Roger Babcock

Approximately one-quarter of housing units in the United States are not connected to centralized, publicly owned wastewater treatment works and instead operate their own cesspools or septic tanks that provide only partial treatment. A study was conducted in which a ...

A nine-month in situ bioremediation study was conducted in Makua Military Reservation (MMR) in Oahu, Hawaii (USA) to evaluate the potential of molasses to enhance biodegradation of royal demolition explosive (RDX) and high-melting explosive (HMX) contaminated soil below the root zone. MMR has been in operation since the 1940's resulting in subsurface contamination that in some locations exceeds USEPA preliminary remediation goals for these chemicals. A molasses-water mixture (1 : 40 dilution) was applied to a treatment plot and clean water was applied to a control plot via seven flood irrigation events. Pore water samples were collected from 12 lysimeters installed at different depths in 3 boreholes in each test plot. The difference in mean concentrations of RDX in pore water samples from the two test plots was very highly significant (p < 0.001). The concentrations differences with depth were also very highly significant (p < 0.001) and degradation was greatly enhanced at depths from 5 to 13.5 ft. biodegradation was modeled as first order and the rate constant was 0.063 per day at 5 ft and decreased to 0.023 per day at 11 ft to 13.5 ft depth. Enhanced biodegradation of HMX was also observed in molasses treated plot samples but only at a depth of 5 ft. The difference in mean TOC concentration (surrogate for molasses) was highly significant with depth (p = 0.003) and very highly significant with treatment (p < 0.001). Mean total nitrogen concentrations also differed significantly with treatment (p < 0.001) and depth (p = 0.059). The molasses water mixture had a similar infiltration rate to that of plain water (average 4.12 ft per day) and reached the deepest sensor (31 ft) within 5 days of application. Most of the molasses was consumed by soil microorganisms by about 13.5 feet below ground surface and treatment of deeper depths may require greater molasses concentrations and/or more frequent flood irrigation. Use of the bioremediation method described herein could allow the sustainable use of live fire training ranges by enhancing biodegradation of explosives in situ and preventing them from migrating to through the vadose zone to underlying ground water and off-site.

ABSTRACT Bioaugmentation can enhance the removal of hazardous wastes or improve nutrient removal in activated sludge processes. Bioaugmentation processes can be classified into several major approaches, such as adding enriched cultures from commercial “off-site” sources; adding cells produced from other treatment plants or “on-site” reactors, or growing additional biomass with the return activated sludge. This paper quantifies the effectiveness of bioaugmentation processes based on experimental results and verified models. In the first part of the paper we present our lab-scale experiments and simulations with bioaugmentation to enhance the removal of an aromatic compound. Based upon a similar model, the second part of this paper compares different on-site bioaugmentation approaches to improve nitrogen removal. The results suggested that using enricher reactor with return sludge would likely be more useful at lower temperature and required less reactor volume while the enricher-reactor approach would likely be more advantageous in the presence of inhibitory compound(s).

Green roofs reduce runoff from impervious surfaces in urban development. This paper reviews the technical literature on green roof hydrology. Laboratory experiments and field measurements have shown that green roofs can reduce stormwater runoff volume by 30 to 86%, reduce peak flow rate by 22 to 93% and delay the peak flow by 0 to 30 min and thereby decrease pollution, flooding and erosion during precipitation events. However, the effectiveness can vary substantially due to design characteristics making performance predictions difficult. Evaluation of the most recently published study findings indicates that the major factors affecting green roof hydrology are precipitation volume, precipitation dynamics, antecedent conditions, growth medium, plant species, and roof slope. This paper also evaluates the computer models commonly used to simulate hydrologic processes for green roofs, including stormwater management model, soil water atmosphere and plant, SWMS-2D, HYDRUS, and other models that are shown to be effective for predicting precipitation response and economic benefits. The review findings indicate that green roofs are effective for reduction of runoff volume and peak flow, and delay of peak flow, however, no tool or model is available to predict expected performance for any given anticipated system based on design parameters that directly affect green roof hydrology.

A biodegradable dissolved organic carbon (BDOC) method has been developed and used to analyze secondary- and advanced-treated wastewater effluents and to investigate correlations between residual organic content and the solids retention time (SRT). Conventional biochemical oxygen demand (BOD) bottles and a 28-day incubation period were used. Secondary wastewater effluents from Hawaii were found to contain between 9.0 and 14.0 mg/L of dissolved organic carbon (DOC), of which 23 to 35% was biodegradable in the 28-day BDOC test (from a survey of nine treatment plants). Bench-scale, continuous-flow activated-sludge biological reactors treating synthetic wastewater were operated at SRTs between 2 and 15 days, and effluent BDOCs were determined. A good BDOC prediction equation was developed that incorporates the initial DOC, the DOC remaining after 5 days, and the SRT of the system from which the sample originated. This equation can be used to determine the BDOC value using data that can be obtained during a conventional 5-day BOD test. The determined equation was found to be appropriate for some of the full-scale wastewater effluent survey data.

