Secondary Effluent Of Wastewater Treatment Plant Research Articles

Experimental verification of tertiary treatment process in achieving effluent quality required by wastewater reuse standards

Modern technologies in wastewater treatment can produce high quality effluents, therefore wastewater is now considered a valuable product suitable for reuse. However, water reuse needs to be regulated based on applicable and legally binding guidelines, therefore the lack of a regulatory framework hampers this practice and its benefits. The Czech Republic, as many other countries, has an absent water reuse legislation. In this study, a pilot-scale tertiary treatment was installed at Milevsko Waste Water Treatment Plant (WWTP) in South Bohemia (20,000 P.E.) to demonstrate the effluent quality that can be achieved and evaluate the reuse potential, especially on non-potable applications, such as industry and irrigation. WWTP secondary effluent was treated by three separated technologies: Dissolved Air Flotation (DAF), sand filter and Filtra-lite® filter; followed by ultraviolet (UV) disinfection. Results on water quality were compared to Czech standards for drinking and non-drinking water, and to some international benchmark regulations for water reuse. Our results have led us to initiate the introduction of legislation regulating wastewater reuse in the Czech water management framework.

Study on operating flux of plate ceramic membrane treating municipal secondary effluent of WWTP

In recent years, plate ceramic membrane has been applied in the field of water and wastewater treatment successfully, because of its unique advantages. As an important parameter which can characterize properties of membrane, the water flux and critical flux of plate ceramic membrane treating municipal secondary effluent of Wastewater Treatment Plant(WWTP) were studied in this paper. And the flux change characteristics under different membrane pressure were obtained. The experimental results laid foundation for further exploring of mechanism of membrane fouling and related control techniques, and provided references for expanded application of plate ceramic membrane in wastewater reuse.

Transformation of erythromycin during secondary effluent soil aquifer recharging: Removal contribution and degradation path

Erythromycin (ERY), a widely used antibiotic, has recently been detected in municipal secondary effluents and poses serious threats to human health during wastewater reusing. In this study, the removal, fate, and degradation pathway of ERY in secondary effluent during soil aquifer treatment was evaluated via laboratory-scale SAT tests. Up to a 92.9% reduction of ERY in synthetic secondary effluent was observed in 1.0m depth column system, which decreased to 64.7% when recharged with wastewater treatment plant secondary effluent. XRD-fractionation results demonstrated that the transphilic acid and hydrophobic acid fractions in secondary effluent compete for the adsorption sites of the packed soil and lead to a declined ERY removal. Moreover, aerobic biodegradation was the predominant role for ERY removal, contributing more than 60% reduction of ERY when recharged with synthetic secondary effluent. Destruction of 14-member macrocyclic lactone ring and breakdown of two cyclic sugars (l-cladinose and d-desosamine) were main removal pathways for ERY degradation, and produced six new intermediates.

Identifying the major fluorescent components responsible for ultrafiltration membrane fouling in different water sources

Three-dimensional fluorescence excitation–emission matrix (EEM) coupled with parallel factor analysis (PARAFAC) was performed for a total of 18 water samples taken from three water sources (two lakes and one wastewater treatment plant (WWTP) secondary effluent), with the purpose of identifying the major ultrafiltration (UF) membrane foulants in different water sources. Three fluorescent components (C1, C2 and C3) were identified, which represented terrestrially derived humic-like substances (C1), microbially derived humic-like substances (C2), and protein-like substances (C3). The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components (C1, C2 and C3) made a considerable contribution to the irreversible and total fouling of the UF membrane. However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.

Degradation of N,N-diethyl-m-toluamid (DEET) on lead dioxide electrodes in different environmental aqueous matrixes

This study investigates the electrochemical degradation of N,N-diethyl-m-toluamide (DEET) on PbO2 and Bi-PbO2 anodes. The difference in electrode crystalline structure was responsible for the better DEET degradation and TOC removal on PbO2 than on Bi-PbO2. In 1 M Na2SO4, the degradation efficiency and apparent rate constant (kapp) of DEET oxidation on PbO2 increased with the increase in current density or temperature (activation energy = 24.4 kJ mol−1). The kapp values in DEET-spiked environmental matrixes (municipal wastewater treatment plant secondary effluent (MWTPSE), groundwater (GW), and river water (RW)) were the same (6.05 × 10−4 s−1), but significantly smaller than that in 1 M Na2SO4 (2.23 × 10−3 s−1). The TOC removal efficiency was better in MWTPSE than in RW and GW; however, the mineralization current efficiencies in MWTPSE and RW were similar but higher than that in GW. During electrolysis, the aromaticity was lower in GW than in RW.

