ISSN:1061-4303    

DOI:10.2175/WER.66.1.1

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
While the dewatering of wastewater sludges has received considerable research attention, it has been assumed that the water continuum surrounding the sludge particles has the physical properties of bulk water. This paper suggests that such an assumption may not be valid. The existence of vicinal water, consisting of ordered and layered water molecules on the surfaces of submerged solids, is demonstrated using research from various disciplines. The meaning of “bound water” as used in sludge technology is discussed, and it is shown that bound water can be defined in several ways, depending on the test used. It seems reasonable that bound water as it is usually defined actually consists of three different types of water—water captured in the interstitial spaces within floes and within cells, vicinal water on the surfaces of solids, and water of hydration. Only some of the interstitial water can be removed by mechanical dewatering. Because of the large surface area of sludge particles, including living cells, it is likely that much of the bound water is vicinal water, and this cannot be removed mechanically. The determination of the various fractions of these waters may lead to a better understanding of mechanical sludge dewatering.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.2

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
Biological hydrolysis of urea was studied in an upflow anaerobic sludge blanket (UASB) reactor. Methanol was used as the source of carbon. Modified diacetyl monoxime method was used for the determination of urea in samples having a high background of ammoniacal nitrogen to hydrolyse 100% urea at loadings of 7.09 kg/m3bed vol/d and below. The reactor could be operated at 100% efficiency with NH4+‐N loading of 3.43 kg NH4+‐N/m3bed vol/d. The highest COD utilization rate was 2.32 kg/m3bed vol/d. The advantages of the UASB reactor over the fixed film‐fixed bed (FFFB) and the continuous flow stirred tank reactor (CFSTR) are discussed in the paper.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.3

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
A numerical procedure is presented which determines the volatile acid content of a sample using standard acid titration data. The procedure uses all available titration data instead of the customary single endpoint titration volume. In many cases volatile acid content can be resolved into acetic and propionic acid components. The procedure is verified using solutions of known concentrations. The procedure gives comparable results to the silicic acid chromatography separation technique.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.4

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
An anaerobic fluidized‐bed granular activated carbon (GAC) reactor employing carbon replacement was evaluated for the treatment of a simulated high‐strength industrial wastewater containing inhibitory concentrations of chlorophenols. The reactor was fed 2 000 to 5 900 mg/L acetic acid; 1 000 to 3 000 mg/L phenol; 1 200 mg/L ortho‐chlorophenol (2‐CP); 600 mg/L 2,4‐dichlorophenol (2,4‐DCP); and 150 mg/L 2,4,6‐trichlorophenol (2,4,6‐TCP). The effects of varying the carbon replacement rate, the bulk operating pH, and the organic loading on reactor performance were investigated. The system was highly effective for treating the wastewater and an overall chemical oxygen demand (COD) removal greater than 98% was achieved. Carbon replacement resulting in a GAC solids mean retention time (SMRT) of 100 days was necessary to control the buildup of an inhibitory degradation byproduct, para‐chlorophenol (4‐CP).

ISSN:1061-4303    

DOI:10.2175/WER.66.1.5

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
An economic evaluation was performed for various sludge management practices, including the biological process of metal solubilization for digested and undigested sludges, and the traditional methods of sludge management (landfill, incineration, co‐incineration, and the land spreading of liquid or dewatered sludges for agriculture).
Biological solubilization (also called bacterial leaching), including lime neutralization and land spreading, was less expensive for undigested than for digested sludge, and was competitive with land spreading of non‐decontaminated dewatered sludge for a plant treating 388 000 m3/d of wastewater. These two management practices are approximately equivalent and are less costly than all other options considered. However, for a plant treating 20 000 m3of wastewater per day, metal solubilization was 43% more costly than the frequently practiced application of dewatered sludge onto agricultural land. For both plants (388 000 and 20 000), decontamination, followed by lime stabilization and land spreading, had less of an environmental impact than any of the other management options examined.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.6

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
The effect of shock loads of long chain fatty acids (LCFA) on the activity of granular methanogenic sludge was studied with capric acid as model substrate. The results show that inhibition is primarily related to the LCFA concentration; the LCFArbiomass ratio is less important. A lethal threshold LCFA concentration can be distinguished in reactors with identical physical and chemical conditions and inoculum properties: the acetogenic and methanogenic population is killed virtually completely when the concentration exceeds 6.7 to 9.0 mol/m3capric acid. The observed variation in the threshold level may be attributable to differences in mass transfer rate from liquid to granules in different experiments. At most, 0.2% of the acetotrophic methanogens survives, when the LCFA concentration in a methanogenic digester exceeds the lethal threshold level. Mass balance analysis shows that obligate hydrogen producing acetogenic bacteria and hydrogenotrophic methanogens recover first, followed by acetotrophic methanogens. Recovery of acetotrophic methanogenesis can be described by exponential growth of a small number of survivors. Acetotrophic methanogens do not adapt to LCFA, neither after repeated exposure to toxic concentrations, nor after prolonged exposure to non‐toxic concentrations. A low LCFA (lipid) concentration in the influent promotes faster growth of acetogenic bacteria capable of degrading LCFA.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.7