... Page 2. Khan e? al. ... the Las V?rgenes Municipal Water District; Glendale WWTP, Glendale, California, 20 mgd, operated by the Los Angeles Bureau of Sanitation (LABS); Tillman WWTP, Van Nuys, California, 65 mgd, operated by the LABS; Orange County WWTP No. ...

Ozone mass transfer in reclaimed water was evaluated at pilot scale to determine mass-transfer characteristics and reaction kinetics and to assess the use of oxygen as a surrogate to measure this process. Tests were conducted in a 40-L/min pilot plant over a 3-year period. Nonsteady-state mass-transfer analyses for both oxygen and ozone were performed for superficial gas flow rates ranging from 0.13m/min to 0.40m/min. The psi factor, which is the ratio of volumetric mass-transfer coefficients of ozone to oxygen, was determined. The decrease in oxygen transfer rate caused by contaminants in reclaimed water was only 10 to 15% compared to tap water. A simple mathematical model was developed to describe transfer rate and steady state ozone concentration. Ozone decay was modeled accurately as a pseudo first-order reaction between ozone and ozone-demanding materials.

... the HPLC standard curve regres-sion lines and the recovery efficiency of the extraction procedure as described previously (Babcock, 1991 ... There were eight flasks; the original 1NA enrichment culture (data not shown), the IAN enrichment culture (Figure 3), the 1SN enrichment ...

A 15-week treatability study was conducted in a greenhouse to evaluate the potential effects of molasses on the bioremediation and phytoremediation potential of Guinea Grass (Panicum maximum) for treating energetic contaminated soil from the open burn/open detonation area of the Makua Military Reservation, Oahu, HI (USA). The energetics in the soil were royal demolition explosive (RDX) and high-melting explosive (HMX). Among the 6 treatments employed in this study, enhanced removal of RDX was observed from treatments that received molasses and went to completion. The RDX degradation rates in treatments with molasses diluted 1:20 and 1:40 were comparable suggesting that the lower dose worked as well as the higher dose. Treatments without molasses degraded RDX slowly and residuals remained after 15 weeks. The bacterial densities in molasses-treated units were much greater than those without molasses. Phytoremediation alone seems to have little effect on RDX disappearance. For HMX, neither bioremediation nor phytoremediation was found to be useful in reducing the concentration within the experimental period. The concentrations of nitrogen and phosphorous in the soil did not change significantly during the experiment, however, a slight increase in soil pH was observed in all treatments. The study showed that irrigating with diluted molasses is effective at enhancing RDX degradation mainly in the root zone and just below it. The long term sustainability of active training ranges can be enhanced by bioremediation using molasses treatments to prevent RDX deposited by on-going operations from migrating through the soil to groundwater and off-site.

Elevated concentrations of estrogens in natural waters pose a significant threat to public health and aquatic ecosystems. Both natural (estrone, 17β-estradiol and estriol) and synthetic (17α ethynylestradiol) estrogens, ubiquitous in wastewater effluents and receiving waters, have been shown to affect the endocrine system of human and aquatic life. The effects vary from cancer to sex reversals at levels as low as parts per trillion in sensitive organisms. Separation of urine, which constitutes only about 1% of domestic sewage and contains nearly all of the excreted estrogens, potentially offers an energy-efficient way to contain and then treat these chemicals. With a capital expense of $2100 and operation and maintenance costs of $69 per year for a urine diverting toilet system, a family in the USA can realize estimated savings of $101 per year in energy, water, and nutrients and a decrease of 100 kg in greenhouse gas emissions. To remove 99% of estrogenicity in discharged waters would require approximately 12 kW h per year using continuous electrodialysis followed by ozonation (O(3)) of source separated urine. To achieve the same results by adding O(3) treatment after activated sludge at existing municipal wastewater treatment plants would require 23 kW h per year. From an energy standpoint it makes sense to practice source separation and treatment of urine to limit estrogen discharges into the environment.

Approximately one-quarter of housing units in the United States are not connected to centralized, publicly owned wastewater treatment works and instead operate their own cesspools or septic tanks that provide only partial treatment. A study was conducted in which a ...

... Roger W. Babcock Jr1,*, Jos Malda2 and JoAnn C. Radway3 1Civil Engineering Department, University of Hawaii, Honolulu, HI ... The efficiency of light transmission per unit volume ... Livansky (1990) reported mass transfer coefficients corresponding to KLa val-ues of 5 to 8 h−1 at ...