Aerated Rock Filters for Enhanced Ammonia and Fecal Coliform Removal from Facultative Pond Effluents

Rock filters used to treat effluents from waste stabilization ponds do not remove ammonia as they are anoxic. A pilot-scale aerated rock filter was investigated, in parallel with an unaerated control, over an 18-month period to determine whether aeration provided conditions within the rock filter for nitrification to occur. Facultative pond effluent containing ～ 10?mg NH4–N/L was applied to the filters at a hydraulic loading rate of 0.15?m3/m3?day during the first 8?months and at 0.3?m3/m3?day thereafter. The results show that the ammonia and nitrate concentrations in the effluent from the aerated filter were <3 and ～ 5?mg?N/L, respectively, whereas the ammonia concentration in the effluent from the control filter was ～ 7?mg?N/L. Fecal coliforms were reduced in the aerated filter to a geometric mean count of 65?per?100?mL; in contrast the effluent from the control filter contained 103–104 fecal coliforms per 100?mL. Aerated rock filters are thus a useful land-saving alternative to aerobic maturation ponds.     

Thermal Treatment of Waste Activated Sludge Using Liquid Boiling

In this work we investigated the use of a short time, low superheat boiling process to treat biological sludge. The treated sludge would exhibit a deteriorated filterability, and a marked increase in soluble organics content. A large portion of extracellular polymers was released from the solid phase by boiling. The microbial density levels of the total coliform bacteria and the heterotrophic bacteria were reduced after treatment. Dilution in sludge concentration could allow more organic compounds to be hydrolyzed and a greater fraction of microbes to be disinfected when compared with the undiluted samples.     

Simultaneous Nitrogen and Phosphorus Removal from High-Strength Industrial Wastewater Using Aerobic Granular Sludge

Aerobic granular sludge technology was applied to the simultaneous nitrogen and phosphorus removal from livestock wastewater that contains high concentrations of nitrogen and phosphorus (TN: 650?mg/L; TP: 125?mg/L). A lab-scale sequencing batch reactor was operated in an alternating anaerobic/oxic/anoxic denitrification mode. Granular sludge was first formed using synthetic wastewater. When livestock wastewater was diluted with tap water, the shape and settleability of aerobic granular sludge were maintained even though livestock wastewater contained suspended solids. Simultaneous nitrification, denitrification, and phosphate uptake were observed under an aerobic condition. However, when nondiluted livestock wastewater was used, the diameter of granular sludge and the denitrification efficiency under an oxic condition decreased. When the concentrations of nitrogen and phosphorus in wastewater increased, hydraulic retention time (HRT) increased resulting in a decrease in selection pressure for granular sludge. Therefore, the sustainment of granular sludge was difficult in livestock wastewater treatment. However, by applying a new excess sludge discharge method based on Stokes’ law, the shape of granular sludge was maintained in spite of the long HRT (7.5?days). To select large granular sludge particles, excess sludge was discharged from the upper part of settled sludge because small particles localized there after settling. Finally, excellent nitrogen and phosphorus removal was accomplished in practical livestock wastewater treatment. The effluent concentrations of NH4–N, NOx–N, and PO4–P were <0.1, 1.4, and 1.2?mg/L, respectively.     

Indicator Bacteria Removal in Storm-Water Best Management Practices in Charlotte, North Carolina

Water quality degradation due to pathogen pollution is a major concern in the United States. Storm-water runoff is an important contributor to the transport of indicator bacteria from urbanized watersheds to nearby surface waters. With total maximum daily loads being established to reduce the export of indicator bacteria to surface waters, storm-water best management practices (BMPs) may be an important tool in treating indicator bacteria in runoff. However, the ability of these systems to remove indicator bacteria is not well established. A study in Charlotte, N.C., monitored nine storm-water BMPs (one wet pond, two storm-water wetlands, two dry detention basins, one bioretention area, and three proprietary devices) for fecal coliform and Escherichia coli (E. coli). A wet pond, two wetlands, a bioretention area, and a proprietary device all removed fecal coliform with an efficiency higher than 50%; however, only the wetlands and bioretention area had significantly different influent and effluent concentrations (p<0.05). For E. coli, only one of the wetlands and the bioretention area provided a concentration reduction greater than 50%, both of which had a significant difference in influent and effluent concentrations (p<0.05). Only one of the nine BMPs had a geometric mean effluent concentration of fecal coliform lower than the U.S. EPA target value, while four of the nine BMPs had geometric mean effluent concentrations lower than the U.S. EPA standard for E. coli. This study showed that some BMPs may be useful for treatment of indicator bacteria; however, other BMPs did not perform well. Because wet, nutrient-rich environments exist in many storm-water BMPs, there is a potential for indicator bacteria to persist in these systems.     

