Journal of Environmental Engineering

The operating conditions of this study are close to the typical operating conditions of flue gas desulfurization system in coal-fired power plants. The aim of this study is to investigate the absorption kinetics of ${\mathrm{SO}}_2$ and NO from simulated flue gas into an aqueous solution of acidic sodium chlorite using a bench-scale spraying column. The range of absorption rates measured in this study is between $1.91\times {10}^{-11}$ and $9.59\times {10}^{-10}\mathrm{mol} s^{-1} {\mathrm{cm}}^{-2}\text{.}$ The range of rate constants measured in this study is between $1.32\times {10}^7$ and $1.21\times {10}^8(L {\mathrm{mol}}^{-1}{)}^{1.9} s^{-1}\text{,}$ and the average rate constant is $6.16\times {10}^7(L {\mathrm{mol}}^{-1}{)}^{1.9} s^{-1}\text{.}$ The activation energy and frequency factor are 129 Kcal/mol (53.97 KJ/mol) and $6.93\times {10}^{16}\left[\right(L/\mathrm{mol}{)}^{1.9}/s]\text{,}$ respectively.

The objective of this study was to evaluate correlations between annual average daily traffic (AADT) and storm water runoff pollutant concentrations generated from California Department of Transportation (Caltrans) highway sites. Analyses of data collected from the Caltrans four-year (1997–2001) highway runoff characterization program revealed that, in general, pollutant concentrations from urban highways were higher than those found from nonurban highways. For a limited number of pollutants, however, the concentrations from nonurban highways were found to be higher than the concentrations from urban highways. No direct linear correlation was found between highway runoff pollutant event mean concentrations and AADT. However, through multiple regression analyses, it was shown that AADT has an influence on most highway runoff constituent concentrations, in conjunction with factors associated with watershed characteristics and pollutant build-up and wash off. The other noticeable factors shown to influence the accumulation of pollutants on highways were antecedent dry period, drainage area, maximum rain intensity, and land use.

The purpose of this study is to develop a kinetic model that links $O_3$ decomposition reactions from the TFG ozone decay model with recognized ${\mathrm{Br}}^{-}$ oxidation reactions, secondary •OH reactions, and $H_2{O}_2$ reactions in order to improve $O_3$ decay and bromate formation prediction capabilities under multiple water quality conditions. The model was compared with experimentally measured ozone decomposition and final bromate concentration data sets provided by two researchers. The data sets included varying pH (6.5–8.5), initial hydrogen peroxide (0–1 mM), and initial bromide concentration (0.1–1 mM). Model verification was carried out by sensitivity analysis of the rate constants and then optimization of the most sensitive rate constants using the method of least squares. Model predicted ozone decay data was analyzed and compared with measured ozone decay data using R-squared statistic for linear regression model. The model predicted final bromate concentration is analyzed by comparing it with the residual Δ(%) between experimental and model results. The TFG model was effectively tested for multiple data sets and it was found that model prediction was a success both for ozone decay (regression coefficients >0.95 for all experimental conditions but one) and bromate prediction with residual of less than 100% for all experimental conditions except low peroxide dose (<20 μm).

The anaerobic biodegradability of mixtures of phenolic compounds was studied under continuous and batch systems. Continuous experiments were carried out in up-flow anaerobic sludge bed (UASB) reactors degrading a mixture of phenol and p-cresol as the main carbon and energy sources. The total chemical oxygen demand (COD) removal above 90% was achieved even at organic loading rates as high as 7 kg COD/m³/day. Batch experiments were conducted with mixtures of phenolic compounds (phenol, p-cresol, and o-cresol) to determine the specific biodegradation rates using unadapted and adapted anaerobic granular sludge. Phenol and p-cresol were mineralized by adapted sludge with rates several orders of magnitude higher than unadapted sludge. Additionally, an UASB reactor was operated with the mixture phenol, p-cresol, and o-cresol. After 54 days of operation, 80% of o-cresol (supplied at 132 mg/L) was eliminated. The phenol biodegradation was not affected by the presence of o-cresol. These results demonstrate that major phenolic components in petrochemical effluents can be biodegraded simultaneously during anaerobic treatment.