Electrospun nanofibre membranes functionalised with TiO2 nanoparticles: Evaluation of humic acid and bacterial removal from polluted water

This study presents contact experiments and filtration tests with nanofibre membranes containing TiO2 nanoparticles in view of effluent treatment. The first part of this study focuses on the removal of dissolved organic matter, more specifically humic acids. Removal of humic acids from secondary wastewater treatment plant effluent as well as from synthetic water solutions was tested. Also the bactericidal effect of the TiO2 functionalised nanofibre membranes was examined. Contact experiments with TiO2 functionalised membranes showed removal of humic acids (83% degradation after 2h) and Staphylococcus aureus (4.5log10/100ml after 6h). Also the possibility of using (TiO2 functionalised) nanofibre membranes for effluent filtration in view of water reuse, was examined. Such secondary effluent filtration tests improved water quality as a reduction in turbidity (69%), humic acids (37%) and bacterial activity (76%) was observed. It can be concluded that nanofibre membranes could be used as a high-flux filtration technique for effluent recuperation.

Microcontaminant degradation in municipal wastewater treatment plant secondary effluent by EDDS assisted photo-Fenton at near-neutral pH: An experimental design approach

This work aims to evaluate the applicability of EDDS (ethylenediamine-N,N′-disuccinic acid) as an iron chelating agent for photo-Fenton treatment of municipal wastewater spiked with organic contaminants at near-neutral pH. A series of laboratory scale experiments are conducted under simulated sunlight in accordance with a central composite experimental design in order to define the most favorable conditions in terms of initial iron concentration (maintaining a molar ratio 1:2 of Fe:EDDS), H2O2 and pH. The system is evaluated in terms of degradation efficiency, H2O2 consumption and iron availability. The simulated system has been compared in terms of degradation efficiency with a 60L compound parabolic collector (CPC), and significant correlation has been observed. An approach for estimating near-optimal regions of operability is also demonstrated.

Electrochemical degradation of N,N-diethyl-m-toluamide on a boron-doped diamond electrode

This study investigates the electrochemical oxidation of N,N-diethyl-m-toluamide (DEET) on a boron-doped diamond (BDD) anode under different temperatures, current densities, and sample matrixes. For comparison, a commercial Pt electrode and a lab-prepared PbO2 anode were also tested. The oxidation of DEET on BDD was found to be electrochemically irreversible. The degradation of DEET increased with the increase of current density, but was slightly influenced by temperature (25–75°C). Furthermore, the BDD anode was superior to the Pt and PbO2 electrodes with regard to DEET abatement and total organic carbon (TOC) removal. At 0.75A/cm2 and 50°C, the pseudo-first-order rate constants of DEET oxidation were 5.00×10−3–8.98×10−3s−1 in DEET-spiked 1M Na2SO4 solution, municipal wastewater treatment plant secondary effluent (MWTPSE), groundwater (GW), and river water (RW), significantly greater than that (4.73×10−4s−1) in DEET-spiked industrial wastewater (IW). The TOC removal in the real environmental matrixes followed the order MWTPSE>GW≈RW≫IW. Through electrochemical oxidation, DEET was completely mineralized in the DEET-spiked MWTPSE.

Removal of pharmaceuticals from a WWTP secondary effluent by ultrafiltration/reverse osmosis followed by electrochemical oxidation of the RO concentrate

This study aims to assess the removal of emerging contaminants from municipal wastewaters using a pilot system that integrated ultrafiltration (UF), reverse osmosis (RO), and electrooxidation, which mineralized the RO concentrate. Initially, the study monitored 77 emerging contaminants in the influent and effluent of a wastewater treatment plant (WWTP). Most of the compounds were detected in significant amounts in the WWTP effluent.A group of 12 compounds that represent the most prevalent therapeutic pharmaceutical categories was selected to monitor their removal by UF/RO. For the majority of the micropollutants, the UF removal efficiency was less than 20%. Excellent removal efficiencies were achieved with the RO treatment. As a result, the concentrations of the emerging contaminants in the RO permeate varied between 44ng/L for naproxen and 4ng/L for ofloxacin, and furosemide, bezafibrate and fenofibric acid were not detected. After the RO treatment, electrooxidation of the RO concentrate with boron-doped diamond electrodes reduced the total micropollutant content in the RO concentrate from 149μg/L to less than 10μg/L. Increasing the intensity of the electrooxidation treatment is expected to further reduce the micropollutant concentrations.