Electrochemical Disinfection of Saline Wastewater Effluent

A laboratory-scale electrochemical (EC) disinfector was used for the disinfection of various wastewater effluents, including saline primary effluent, saline secondary effluent, and freshwater secondary effluent. Such EC disinfection was highly effective for saline effluent with a salinity content of around 8‰. A killing efficiency of 99.9% on total coliform bacteria was achieved for saline secondary effluent with a contact time of less than 10 s and a power consumption rate no more than 0.006?kWh/m3. For primarily treated saline effluent, the same degree of disinfection was obtained with a contact time of less than 20 s and a power consumption of lower than 0.08 kWh/m3. The efficiency of EC disinfection was regulated by both the contact time (t) and current density (Id) applied, and a kinetic function in terms of survival ratio (N/N0) was developed for the saline secondary effluent, i.e., log(N/N0) = ?0.01(Idt)1.87. While EC disinfection is highly applicable for saline effluent, it did not exhibit a similar degree of effectiveness for freshwater sewage effluent, even with a longer contact time and higher power input. Based on the results of the EC disinfection and comparative direct chlorination experiments, it is argued that the main disinfecting action of the EC process may not be electrochlorination. The EC process could produce other short-lived, more powerful germicidal substances that exert the strong killing function within a short contact time.     

Microbiological quality and the inability of proteolytic Clostridium botulinum to produce toxin in film-packaged fresh-cut cabbage and lettuce

The production of toxin by a 10-strain mixture of proteolytic Clostridium botulinum in fresh produce packaged in polyethylene films having high (7,000 cc/m2/24 h; HOTR) and low (3,000 cc/m2/24 h; LOTR) relative oxygen permeability was determined. Shredded cabbage and lettuce inoculated with approximately 10(2) spores/g were placed in bags composed of the two films (1.4 kg/bag), and the bags were then vacuum sealed. Produce was stored at 4, 13, and 21 degrees C for up to 21 (cabbage) or 28 (lettuce) days and analyzed periodically. At each sampling time, the gas composition within the bags, pH of the produce, and microbial populations (total aerobic and anaerobic microorganisms, lactic acid bacteria, psychrotrophic bacteria, and yeasts and molds) were determined. In addition, the presence of botulinal toxin was determined using the standard U.S. Food and Drug Administration mouse bioassay protocol. Bags made of HOTR film prolonged sensory quality of cabbage and lettuce, especially at 13 and 4 degrees C. Packaging material had an effect on the growth of various groups of microorganisms; however, there was not a general trend. For example, lettuce packaged in HOTR bags had higher aerobic microbial populations than that packed in LOTR, but no significant difference (P < or = 0.05) was observed with cabbage. Growth of psychrotrophic bacteria was greater in vegetables packaged in HOTR film while growth of yeasts and molds was not affected by either packaging film. Most differences in microbial populations in produce packaged in LOTR and HOTR films were less than 1 log10 CFU/g. Botulinal toxin was not detected in cabbage or lettuce packaged in either film or stored under any test condition.     