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
The photocatalytic decolorization of municipal waste‐water contaminated with textile dyes was studied using a batch reactor. Degussa P25 titanium dioxide was used as the photocatalyst and proved to be effective for dye degradation when irradiated with UV light in the presence of air. In addition to removing the color from the wastewater, the photocatalytic reaction simultaneously reduced the COD which suggests that the dissolved organics had been oxidized. The activation energy for the photocatalytic decolorization reaction was only about 3 to 6 kJ/mole indicating a weak temperature dependence of the rate. These results suggest that the photocatalytic degradation of textile dyes may be a viable method for decolorizing and oxidizing organics in wastewater.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.8

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
The Madison Metropolitan Sewerage District (MMSD) has conducted a five‐year (1985‐1990) field experiment to obtain data that provide a scientific basis for regulating land disposal of sludge contaminated with polychlorinated biphenyls (PCBs). Over 1 400 samples of soil and crop tissue were analyzed. This paper presents all the field data and interpretation. The experimental design included eight different sludge treatments and controls, making it possible to study the effects of sludge concentration, sludge loading rate, and sludge application pattern on the fate of PCBs in the soil system. Each treatment was replicated three times, giving thirty test plots in all (24 sludge applications and 6 control plots). Seventy‐nine PCB congeners were detected during the study and the concentration of each PCB congener was measured in the surface soil, corn stover, and corn grain. Surface runoff runoff studies were conducted in 1988 and 1990 and congener‐specific PCB analyses were made on these as well. A first‐order disappearance model,C=C0exp(−Kt), was appropriate to evaluate the disappearance of PCBs from the surface soil layer. AT is the rate constant for PCB disappearance. Results indicate that the rate constant for disappearance of each individual PCB congener in the soil was independent of the initial PCB sludge concentration, the sludge loading rate, and sludge application pattern. Most of the 2‐, 3‐, and 4‐chlorinated PCB congeners showed significant decreases in their soil concentration with half‐lives in the range of 4 to 58 months. The more highly chlorinated PCBs were more persistent in the sludge amended farmland, but many of them did disappear. The concentration of PCBs in the runoff samples was correlated with surface soil concentration. The PCBs were associated with the runoff sediments and there was no measurable PCB in the liquid portion of the runoff. It was concluded that there is no PCB translocation into either corn grain or corn stover samples. The bioconcentration factor for PCBs in the crop tissues is zero.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.9

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT:
Laboratory‐scale fluidized bed reactors (FBRs) containing either sand or granular activated carbon (GAC) as biocarriers for immobilized bacteria were evaluated for biotreatment of chemical industry wastes. The FBRs were fed high levels of a synthetic waste stream containing aniline (ANL), methyl ethyl ketone (MEK), p‐nitrophenol (PNP) and sodium formate (FRM) at concentrations increasing from approximately 3 600 mg/L total chemical oxygen demand (COD) up to 17 000 mg/L COD. Microbial biomass attached to the GAC increased from 15 000 mg/L at a COD loading of 3.2 Kg COD m‐3d‐1to over 40 000 mg/L at a maximum COD loading of 16.0 Kg COD m‐3d‐1. The sand was colonized slower during start‐up but supported biomass levels of 2 600 to 20 000 mg/L at COD loadings up to 9.6 COD m‐3d‐3. Scanning electron microscopy confirmed biomass measurements and showed that high levels of bacteria were retained on GAC after a toxic surge in COD loading, but were significantly reduced in the sand reactor resulting in diminished performance. Specific chemical analyses showed over 99% removal of organic feed components by both reactors throughout the study. The sand reactor study was terminated early due to its inability to handle an accidental surge in COD loading. Biological solids production from the GAC reactor ranged from 0.056 to 0.184 g solids/g COD removed. The GAC reactor demonstrated a greater ability to handle rapid increases in COD loading (for adsorbable chemicals) than the sand reactor. This study has increased fundamental understanding of the operation and performance of FBRs treating a representative chemical industry waste stream and has demonstrated some advantages of GAC over sand as a biocarrier.

ISSN:1061-4303    

DOI:10.2175/WER.66.1.10

出版商:Water Environment Research Foundation (WERF)    

年代:1994

数据来源: WILEY