Post-treatment of secondary wastewater treatment plant effluent using a two-stage fluidized bed bioreactor system

The aim of this study was to investigate the performance of a two-stage fluidized bed reactor (FBR) system for the post-treatment of secondary wastewater treatment plant effluents (Shahrak Gharb, Tehran, Iran). The proposed treatment scheme was evaluated using pilot-scale reactors (106-L of capacity) filled with PVC as the fluidized bed (first stage) and gravel for the filtration purpose (second stage). Aluminum sulfate (30 mg/L) and chlorine (1 mg/L) were used for the coagulation and disinfection of the effluent, respectively. To monitor the performance of the FBR system, variation of several parameters (biochemical oxygen demand (BOD5), chemical oxygen demand (COD), turbidity, total phosphorous, total coliform and fecal coliform) were monitored in the effluent wastewater samples. The results showed that the proposed system could effectively reduce BOD5 and COD below 1.95 and 4.06 mg/L, respectively. Turbidity of the effluent could be achieved below 0.75 NTU, which was lower than those reported for the disinfection purpose. The total phosphorus was reduced to 0.52 mg/L, which was near the present phosphorous standard for the prevention of eutrophication process. Depending on both microorganism concentration and applied surface loading rates (5–10 m/h), about 35 to 75% and 67 to 97% of coliform were removed without and with the chlorine addition, respectively. Findings of this study clearly confirmed the efficiency of the FBR system for the post-treatment of the secondary wastewater treatment plant effluents without any solid problem during the chlorination.

Correlations of relevant membrane foulants with UF membrane fouling in different waters

Correlations between potential fouling-relevant substances and membrane fouling during ultrafiltration (UF) of different waters were investigated, including water samples from Lake Tegel, from a Berlin canal (Landwehrkanal) and from a wastewater treatment plant (WWTP) secondary effluent. The biopolymers quantified with liquid chromatography-organic carbon detection (LC-OCD) showed a remarkable correlation with UF membrane fouling for all the three water sources at different seasons. This finding suggests that the biopolymer content in water can be employed as a universal indicator for predicting membrane fouling potential in UF processes. The particulate matter in the two surface waters Lake Tegel and Berlin canal, as characterized by suspended solids and turbidity, also exhibited a distinct correlation with UF membrane fouling, although its correlation was slightly weaker than that of biopolymers. However, the humic substances, which are generally believed to be major membrane foulants, did not show any reliable correlation with the UF membrane fouling of the different waters. This work may provide useful information for the development of optimized fouling control strategies for sustainable UF operation.

Ozonation performance of WWTP secondary effluent of antibiotic manufacturing wastewater

The ozonation performance of wastewater treatment plant secondary effluent of oxytetracycline (OTC) manufacturing wastewater was investigated in terms of ozone dosage and initial pH levels when OTC contributed to a negligible fraction in the chemical oxygen demand (COD) ingredients of the medium-organic-strength wastewater with low biodegradability. A particular emphasis was placed on ammonia, OTC, and residual antibacterial activity (RAA) (evaluated using the objective pathogenic bacterium Staphylococcus aureus). It appears that an ozone dosage of 657 mg L −1 (120 min of reaction) was enough to achieve an OTC abatement of 96%, and COD and biochemical oxygen demand removals of 29% and 33%, respectively, at initial levels of 10.4, 1360, and 300 mg L −1, respectively. There is a clear correlation between complete OTC depletion and complete RAA disappearance with an increase of ozone dosage. The presence of plentiful non-antibiotic refractory substances influenced the determination of the optimum ozone dosage for biodegradability enhancement and OTC/RAA reduction as well as the ozonation transformation of NH 3. The initial pH adjustment from the original level (pH 9) to pH 11 significantly reduced COD removal while RAA and NH 3 levels were not significantly influenced.