Pilot Plant Study of Simultaneous Sewage Sludge Digestion and Metal Leaching

This research is related to a preindustrial pilot scale study of the performance of the simultaneous sewage sludge digestion and metal leaching (SSDML) process for decontamination and stabilization of sewage sludge. Ten batch tests were carried out in two 4?m3 bioreactors under various conditions of operation. Results indicated that the addition of 1.0 to 1.5?g?S0/L, which is the equivalent of approximately 30 to 50?kg?S0 per tons dry sludge, is sufficient to obtain conditions of acidity (pH<2.5) and oxido-reduction potential greater than 500 mV necessary for an effective solubilization of toxic metals. The final average of metal solubilization in the output sludge during the SSDML process varied in the following ranges: 25–78% Cd, 9–32% Cr, 48–100% Cu, 77–99% Mn, 15–53% Ni, 12–47% Pb, and 66–100% Zn. The N, P, and K contents were also preserved in the decontaminated sludge. Moreover, the use of low concentrations of elemental sulfur makes it possible to obtain decontaminated sludge with a low total sulfur content (1.4–1.5% S) compatible with agricultural use. The suspended solids removal calculated for the SSDML process was slightly lower, (2.5±0.4)% volatile suspended solids per day, than those reached using standard aerobic digestion. Finally, the SSDML process was found to be effective in removing bad odors and in the destruction (99–100%) of indicator bacteria.     

Organic acid dipping of catfish fillets: effect on color, microbial load, and Listeria monocytogenes

Microbiological and color changes of catfish fillets were determined following dip treatment in solutions at 4 degrees C of 2% acetic, citric, hydrochloric, lactic, malic, or tartaric acid. Fillets were inoculated with an eight-strain mixture of Listeria monocytogenes prior to dipping. L. monocytogenes, coliform, and aerobic plate counts and surface pH and Hunter color were measured at 0, 2, 5, and 8 days of storage at 4 degrees C. Acid dipping reduced surface pH and L. monocytogenes, coliform, and aerobic microbial loads. Little microbial proliferation was observed on acid-treated fillets, however, controls had a distinct foul odor and microbial loads in excess of 10(6) CFU/g by day 8. On untreated fillets, L. monocytogenes counts did not increase during storage, perhaps due to competitive inhibition by normal catfish microflora. Hunter color analysis revealed lighter and yellower acid-treated fillets than untreated controls, with malic acid producing the least bleaching. The shelf life of refrigerated fillets increased when fillets were acid dipped. It remains to be established if this enhanced microbial quality also parallels sensory acceptability.     

Anaerobic bacteremia and fungemia in patients undergoing endodontic therapy: an overview

There is not yet a universally accepted protocol for the recovery of microorganisms causing peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD). We prospectively analyzed 343 peritoneal effluent specimens by three protocols: 1) 10 ml of effluent centrifuged and the pellet plated onto blood, MacConkey agars, and into thioglycolate broth (routine method); 2) 5 ml and 10 ml inoculated at the bedside into Bactec 16A and 26A aerobic resin-containing blood culture bottles, respectively; and 3) 5 ml and 10 ml inoculated in the laboratory into Bactec 16A and 26A media, respectively. One hundred and forty (41%) peritoneal effluent specimens had microorganisms recovered, and, of these, 101 were recovered by routine culture compared to 117 (p < .021), 125 (p < .0001), 115 (p < .047), and 116 (p < .032) for bedside-inoculated 16A and 26A and for laboratory-inoculated 16A and 26A, respectively. Bedside-inoculated bottles were not significantly better than laboratory-inoculated bottles, and high-volume bottles were not significantly better than low-volume bottles for detection of patients positive for microorganisms; however, the number of total microorganisms recovered were significantly better from all inoculated blood culture bottles compared to routine culture. Bedside- and laboratory-inoculated resin-containing blood culture bottles are superior to the routine method for recovery of microorganisms causing peritonitis in CAPD patients.     

Size Distributions and Light Scattering Features of Minerogenic Particles in a Stream during Runoff Events

Inorganic (minerogenic) particles received from streams during runoff events cause undesirable increases in turbidity (Tn; i.e., the light scattering coefficient, b) in many lakes and reservoirs. Quantification of particle inputs in the context of turbidity impacts and representative light scattering calculations (submodel), the necessary components in the development of a mechanistic multiple particle class model to simulate these impacts, are described for Schoharie Creek, N.Y. Light scattering attributes of minerogenic particles, including number concentration (N), size distribution (PSD), composition, and projected area per unit volume (PAVm), are quantified for three runoff events through analyses by scanning electron microscopy interfaced with automated X-ray microanalysis and image analysis (SAX). The combined credibility of the light scattering submodel and SAX to represent the light scattering features of minerogenic particles is depicted by the consistency of calculated scattering efficiencies with theory and the strength of the reported Tn-PAVm relationship. Particles in the size range of 2–10?μm were responsible for b and Tn in the stream, with greater contributions by the larger particles of this range at elevated stream flows. Empirical relationships are developed to predict N and PSD from Tn or stream flow.     

