Journal of Environmental Engineering

This study demonstrates that aerobic granules can be developed to achieve high phenol loading rates in a sequencing batch reactor. The reactor was started at a loading rate of 1.5 $\mathrm{kg}\mathrm{phenol}{m}^{-3}{d}^{-1}$ with phenol-enriched activated sludge as inoculum. Granules first appeared on Day 9 after startup and quickly grew to become the dominant biomass in the reactor. The phenol loading was then adjusted stepwise to a final value of 2.5 $\mathrm{kg}\mathrm{phenol}{m}^{-3}{d}^{-1}$. At this high loading, phenol was completely degraded and high biomass concentration was maintained in the reactor. The biomass continued to possess a good settling ability, with a sludge volume index of 60.5 $\mathrm{mL}g{\mathrm{SS}}^{-1}$ (SS stands for suspended solids). Granules remained stable, without significant deterioration in granule structure and physiology, even at the maximum phenol loading rate tested. The applied selection pressure enabled the micro-organisms to aggregate into granules, and the compact structure of the aerobic granules served both to retain biomass and protect the microbial cells against the phenol toxicity. High specific phenol degradation rates exceeding 1 $g\mathrm{phenol}g{\mathrm{VSS}}^{-1}{d}^{-1}$ (VSS stands for volatile suspended solids) were sustained up to phenol concentrations of 500 $\mathrm{mg}{l}^{-1}$, and significant rates continued to be achieved up to a phenol concentration of 1,900 $\mathrm{mg}{L}^{-1}$. The phenol-degrading aerobic granules can be exploited to design compact high-rate aerobic granulation systems for the treatment of industrial wastewaters containing high concentrations of phenol and other inhibitory chemicals.

This study evaluated the removal of viable Cryptosporidium parvum oocysts and changes in zeta potential during alum coagulation and sedimentation. Experiments were designed to evaluate oocyst removal and oocyst zeta potential at three initial dissolved organic carbon (DOC) concentrations and a wide range of alum doses and coagulation pH values. The study showed that changes in the initial DOC concentration affected the zeta potential of Cryptosporidium parvum oocysts and the removal of oocysts. Oocysts did not appear to be removed by a charge neutralization mechanism under the conditions used in this research. Sweep flocculation appeared to be the primary removal mechanism at the lowest DOC concentration tested in this study. For the highest DOC concentration tested, optimal coagulation conditions for oocyst removal coincided with optimal coagulation conditions for natural organic matter (NOM) removal, suggesting that NOM played a key role in the interaction between oocysts and the aluminum hydroxide precipitate.

A hybrid model which incorporated a biofilm model into the general dynamic model was developed to predict the effluent quality of a combined activated sludge and biofilm process—Taiwan National Central University Process 1. The system was performed under three different dissolved oxygen (DO) conditions in the oxic tank, including 2.0, 1.0, and 0.5 mg/L. When the DO increased from 0.5 to 2.0 mg/L, the soluble biodegradable substrate $\left(S_S\right)$ and soluble phosphate $\left(P_{O4}\right)$ in the effluent were not significantly influenced. Their removal efficiencies were above 92 and 94%. Ammonia–nitrogen $\left(N_{H3}\right)$ removal efficiency increased from 36 to 83% and nitrate–nitrogen $\left(N_{O3}\right)$ increased from 1.7 to 2.9 mg/L. In biofilm, when the DO was 2.0 mg/L, the active autotrophic biomass $\left(Z_A\right)$ fraction was 15.7% (surface) to 12.9% (substratum). But when the DO was 0.5 mg/L, the $Z_A$ fraction became lower and the fraction was 6.2% (surface) to 3.5% (substratum). The fraction of active nonpoly-P heterotrophic biomass $\left(Z_H\right)$ in the biofilm did not vary significantly, the values were about 28–35%. $Z_I$ decreased as the DO increased. $S_S$ in the biofilm did not vary significantly and was maintained at about 2.0 mg/L. When DO increased, $N_{O3}$ also increased, $N_{H3}$ decreased from 13.1 to 1.8 mg/L in biofilm.

Application of cross-flow microfiltration with and without backpulsing is evaluated for the treatment of dilute primary sewage effluent simulating combined sewer overflow wastewater. Four alpha alumina ceramic membranes of various pores sizes $(0.2-5.0\mu m)$ were tested to understand the impact of cross-flow velocity and transmembrane pressure on the permeate water quality and flux rate. The 0.2 and $0.8\mu m$ membranes produced a permeate water quality that is likely to be suitable for surface water discharge. The combination of permeate chemical and biological water quality and long-term flux rates suggest that a $0.2\mu m$ membrane would be the most appropriate membrane for the treatment of combined sewer overflow wastewater within sewersheds.

New polyethersulfone (PES) based membranes for ultrafiltration (UF) were developed by blending a surface-modifying macromolecule (SMM) in the casting solution, in an attempt to minimize the impact of fouling. Fouling was evaluated using concentrated Ottawa River water (CORW), either unfractionated or fractionated via UF. These membranes also included some polyvinylpyrrolidone (PVP), a pore forming additive. A statistical analysis was conducted to evaluate the impact of some variables on the treatment of the surface water. The independent variables included PVP/PES ratio in the casting solution, with and without SMM, and the nature of the feed CORW [low molecular weight (LMW) fraction, unfractionated, high molecular weight (HMW) fraction]. The performance variables studied were total organic carbon (TOC) removal, the foulant accumulation at the membrane surface after filtration, the flux reduction, and the final permeate flux. The most important variable was the feed water. Filtration of LMW had a higher final flux, less fouling, but slightly lower TOC removal. The SMM did not significantly impact the membrane performance. TOC removal was high, compared with results reported in the literature for UF membranes.

With the recent emergence of endocrine disrupting compounds as an important potable drinking water and reclaimed wastewater quality issue, the removal of two estrogenic compounds (17β-estradiol and fluoranthene) by nanofiltration and ultrafiltration membranes was investigated. A less hydrophobic organic compound model species [parachlorobenzoic acid (PCBA)] was tested. 17β-estradiol (E2), fluoranthene, and PCBA were applied to the membrane in the presence and absence of natural organic matter (NOM). Both batch adsorption and dead-end stirred-cell filtration experiments indicated that adsorption is an important mechanism for transport/removal of relatively hydrophobic compounds, and is related to the octanol-water partition coefficient $\left(K_{\mathrm{OW}}\right)$ values. All filtration measurements were performed approximately the same permeate flow rate in order to minimize artifacts from concentration polarization varied with different hydrodynamic operating conditions at the membrane interface. The percent removal by dead-end stirred-cell filtration ranged from 10 to >95% depending upon membrane pore size/hydrophobicity and presence/absence of NOM at an initial concentration ranging from 0.1 to 0.5 μM. Additional batch adsorption experiments with radio-label ${(}^{3}H)$ E2 at lower concentrations ranging 0.025 to 5 nM showed that E2 removal due to adsorption was independent of its initial concentration. Adsorption occurs both on the membrane surface and interior membrane pore surfaces. However, adsorption was insignificant for PCBA $(\log K_{\mathrm{OW}}=2.7)$, but removal presumably occurred due to electrostatic exclusion. Partition coefficients $\left(\log K\right)$ of 0.44 to 4.86 measured in this study increased with $\log K_{\mathrm{OW}}$ and membrane pore size.

