WWTP Effluent Research Articles

Bioconcentration and toxicity of dodecylbenzene sulfonate (C12LAS) to aquatic organisms exposed in experimental streams.

Fish, mollusks, and crustaceans were caged in the tail pool of streams during a C(12)LAS (dodecyl benzene sulfonate) model ecosystem experimental program. Bioconcentration of total C(12)LAS and individual isomers and acute and chronic toxicity were investigated during this study. Toxicity endpoints were based on water and tissue (i.e., body burden) concentrations at which adverse effects were observed. At 32 days, total C(12)LAS bioconcentration factors (BCFs) for the fathead minnow and three invertebrate species ranged from 9 to 116. In general, bioconcentration was affected by isomer position, exposure concentration, and species. BCF values tended to decrease as isomer position moved from external (e.g., 2-phenyl) to internal (e.g., 5,6-phenyl). BCFs also decreased as exposure concentration increased. Mean acute 4-d LC(50) values ranged from 1.5 to >3.0 mg/L for the six species tested. Lethal body burdens associated with 50% mortality (LBB(50)) varied from 0.21 to 0.60 mmole/kg (wet weight). During the 32-day chronic exposures, the EC(20) values were 0.27 (0.204-0.352), 0.95 (0.597-1.29), and approximately 1.0 mg/L for Corbicula (length), Hyalella (survival), and fathead minnow (survival), respectively. At these EC(20) values, C(12)LAS body burdens were 0.035, 0.23, and 0.19 mmoles/kg wet weight in Corbicula, Hyalella, and fathead minnow, respectively. Fish exposed to wastewater treatment plant effluent had total C(12)LAS tissue concentrations ranging from 0.0005 to 0.0039 mmoles/kg wet weight. These concentrations are approximately 45-360 times below the tissue concentration associated with subtle effects in the model ecosystem stream exposures. Total C(12)LAS body burdens in feral and caged Corbicula exposed to WWTP effluents were approximately 0.0013 mmoles/kg; approximately 25-fold below concentrations associated with effects in stream exposures.

Caffeine, an anthropogenic marker for wastewater comtamination of surface waters.

The suitability of caffeine as a chemical marker for surface water pollution by domestic wastewaters was assessed in this study. Caffeine concentrations in influents and effluents of Swiss wastewater treatment plants (WWTPs, 7-73 and 0.03-9.5 microg/L, respectively) indicated an efficient elimination of 81-99.9%. Corresponding loads in untreated wastewater showed small variations when normalized forthe population discharging to the WWTPs (15.8 +/- 3.8 mg person(-1) d(-1)), reflecting a rather constant consumption. WWTP effluent loads were considerably lower (0.06 +/- 0.03 mg person(-1) d(-1)), apart from installations with low sludge age (< or = 5 d, loads up to 4.4 mg person(-1) d(-1)). Despite the efficient removal in most WWTPs, caffeine was ubiquitously found in Swiss lakes and rivers (6-250 ng/ L), except for remote mountain lakes (<2 ng/L; analytical procedure for wastewater and natural waters: SPE, GC-MS-SIM or GC-MS-MS-MRM, internal standard 13C3-labeled caffeine). Caffeine concentrations in lakes correlated with the anthropogenic burden by domestic wastewaters, demonstrating the suitability of caffeine as a marker. A mass balance for Greifensee revealed that approximately 1-4% of the wastewaters had been discharged without treatment, presumably on rainy days when the capacity of WWTPs had been exceeded. For Zürichsee, it could be shown that the monthly inputs of caffeine correlated with precipitation data. The depth- and seasonal-dependent concentrations in this lake were adequately rationalized by a numerical model considering flushing, biodegradation, and indirect photodegradation via HO. radicals as elimination processes and caffeine inputs as fitting variables.

Pollution based real time control of wastewater systems

Wastewater systems are traditionally built as static systems to handle a design load. The real load varies, though, and hardly ever equals the design load. This implies that wastewater systems hardly ever operate in an optimum way, especially during wet weather. Real time control (RTC) of regulators can improve the operation by better fit of the system to the actual state and load. RTC based on pollutant concentrations together with hydraulic conditions (pollution based real time control, PBRTC) is investigated in this paper to assess the potential pollutant load reduction on receiving waters at wet weather without expansion of transport or storage capacity. Both CSOs and WWTP effluents contribute to the pollutant discharges to receiving waters and both are considered. Three cases are studied to assess the potential benefit of PBRTC. Giving priority to the most polluted wastewater for treatment and storage in branched interceptor systems can reduce CSO discharge loads by more than 20%. Biological WWTPs and especially activated sludge plants are more complex and less stable than chemical precipitation plants during and after high pollutant and hydraulic load. Biological plants can hence profit more from PBRTC than chemical precipitation plants. Receiving waters that are sensitive to acute effects caused by intermittent discharges can benefit more from PBRTC than receiving waters with problems connected to long-term accumulation of pollution.