Establishing Storm-Water BMP Evaluation Metrics Based upon Ambient Water Quality Associated with Benthic Macroinvertebrate Populations

Storm-water experts agree that the currently used best management practice (BMP) percent removal methodology metric has many flaws, and some have suggested using a BMP effluent concentration metric. This case study examines establishing an effluent target concentration for BMPs that relates to the health of macroinvertebrates in the receiving water. In North Carolina, 193 ambient water quality monitoring stations were paired with benthic macroinvertebrate health ratings collected in very close proximity. Water quality for the sites ranged from excellent to poor and was divided into three distinct ecoregions: Mountain, Piedmont, and Coastal. Statistically significant relationships were found in one or more ecoregions for dissolved oxygen, fecal coliform, NH3, NO2?3?N, total Kjeldahl nitrogen, total nitrogen (TN), and total phosphorus (TP). BMPs can then be selected and designed to meet these target effluent concentrations. Based upon this research, a development, and therefore set of BMPs, in Piedmont North Carolina could be required to release TN and TP effluent concentrations of 0.99 mg/L and 0.11 mg/L, respectively. These concentrations are both associated with “good” benthos health. The new method was most effective in the Piedmont ecoregion, however with more data collection, the Mountain and Coastal ecoregions may also benefit.     

Blood cultures. Comparative study with 7 known and 2 new nutrient media for the detection of aerobic and anaerobic microorganisms (author's transl)

The growth promoting properties of seven commercially manufactured and two recently developed culture media are compared according to a standardized method. The study is carried out alternately without and with the addition of 10% fresh human blood to the culture media. The carefully selected test strains include 20 species of bacteria and 2 species of yeasts which represent obligatory aerobic, facultative anaerobic and obligatory anaerobic microorganisms with quite different nutritional and atmospherical requirements. The 9 tested media are good enough for the purpose of culturing nonfastidious bacteria. However, most of the commercially prepared media failed to detect small inocula of very fastidious microbial agents, especially when no blood is added. Collectively, thiol broth is the most noneffective medium. The last but one is thioglycollate medium. Three culture media based on brain heart infusion formula prove to be effective. Those are the commercial brain heart dextrose and the two media recently developed by the authors, namely brain heart dipeptone (BHD) and brain heart dipeptone cysteine (BHDC). BHD is the most suitable medium for the detection of obligatory aerobic and facultative anaerobic fastidious microorganisms. BHDC detects anaerobic fastidious bacteria quite effectively. The other media, namely Columbia, trypticase soy, trypticase soy sucrose, and Rosenow are of limited value with regard to the detection of small inocula of fastidious microorganisms. The causes of the unsatisfactory results with different commercial media are discussed in detail. The authors point out to the possible use of hypertonic media in special cases. Properties that should be fulfilled by blood culture media are proposed.     

Peritonitis in continuous ambulatory peritoneal dialysis. Culture of peritoneal dialysate fluid

Conventional aerobic and anaerobic culture of peritoneal dialysate effluent from patients in continuous peritoneal dialysis (CAPD) was compared to culture in a semiautomated blood culture system. During a two-year period 78 of 79 consecutive episodes of peritonitis among 45 Danish CAPD patients were cultured and the etiology of the infection found in 73 (94%). The sensitivity of the blood culture system was 88%, whereas the sensitivity of the conventional culture of the dialysate effluent was 81%. This difference is not significant (McNemar test; 0.5 > p > 0.3). The majority of isolates were Gram-positive bacteria dominated by coagulase-negative staphylococci (38%). In comparison, only 2% of the cultures of peritoneal dialysate effluent taken within the same period from patients without clinical signs of peritonitis were positive. All the Gram-positive aerobic bacteria were sensitive to vancomycin whereas 97% of the Gram-negative aerobic bacteria were sensitive to gentamicin. An initial empiric treatment of peritonitis with a combination of vancomycin and gentamicin is recommended.     