The effect of mechanical deformation on the permeation of methylene chloride (MEC), trichloroethylene (TCE) as well as mixtures thereof through linear low-density polyethylene (LLDPE) geomembranes was studied using a new experimental technique. A total of fifty experimental conditions involving five different deformations, five different concentrations and two types of LLDPE geomembranes were evaluated following a full factorial experimental design. Mixtures of TCE and MEC (0.66, 0.50, and 0.34 volumetric fraction) were tested through geomembranes elongated uniaxially (10% and 20%) as well as in the biaxial mode $(10\%\times 10\%\mathrm{and}20\%\times 20\%)$. The breakthrough times for the permeation of TCE and MEC decreased with elongation for both types of geomembranes. A reduction in breakthrough times between 38 and 45% was observed for the permeation of MEC and TCE though geomembranes elongated $20\%\times 20\%$ in the biaxial mode compared to the nonelongated specimens. Evidence of stress-enhanced transport was also observed as the steady-state permeation rates of MEC increased between 200 and 300% where geomembranes were elongated $20\%\times 20\%$ in the biaxial mode compared to the nonelongated samples. Enhanced transport of MEC was also noted during the permeation of the MEC–TCE mixtures.

The treatment performance of sequential heterotrophic and autotrophic denitrification process was evaluated using synthetic wastewaters containing high nitrate concentrations. The effluents from two sequentially connected reactors, for heterotrophic denitrification and sulfur-based autotrophic denitrification, were analyzed for more than 200 days. Experimental results indicated that higher than 95% of the nitrate removal could be achieved with volumetric nitrate loading rates of 2.16, 3.24, and 4.32 $\mathrm{kg}/m^{3}d$. The maximum denitrification rates, with 1,000 mgN/l influent nitrate concentrations, for the heterotrophic and sulfur-packed autotrophic reactors, were found to be 2.47 and 3.61 $\mathrm{kg}/m^{3}d$, respectively. A sequential heterotrophic and autotrophic denitrification process is considered a good alternative for the sole autotrophic denitrification process, providing excellent nitrate removal, especially for nitrate-rich wastewaters with very low organic contents.

Dynamic responses of the blanket in full-scale flat-bottom type floc blanket clarifiers at the PingTsan Water Works, Taiwan Water Supply Corporation, were monitored given a step-change in coagulant (polyaluminum chloride, PACl) dosage. The blankets in the clarifiers were easily washed out using the conventional coagulation-clarification process (the “single-stage process”), seriously threatening drinking water quality. Consequently, the PingTsan Water Works included a pretreatment stage before the single-stage process to enhance treatment efficiency. The performance of this full-scale “two-stage process” for treating high-turbidity storm water was monitored on November 9 to 10, 2000. The two-stage process achieved a stable blanket and good quality clarified water that was insensitive to variation in raw water turbidity or PACl dose. Pilot tests were also conducted on October 6 to 7, 2001 to reveal performance differences between the single-stage and two-stage processes in dealing with high-turbidity water. The single-stage process yielded a blanket that was sensitive to PACl change. Not only was the produced blanket easily washed out when the PACl dose was step-decreased, it was also slow to recover when the chemical dosage was returned to its original value. The blanket yielded by the two-stage process was more robust to low coagulant dose, and recovered more easily when coagulant supply was increased. Applying the two-stage process to achieve the same effluent quality from single-stage process could significantly reduce total PACl dosage.

Urban activities, infrastructure, transportation, and vehicle/infrastructure interactions are sources of metals and particulates in the built environment. These constituents are dry deposited in surrounding aqueous, soil, or snow environments on a continual basis, wet deposited during rainfall–runoff or snowmelt events, and partition between dissolved, colloidal, and particulate phases. Once transported into the porous matrix of snow, particulates, and metals may remain in the matrix for residence times measured in days, potentially resulting in metal partitioning to the particulate-bound phase. This study examined snowmelt particulate (granulometric) and metal data from 10 similar urban land use sites separated by $26\mathrm{km}$. Results indicate a power-law relationship between granulometric indices [mass or surface area (SA)] and particulate-bound metal mass can be established for particulates of similar granulometry, land-use conditions, loadings, and exposure. Power law models (PLMs) were developed to relate granulometric mass, particle number density, total SA and particulate-bound metal mass as a function of the sediment $\left(>75\mu m\right)$ and settleable $(75-25\mu m)$ size gradation from ${4750}^{+}\mathrm{to}25\mu m$. Results indicate that a calibrated and physically based cumulative PLM, $M^{\mathrm{Me}}=\alpha (X/R{)}^{\beta }$ can predict metal mass $\left(M^{\mathrm{Me}}\right)$ from granulometric mass $\left(X\right)$ or from SA, for a specific metal. Formulation of a predictive relationship is advantageous given the relative economy of measuring granulometric indices, from which calibrated relationships between mass and particulate-bound metal mass can be established, as compared to the expense of conventional measurement of metal mass across the size gradation. The study was further motivated based on the potential application of a PLM as a predictive tool utilized with structural controls such as particle-separation unit operations, nonstructural source controls, and mass trading or mass offsetting protocols designed to target portions of the particulate gradation where the predominance of the metal mass is associated.