Innovation of conventional water treatment techniques in effluent reclamation

For reclamation of waste water treatment plant (wwtp) effluent, conventional water treatment techniques used in drinking water supply may be suitable. Earlier studies and experiments showed that the most promising cost-effective conventional techniques to polish wwtp effluent are coagulation and rapid multi-media filtration (direct filtration). In the past 4 years these techniques were tested in long term experiments on pilot scale (5-10 m3/h) at several waste water treatment plants in The Netherlands. For successful application of direct filtration for the removal of suspended solids and colloidal material careful consideration is needed with the coagulation conditions. However additional treatment is required to meet the standards for household and process water with respect to ammonium, colour, pathogens and (biodegradable) organic substances.

Two approaches to indirect potable reuse using membrane technology

A pilot study was conducted at McAllen, Texas to evaluate two microfiltration technologies, Memcor and ZeeWeed, to treat secondary effluent from the city of McAllen south WWTP. The objectives of the study were to compare the ability of Memcor and ZeeWeed to pretreat secondary effluent for subsequent processing by RO and to evaluate the ability of the ZenoGem membrane bioreactor process to directly treat screened, de-gritted wastewater to a quality suitable for direct processing by RO. The results showed both Memcor and ZeeWeed to be competitive in their ability to produce a high quality filtrate from secondary effluent. The results also indicated that the ZenoGem process is capable of producing a filtrate suitable for RO treatment while meeting the City's current wastewater effluent discharge requirements. Additionally, the ZenoGem treated McAllen's raw wastewater to a quality comparable to the city's existing WWTP effluent.

Case Study for: Impact of WWTP effluent on drains water quality in Egypt.

Case Study for: Impact of WWTP effluent on drains water quality in Egypt.

Optimal Combination of Flocculating Filtration and Ultra Filtration for Advanced Effluent Treatment in the Netherlands

With changing policies to solve local environmental and dehydration problems and with increasing interest in differentiation of water qualities by industrial and domestic users, a growing need exists to improve the effluent quality of wastewater treatment plants (wwtp) in the Netherlands. The change of policy to retain water in its original environment as much as possible leads to an increasing interest in discharging wwtp effluent into polders and local water courses instead of large surface waters. Besides, a new element is the interest in the production of household and industry water by the Dutch drinking water companies. At several Dutch wwtp's research on (the combination of) fluocculating filtration and ultra filtration is done to develop the possibilities of (re)using effluent in the Netherlands. The results of the research have shown that flocculating filtration and/or ultra filtration are technically and economically applicable for the production of household and industry water.

Optimal combination of flocculating filtration and ultra filtration for advanced effluent treatment in The Netherlands

With changing policies to solve local environmental and dehydration problems and with increasing interest in differentiation of water qualities by industrial and domestic users, a growing need exists to improve the effluent quality of wastewater treatment plants (wwtp) in the Netherlands. The change of policy to retain water in its original environment as much as possible leads to an increasing interest in discharging wwtp effluent into polders and local water courses instead of large surface waters. Besides, a new element is the interest in the production of household and industry water by the Dutch drinking water companies.At several Dutch wwtp's research on (the combination of) flocculating filtration and ultra filtration is done to develop the possibilities of (re)using effluent in the Netherlands. The results of the research have shown that flocculating filtration and/or ultra filtration are technically and economically applicable for the production of household and industry water.

Modelling the total ammonia impact of CSO and WWTP effluent on the receiving water

For 25 rain events test runs were performed on a catchment of a small town, where 40% of the person equivalents are connected to a separate sewer system and 60% to a combined one. We investigate the effects of rain events with regard to NH4-loads discharged by the wastewater treatment plant and by a combined sewer overflow. NH4-concentrations in the river caused by these loads are also discussed. NH4 is important as (i) it closely interrelates with NH3 – a fish poison – and (ii) it stands for dissolved compounds that mainly origin from the wastewater. The sewer system is simulated with three different options: with a combined water retention tank connected to the CSO structure, with a sewage retention tank at the interface between the separate and the combined system, and without any retention structure. While the sewage retention tank performs better concerning the integrated load discharged into the river, the combined sewer retention tank is more efficient in decreasing peak values and duration of high concentrations in the river. We also show that NH4 peak concentrations in the river are largely due to a wash-out effect in the main sewer at the beginning of a rain event.

Modelling the total ammonia impact of CSO and WWTP effluent on the receiving water

Modelling the total ammonia impact of CSO and WWTP effluent on the receiving water

Creep-fatigue interaction for 2.25 Cr1Mo steel under combined loadings: Kubo, K., Yagi, K., Kaneko, T. and Umezawa, O. J. Soc. Mater. Sci., Jpn. Dec. 1988 37, (423), 1429–1435 (in Japanese)

The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing.