fouling reduction was achieved when OSPW was treated by SiO2-modified membrane. Surface roughness studies also demonstrated its significant effect on membranes’ filtration performance and fouling. More foulants were deposited on the surface of rough TiO2-modified membrane as compared to smoother SiO2-modified membrane. It was found that removal of organic and inorganic fractions in OSPW was not affected neither by the type/concentration of coagulant nor by membrane’s surface modification. Thus, more than 93% removal of the total suspended solids and less than 17% and 10% removals of the total organic carbon (TOC) and chemical oxygen demand (COD), respectively, were achieved regardless of the membrane type and applied treatment. When MF permeate was used as an influent to the reverse osmosis (RO), this resulted in 98% and 100% reductions in TOC and COD concentrations, respectively. Moreover, RO filtration achieved more than 95% removal of magnesium, calcium, iron, fluoride, chloride, sulfate, nitrate, sodium and potassium and silica. The results of this study showed that combination of RO and MF could be considered as an effective and feasible option for OSPW treatment.

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Lagoon Performance Assessed Using Fluoride as a Tracer

Ruffino B. Fluoride tracer test for the performance analysis of a basin used as a lagooning pre-treatment facility in a WTP. Environmental Science and Pollution Research International. 2015 Feb 1.

The water treatment plant (WTP) of the city of Torino (NW Italy), which treats about 40 · 106 m3/year of raw water from Po river, has a 15-ha basin used as a lagooning pre-treatment facility. Since the efficiency of the lagooning process in the removal of pollutants from raw water depends on the internal hydrodynamics of the basin, the hydraulic performance of the basin was studied by combining the results of a stimulus-response tracer test with the monitoring of the tracer (fluoride) concentration throughout the basin at different times. The outcomes of the test demonstrated that the system was efficiently mixed and could be assimilated to a continuous stirred reactor presenting no flow anomalies, with an actual mean residence time (RT) of 12.7 days, compared with a nominal RT of 18 days. This assured that dissolved contaminants (such as fluoride) coming from the river were efficiently diluted before entering the WTP. The axial dispersion coefficient calculated from the RT distribution was approximately 47,300 m2/day. Three of the most popular formulae developed for the calculation of the axial dispersion coefficient provided results spreading over three orders of magnitude, thus showing their limitations. Finally, because of the width extent of the basin and the characteristics of its inflow, the 1-D advection-dispersion model failed in predicting the tracer concentration values in time at the outlet channel. On the contrary, the analytical solution of the 2-D advection-dispersion model proved to be suitable to fit the tracer concentration data over time at the outlet channel but it failed in describing the tracer distribution throughout the basin on the monitoring dates.

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Dynamic Model of a Submerged Membrane Bioreactor

Guilherme A. Pimentel, Alain Vande Wouwer, Jerome Harmand , Alain Rapaport. Design, analysis and validation of a simple dynamic model of a submerged membrane bioreactor Water Research 70 (2015) 97 e108

In this study, a simple dynamic model of a submerged membrane bioreactor (sMBR) is proposed, which would be suitable for process control. In order to validate the proposed model structure, informative data sets are generated using a detailed simulator built in a well-established environment, namely GPS-X. The model properties are studied, including equilibrium points, stability, and slow/fast dynamics (three different time scales). The existence of slow-fast dynamics is central to the development of a dedicated parameter estimation procedure. Finally, a nonlinear model predictive control is designed to illustrate
the potential of the developed model within a model-based control structure. The problem of water treatment in a recirculating aquaculture system is considered as an application example.

The article is here (fee).