Composition and Characteristics of Excavated Materials from a New Jersey Landfill

The composition of material excavated from the Burlington County landfill in New Jersey was determined, and the major reclaimed fractions characterized. Based on a waste age map, 98 samples (80?kg each) collected from 13 gas extraction well borings were handsorted into 14 fractions and fines (<2.54?cm) that fell through the screen were collected. At least 50%, by weight, of the material was fines. The most abundant oversize materials (overs) fractions, by weight, were miscellaneous items, wood, other plastics [not polyethylene terephthalate or high density polyethylene containers], and paper. Less paper was found in the oldest (7.5–11.5?years) section of the landfill (P<0.10), most likely due to microbial degradation. Several of the characteristics of the materials excavated from the landfill, such as temperature, particle size, bulk density, volatile solids, and contamination were correlated with the age of the deposits made. High levels of adherent soil will likely prove to be an insurmountable obstacle to recycling most excavated waste fractions other than fines unless further processing is pursued.     

Variations in Wastewater Quality Parameters Influencing UV Disinfection Performance: Relative Impact of Filtration

The water-quality parameters influencing the performance of a UV disinfection system in the tailing region (typically apparent at doses greater than 30 mW?s∕cm2 in wastewater secondary effluents) are the inactivation rate coefficient (k) and the number of particles with associated coliform bacteria (Np). In this research, the natural variations of k and Np in a wastewater secondary effluent and the relative impact of filtration on reducing the variability of these two parameters was investigated. The coefficient of variation (COV) of k in the effluent of a secondary clarifier, a sand filter, and a disc filter was roughly 39% for all three effluents. The sand and disc filters reduced the COV of Np in the secondary effluent from 112% to 63% and 68%, respectively. Thus, filtration can be used to reduce the variability in Np to improve the long-term performance of a UV disinfection system. The type of filtration system necessary was found to be dependent on the average log reduction in Np required to meet the discharge requirement at the wastewater treatment plant.     

Full-scale studies of factors related to coliform regrowth in drinking water

An 18-month survey of 31 water systems in North America was conducted to determine the factors that contribute to the occurrence of coliform bacteria in drinking water. The survey included analysis of assimilable organic carbon (AOC), coliforms, disinfectant residuals, and operational parameters. Coliform bacteria were detected in 27.8% of the 2-week sampling periods and were associated with the following factors: filtration, temperature, disinfectant type and disinfectant level, AOC level, corrosion control, and operational characteristics. Four systems in the study that used unfiltered surface water accounted for 26.6% of the total number of bacterial samples collected but 64.3% (1,013 of 1,576) of the positive coliform samples. The occurrence of coliform bacteria was significantly higher when water temperatures were > 15 degrees C. For filtered systems that used free chlorine, 0.97% of 33,196 samples contained coliform bacteria, while 0.51% of 35,159 samples from chloraminated systems contained coliform bacteria. The average density of coliform bacteria was 35 times higher in free-chlorinated systems than in chloraminated water (0.60 CFU/100 ml for free-chlorinated water compared with 0.017 CFU/100 ml for chloraminated water). Systems that maintained dead-end free chlorine levels of < 0.2 mg/liter or monochloramine levels of < 0.5 mg/liter had substantially more coliform occurrences than systems that maintained higher disinfectant residuals. Free-chlorinated systems with AOC levels greater than 100 micrograms/liter had 82% more coliform-positive samples and 19 times higher coliform levels than free-chlorinated systems with average AOC levels less than 99 micrograms/liter. Systems that maintained a phosphate-based corrosion inhibitor and limited the amount of unlined cast iron pipe had fewer coliform bacteria. Several operational characteristics of the treatment process or the distribution system were also associated with increased rates of coliform occurrence. The study concludes that the occurrence of coliform bacteria within a distribution system is dependent upon a complex interaction of chemical, physical, operational, and engineering parameters. No one factor could account for all of the coliform occurrences, and one must consider all of the parameters described above in devising a solution to the regrowth problem.     