It is known that in well-operated anaerobic systems the majority of the residual chemical oxygen demand (COD) present in the effluent is due to soluble microbial products (SMP) generated during treatment. SMP production is affected by many factors, and this study investigated the effect of nutrient deficiency on SMP production in anaerobic chemostats fed on glucose as the sole carbon source. The results showed that under steady-state conditions the $\mathrm{SMP}/{\mathrm{COD}}_{\mathrm{out}}$ ratio was as high as 95% and the normalized SMP production $(\mathrm{SMP}/S_o)$ averaged 3%. During nutrient deficiency the $\mathrm{SMP}/{\mathrm{COD}}_{\mathrm{out}}$ ratio averaged 45% indicating that the importance of SMP in the effluent was reduced due to the enhanced production of VFAs. Nevertheless, under such stressed conditions the normalized production of SMP $(\mathrm{SMP}/S_o)$ increased reaching up to 37%. Analysis of extracellular polymers (ECP) indicated that ${\mathrm{ECP}}_c$ production was enhanced after nutrient cessation and chemical analyses of the effluent suggest that most of the SMP was not protein- or carbohydrate-like material. DNA analysis indicates that part of the SMP produced during nutrient deficiency might be due to enhanced cell lysis, although some organics might have been deliberately excreted to scavenge metal nutrients. Biochemical methane potential (BMP) assays showed that the lack of N and P resulted in the highest SMP production which might have been released to dump electrons that could not be used in cell synthesis due to the lack of these macronutrients.

A single unit anaerobic granular bed baffled reactor (GRABBR) is proposed as an alternative to a separately operated two-phase anaerobic digestion system. This overcomes the problems related to wastewater treatment at high loading rates which usually results in accumulation of intermediate acid products, and consequently inhibits methanogenesis. This study was carried out to evaluate the stability of a five compartment GRABBR system when treating synthetic glucose wastewater at various operational conditions. The reactor was started with volumetric organic loading rate (OLR) of 1 kg chemical oxygen demand $\left(\mathrm{COD}\right)/m^3 \mathrm{day}\text{,}$ equivalent to 120 h hydraulic retention time (HRT), and loading rates were gradually increased at suitable intervals to up to 20 kg $\mathrm{COD}/m^3 \mathrm{day}$ (6 h HRT). At steady state, the overall soluble COD (SCOD) removal was over 95% under all applied loading conditions. At lower loadings, the reactor operated as a completely mixed system, and most of the treatment was achieved in the first compartment. At higher loadings, the entire system transformed into different phases, acidogenesis being dominant near the influent point, whilst methanogenesis was the main activity in the compartments near the effluent point. Granule breaking and flotation was observed in the acidogenic zone, whilst the methanogenic zone retained its original granular form. High assimilation rate of influent nitrogen was observed in the first compartment with the formation of nongranular biomass, identified as Klebsiella pneumoniae. The success of GRABBR as a single unit two-phase anaerobic digestion system could save the cost of an extra unit traditionally employed to achieve similar goals in treatment of high strength wastewaters.

The Western Treatment Plant (WTP) is one of the largest treatment plants in Australia treating more than 500 ML of sewage per day, discharging treated effluent to Port Phillip Bay in Victoria, Australia. The Port Phillip Bay Environmental Study (1992–1996) concluded that there was a need to reduce nitrogen loads from WTP to lower the risk of eutrophication, especially during winter when grass filtration was in operation. Therefore, in 1997, Melbourne Water initiated a pilot study to investigate the effectiveness of grass filtration for polishing wastewater that had received prior lagoon treatment. The study involved field monitoring of seven trial grass filtration bays at the WTP for hydraulic and water quality data from mid-May to early-October 1997. The results of the pilot study revealed that the removal rates of these nutrients were higher during the first half of the trials than during the second half. The results also showed that the removal rates of nutrients were inversely proportional to the hydraulic loading rates of the bays. A hydraulic loading rate of 40 mm/d was found to be optimal in this pilot study for achieving a balance between wastewater throughput and nutrient removal.

Batch tests and different statistical tools of data analysis were used to re-evaluate the overall effect of soil characteristics and liquid phase composition on the extent of phenanthrene adsorption in complex soil-water systems. The linear isotherm models was capable of adequately describing the equilibrium data under extremely varying conditions of soil type, environmental conditions (pH, temperature, ionic strength) and amendments (surfactant, oil, dispersing agent, glucose). Consistent with existing mechanistic models, the multivariate approach also identified the organic carbon content $\left(f_{\mathrm{oc}}\right)$ of soil as the key parameter controlling the phenanthrene adsorption constant $\left(K_d\right)$ in nonamended systems $(K_{\mathrm{oc}}$ was 17,700 mL/g). From studying the effect of the amendments, two interactions (surfactant-pH and surfactant-oil) and two main effects (surfactant and oil) have been detected. An empirical linear model of $K_d$ as a function of $f_{\mathrm{oc}}\text{,}$ pH, oil content of soil, and surfactant dose was developed for the range of conditions studied. The proposed model and modeling approach can be adapted to other types of contaminants or variables for specific natural and engineered systems.