In October 2001, $\sim 0.2\mathrm{mol}$ of $S{F}_6$ was injected into the upper Hudson River, a modified natural channel with multiple dams, at Ft. Edward, N.Y. The tracer was monitored for 7 days as it moved $\sim 50\mathrm{km}$ downriver. The longitudinal evolution of the tracer distribution was used to estimate one-dimensional advection $(9.0\pm 0.2\mathrm{km}{d}^{-1})$ and dispersion $(17.3\pm 4.0m^2{s}^{-1})$ along the river axis. Comparison of these results to tracer studies on channels without dams suggests that dams reduce longitudinal dispersion below the value expected in a natural channel with the same discharge. $S{F}_6$ loss through air–water gas exchange along the river and at two dams ($10.7m$ combined height) was estimated by observing decay in peak concentration. Losses at dams (approximately 50% per dam) were dominant. The estimated gas exchange at dams was compared to a simple model adapted from those available in literature. Small amounts of tracer were trapped in a canal segment ($\sim 5\mathrm{km}$ long) that parallels the river, where advection and dispersion were sharply reduced.

In this study, a three-dimensional mathematical model for simulating the transport of dissolved contaminants originating from an elliptic-shaped coal tar pool in homogeneous saturated porous media is developed. The methodology of the solution is based on a semianalytical approach that assumes the contaminant source input can be represented by the superposition of a series of consecutive short dissolution pulses. The model accounts for possible solidification of polycyclic aromatic hydrocarbon compounds as the coal tar pool dissolves. A circular-shaped synthetic coal tar pool consisting of 22 components is used for model simulation. Simulations show that even after 130 years of dissolution, the coal tar pool remains a potential groundwater pollution threat despite a significant reduction in overall pool volume.

The long-term disposal of ash from brown coal combustion requires a thorough understanding of the geochemical controls on leachate quality. The geochemistry of leachate in ash generated from the combustion of coal in the Latrobe Valley region of Victoria, Australia, has been studied in the field and laboratory. The field studies, conducted over 14 months, showed active leaching and changes in leachate chemistry in the ash with mobilization of some trace elements. A further series of laboratory columns demonstrated similar leaching dynamics. Geochemical modeling indicated that both sulfate and carbonate minerals are the most likely solubility-controlling mineral phases in the ash. For regularly detected trace elements, such as As, Ba, and B but particularly Mo, Se, and Sr, the trends suggest that adsorption and coprecipitation controls are also important. The overall approach adopted in this paper has enabled a more realistic assessment of the controlling processes for solute transport during the active leaching phase of ash disposal, thereby improving long-term environmental management.

An effective procedure for stabilization/solidification of industrial wastewater treatment sludge has been developed and verified. The procedure consists of economically advantageous sludge solidification by fluidized bed combustion ash with an addition of highly porous carbon black as an adsorption additive, and subsequent creation of an asphalt coating on the surface of the solidified sludge by means of aqueous asphalt emulsion. The carbon black addition enables the reduction of binder dosage needed for solidification of the sludge and simultaneously reduces the leachability of organic compounds. The creation of an asphalt coating effectively prevents leaching of all pollutants observed. The method also reduces the infectiousness of the stabilized/solidified sludge.