Application of the new solution ACTIDisc® on secondary effluent reclamation in Castellón de la Plana

During the month of May 2005, the performances of ACTIDisc® process were tested in Castellón de la Plana WWTP (waste water treatment plant), in collaboration with FACSA and Entitat de Sanejament d’Aigües Residuals de la Generalitat Valenciana. The purpose of the analysis was to prove the suitability of ACTIDisc® process in wastewater reclamation of the WWTP secondary effluent. The process aimed, mainly, to achieve a low level of suspended solids and turbidity in compliance with the regulations proposal for direct reuse of treated effluents, suggested in 2005 as AEAS guidelines.

Understanding natural organic matter fouling in low-pressure membrane filtration

Natural organic matter (NOM) in natural water is responsible for significant organic fouling of low pressure membranes. Membrane fouling can be affected by the characteristics of the NOM and its interaction with the membranes and their associated properties. Three different water sources were tested for this study; river water, wastewater treatment plant secondary effluent and water with high content of DOC and humic substances. Three different types of low pressure flat sheet membranes (MF and UF) were selected which are equivalent simulation of commercial hollow fiber membranes, and dead-end, stirred cell filtrations were performed. From the water source characterization, Scottsdale WWTP secondary effluent has high content of high molecular weight compounds corresponding to colloids and/or macromolecules by SEC-DOC/UV and showed significant flux decline in all of membrane filtration. Tampa water contain relatively less high molecular weight compounds and showed significant flux decline comparing to White River water. This may be due to over three time higher DOC content than other water sources. Thus, the water containing high colloids and macromolecules as well as high DOC content is very problematical in low-pressure membrane fouling. SEC-DOC/UV spectrum of backwashed stream proved that hydraulically reversible foulants are high molecular weight compounds and those molecules are likely to cause significant flux decline by cake layer formation on membrane surface.

A comparative ecological and toxicological investigation of a secondary wastewater treatment plant effluent and its receiving stream

AbstractA comparative ecological and toxicological investigation was conducted on a secondary wastewater treatment plant point—source discharge and the receiving system, a fourth—order freshwater stream in the Kentucky River basin. Biological, chemical, hydrological and on—site toxicological studies were performed at 10 monitoring stations, including reference sites. The principal objectives were to assess downstream persistence of aquatic contaminants, to quantify their effects on structure and function of aquatic communities and to evaluate the 8—d fathead minnow embryo—larval test for measuring instream toxicity and estimating chronic effects on aquatic biota. The principal ecological endpoints included species richness, diversity (H'), density and dominance (D) of macroinvertebrates and diversity of fish species. Macroinvertebrates were further analyzed by trophic groups. Marked downstream gradients existed for effluent dilution, decreasing concentration of selected chemicals, improvement in ecological conditions and decreasing toxicity, as measured in on—site static—renewal tests. A good predictive correlation was found between embryo—larval survival and independent ecological parameters, especially species richness of macroinvertebrates. In addition, static—renewal and flow—through toxicity tests were performed with effluent dilutions to determine LC50 and toxicity threshold values (LC1), expressed as percent effluent by volume. The estimated toxicity thresholds correlated closely with the actual percent instream effluent dilution observed at the first downstream station at which no ecological impact was discernible.

QUALITY OF STORMWATER DRAINAGE FROM URBAN LAND1

ABSTRACT Urban storm water from a 1,067‐acre drainage basin in Durham, N.C. was characterized to determine yield of pollutants. Population density averaged 9 persons per acre (ranging from <3 to 16). Annual BOD contribution attributable to surface wash during storms was determined to be approximately equal to contribution by its secondary wastewater treatment plant effluent. Total organic matter (COD) was estimated to exceed the amount in raw sanitary sewage from a residentially developed area of the same size. Mean basin yields (Ib/acre/day) were: BOD‐0.23, COD‐2.85, Total Solids‐43.6, Volatile Total Solids‐4.8, Total Phosphate‐0.01 and Chloride‐0.20 (as NaQ). The yield of lead presumed to originate from internal combustion engines operating on and near the basin was determined to be 0.006 Ib/acre/day. The concentration of total pesticides (Dieldrin; p,p'DDE; p,p‐DDT; p,p'DDD and p,p'DDT) weighted for flow significance was estimated to be 1.2 parts per billion. The major long‐term pollutional impact on a projected downstream reservoir was considered to be the fixed solids residue and long‐term oxygen demand (COD). Intermittent release of other pollutants in slugs during runoff periods may be a significant factor in causing undesirable effects in streams draining urban areas.