Sorption and extractability of naphthol and naphthol polymerization products (NPP) were evaluated in two surface soils. NPP were generated by the addition of horseradish peroxidase and $H_2{O}_2$ to naphthol solutions in contact with the surface soils. While NPP retention on the forest soil was lower compared to the parent naphthol, no difference in sorption of naphthol and NPP was observed in the agricultural soil. The agricultural soil retained more naphthol and NPP than the forest soil. The NPP sorption behavior noted in this study was in contrast to that of phenol polymerization products observed by other researchers. The presence of phenol and 2,4-dichlorophenol as cosolutes had no significant impact on naphthol or NPP retention on the two soils, and naphthol was more easily extracted from both soils whenever phenol was present as a cosolute. Characterization of the naphthol polymerization products using reverse-phase high-pressure liquid chromatography and octanol-water partitioning indicated that significant fractions of the water-soluble and insoluble NPP were comprised of oligomers that were more polar than the parent 1-naphthol. This decrease in polarity upon polymerization is believed to have been responsible for the NPP retention and binding behavior observed in this study.

In the present paper, the behavior of municipal solid waste incinerator ash in cement-based systems was simulated by spiking experiments on portland cement making use of pure compounds, including ${\mathrm{MgCl}}_2\text{,}$ $K_2{\mathrm{SO}}_4\text{,}$ $\mathrm{Zn}({\mathrm{NO}}_3{)}_2\text{,}$ and ${\mathrm{NaNO}}_2\text{,}$ which were selected based on the findings from previous investigation. A $2^{4-1}$ fractional factorial design was used to arrange the program of experiments. The evolution of physical and mechanical properties as well as acid neutralization capacity with curing time was studied with the aid of statistical analysis. Based on the results from the present work, a model was developed for prediction of unconfined compressive strength and buffering capacity of incinerator ash—portland cement mixtures. The good agreement between predicted and measured values indicated that the behavior of incinerator ash in cementitious systems is largely to be ascribed to the four selected compounds.

Wastewater emanating from color photograph processing units is usually in small quantities (5–20 L per day) and contains high concentrations of recalcitrant organic compounds. Disposal of such highly recalcitrant wastewater into a public sewer may result in an inhibiting effect on biological treatment system of a sewage treatment plant and thus these persistent organics can escape to receiving water bodies. A continuous full-scale treatment unit for such a small quantity of wastewater is not a viable option, economically and technically. In this study, a small batch type of an electrochemical reactor has been utilized to investigate the feasibility of electrochemical treatment of wastewater from a color photograph processing unit. The treatability studies were conducted using cast iron electrode. It was found that the cast iron electrode was efficient in removing both chemical oxygen demand and biochemical oxygen demand to the levels that meet the standards for discharge to surface water and public sewer. The energy consumption to meet the standards for sewer disposal was less compared to that of surface water disposal. The electrochemical reactor was found to be cost effective in both installation and operation for meeting the sewer disposal standards. It was concluded that the wastewater could be partially treated (pretreatment) electrochemically to meet the standard for sewer disposal rather than that of surface water disposal.

Color removal from cotton textile processing wastewater by addition of powdered activated carbon (PAC) into a lab-scale activated sludge system was examined. The activated sludge system was continuously operated in different sludge ages (SRTs) and hydraulic retention times (HRTs). $\mathrm{SRT}=30d$ and $\mathrm{HRT}=1.6d$ operation resulted in up to 36% color removal and 94% COD removal. PAC was added 100, 200, and 400 mg/L into the activated sludge system under these operating conditions. The results indicated that 100 mg/L PAC was sufficient to remove the maximum color measured (up to 50 m⁻¹) from the wastewater. The addition of PAC did not affect chemical oxygen demand (COD) removal significantly. Oxygen uptake rate (OUR) tests were also performed to investigate the microbial activities controlling the system performance. The average OUR was 74.1 mg/L/h without PAC addition while it was 70 mg/L/h with PAC addition. Adsorbable organic halogens of the effluent wastewater decreased from 400 to 50 μg/L with the addition of PAC. Toxicity dilution factor decreased from 2 to 1.5 with the PAC addition into the activated sludge system.