An artificial neural network (ANN) model is developed to study the correlation of data with reference to various wastewater pollution parameters (biochemical oxygen demand, chemical oxygen demand, suspended solids, $N{H}_4$, $P{O}_4$) using two scales of experiments viz. column lysimeter and a pilot soil aquifer treatment (SAT) system for wastewater renovation in India. A unique feature of the study is that the primary treated wastewater was directly applied to SAT system for renovation in contrast to the secondary treated effluent used in most of the other studies that have been reported. The analysis of data using ANN as a tool indicates that the column lysimeter data are useful for design of SAT systems and it is possible to predict the effluent quality for SAT system based on the inputs from lysimeter experiments. The study highlights the utility of column lysimeter studies for evolving design parameters for a full-scale SAT system thereby obviating the need for pilot SAT studies which are site specific, time consuming, and expensive. Thus, the study suggests that the experimental data from lysimeter studies at a particular site can be used to predict performance of field-scale SAT systems without going in for actual experimentation. Further, the field data from one site could be utilized for design of SAT systems at other locations provided the climatic and hydrogeological conditions viz. soil matrix characteristics and wastewater characteristics, etc., are similar.

Contaminated dredged material is often placed in confined disposal facilities (CDFs) designed and managed to control environmental impacts of the disposed sediment. This note presents equations for use in a screening procedure to evaluate the impact of a CDF on groundwater. The hydrologic evaluation of leachate production and quality model was used to simulate leachate production and transport through the foundation considering a range of foundation soil characteristics and contaminant properties. The model results were used to develop predictive equations of contaminant attenuation and travel time in the foundation soils. When used with equations to predict dispersion in the aquifer, contaminant exposures at receptor locations can be predicted, which is essential in leachate screening applications. The approach does not consider degradation or permanent sequestration of contaminants. Therefore, the procedure is conservative in that it may overestimate actual leachate concentrations and underestimate actual travel times.

The effects of liquid $C{O}_2$ injection on the viability of Cryptosporidium parvum oocysts were evaluated. A laboratory study was designed to test the effects of saturated $C{O}_2$, freeze–thaw cycles and different freezing protocols on C. parvum oocysts in aquifer material. Oocysts were exposed to a saturated solution of $C{O}_2$ at room temperature for 1-, 4-, 8-, and $12-h$ intervals and their viability was compared with controls. One- and three-cycle freeze–thaw experiments on oocyst survival were conducted. Inactivation of oocysts was assessed for: (1) rapid freezing and rapid thawing and (2) gradual freezing and rapid thawing. Exposure to 1 atm of $C{O}_2$ in water at room temperature had a negligible effect on oocyst viability. Average oocyst viability after the one- and three-cycle freeze–thaw experiments was 24.7 and 2.7%, repsectively. The average oocyst viability associated with the rapid freeze–thaw and gradual freeze–thaw experiments was 11.3 and 26.2%, respectively. Freezing associated with injection of liquid $C{O}_2$ into aquifers would be the factor inactivating oocysts; to cause a 3-log decrease in oocyst viability multiple injections may be required.

The Hsinchu Science-based Industrial Park (HSIP) is the main manufacturing base of “high-tech” commodities of Taiwan. The treatment of wastewater of HSIP produces hard-to-dewater sludge, at a rate of 80 Mg/day, which is resistant to chemical conditioning, whose disposal is costly. The use of chemical flocculation and physical conditioning, including heating and freezing and thawing, on the dewaterability of HSIP sludge was examined in this Note. The dewaterability of the original sludge was poor, and neither chemical flocculation nor thermal heating enhanced its dewatering. However, the freezing and thawing could release up to 83% of moisture from the sludge body; in line with this occurrence, the settleability and filterability of the sludge were considerably enhanced. The ice front developed during freezing, which could destroy the floc network, release the interstitial water, and might correspond to the successful conditioning using freezing and thawing.