Aerobic and anaerobic microbiology of axillary hidradenitis suppurativa

A retrospective review of the microbiological and clinical data of 17 specimens obtained from axillary hidradenitis suppurativa (HS) over a period of 6 years was undertaken to study the aerobic and anaerobic microbiology of this condition. A total of 42 bacterial isolates (2.5 per specimen) were obtained, 12 aerobic or facultative (0.7 per specimen) and 30 anaerobic or micro-aerophilic (1.8 per specimen). Aerobic and facultative bacteria only were isolated in six (35%) cases, anaerobic bacteria only in seven (41%) and mixed aerobic and anaerobic bacteria in four (24%). The predominant aerobic bacteria were Staphylococcus aureus (six isolates), Streptococcus pyogenes (three) and Pseudomonas aeruginosa (two). The most frequently isolated anaerobes were Peptostreptococcus spp. (10), Prevotella spp. (seven), micro-aerophilic streptococci (four), Fusobacterium spp. (three) and Bacteroides spp. sensu stricto (three). This study highlights the polymicrobial nature and predominance of anaerobic bacteria in axillary HS and the need for antimicrobial thereby to reflect this.     

Potential Health Risks Associated with Particles in Reclaimed Wastewater

Human dose-response data from seven pathogens commonly associated with waterborne illness were used in conjunction with acceptable levels of risk specified by the United States EPA to determine an allowable particle limit for reclaimed water assuming varying degrees of pathogen association. Assuming particles contain a single pathogen, particle limits ranged from 213,000 particles/L for E. coli ETEC to 400 particles/billion L for rotavirus. Particle concentrations in the effluent from nine reclamation facilities that employed advanced filtration exceeded calculated allowable particle limits for one or more pathogens despite achieving permitted water quality standards. Hence, current methods of estimating particle densities (e.g., turbidity and suspended solids) and indicator organisms are potentially incongruent with acceptable levels of risk specified by the United States EPA. The significance of this incongruence is dependent on the uncertain frequency of pathogen association with wastewater particles.     

SBR System for Phosphorus Removal: ASM2 and Simplified Linear Model

An SBR (sequencing batch reactor) system was evaluated for nutrient removal. The system is capable of removing 95% of influent PO3?4, or from 6.7 to 0.4 mg P∕L, with the addition of acetate of 120–150 mg COD∕L in the feed solution (primary effluent). Nitrification was also achieved within the preset aeration cycle time in reducing the effluent ammonia level from 16.3–19.8 mg N∕L to 0.2–0.3 mg N∕L. However, denitrification was incomplete due to a slower endogenous nitrate respiration rate in the idle period, resulting in an effluent nitrate level of 7–8 mg N∕L. A linear version of the ASM2 (Activated Sludge Model No. 2) was developed to model the performance of an SBR system for nutrient removal. The developed model appropriately predicts the dynamic behavior of the SBR system with respect to phosphate release∕uptake, nitrification, ammonification, and denitrification. Compared with the full ASM2, the calibration of model parameters and model simulation require less computational time for practical implementation of the linear model into a process control system for the SBR.     

Aerobic and anaerobic bacteriology of cutaneous abscesses in children

Specimens from 209 cutaneous abscesses in children were cultured for aerobic and anaerobic microorganisms. Of these, nine (4%) were sterile and 51 (24%) yielded pure cultures that were predominantly Staphylococcus aureus. The rest of the abscesses yielded growth of two or more aerobic and/or anaerobic organisms. The data were organized according to these anatomic locations: head, neck, trunk, finger, nailbed, hand, leg, buttocks, perirectal, and vulvovaginal areas. Aerobic bacteria only were present in 92 specimens (46%), anaerobes only were isolated in 52 (26%), and mixed aerobic and anaerobic bacteria were present in 56 abscesses (28%). A total of 467 isolates (270 anaerobes and 197 aerobes) were recovered, accounting for 2.3 isolates per specimen (1.3 anaerobes and 1.0 aerobes). The presence of more than one anaerobe per abscess was obtained from the vulvo-vaginal, buttocks, perirectal, finger, nailbed, and head areas. Aerobes were more prevalent in the neck, hand, leg, and trunk areas. The predominant aerobes recovered were: S aureus (89 isolates), alpha- and nonhemolytic streptococci (29), group A beta-hemolytic streptococci (16), Enterobacter (10), and Escherichia coli (8). The predominant anaerobes recovered were anaerobic Gram-positive cocci (79 isolates), Bacteroides sp (116, including 31 B melaninogenicus group and 29 B fragilis group), and Fusobacterium sp (39). Our findings indicate the polymicrobial nature and predominance of anaerobes in cutaneous abscesses in children in perirectal, head, finger, and nailbed areas.