ISSN:1061-4303    

DOI:10.2175/WER.64.2.1

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

ISSN:1061-4303    

DOI:10.2175/WER.64.2.14

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

ISSN:1061-4303    

DOI:10.2175/WER.64.2.15

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

ISSN:1061-4303    

DOI:10.2175/WER.64.2.16

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
A simple nonlinear regression technique is presented for obtaining the equation of settling velocity as a function of sludge concentration based on the data obtained from multiple batch settling tests. The equation obtained is incorporated into a computer procedure for sizing a secondary sedimentation tank. The proposed procedure is used for assessing the effect of measurement error associated with the settling velocity on the design of a secondary sedimentation tank through Monte Carlo simulation. The results obtained indicate that the mean of absolute percentage error associated with the limiting solids flux capacity of a secondary sedimentation tank varies almost linearly with the level of measurement error associated with the settling velocity. It is also observed that the required clarification area can be estimated more accurately than the required thickening area. It is further noted that a better estimate of thickening area can be obtained when the desired underflow solids concentration is chosen at a lower level.

ISSN:1061-4303    

DOI:10.2175/WER.64.2.2

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Comprehensive air emission tests were conducted on two multiple‐hearth incinerators equipped with venturi scrubbers, aftercoolers, and zero‐hearth afterburners. A pilot wet electrostatic precipitator was also tested for its ability to reduce emissions from existing systems. Particulate matter, metals, organics, and acid gas emissions were measured by rigorous test procedures. Tests of existing systems indicated that the equipment was capable of reducing particulate emissions to less than 0.38 kg/Mg of dry sludge input. More than half of the particulate mass penetrating the existing equipment was less than 0.6 µm in diameter. Analysis indicated these submicron particles were enriched with volatile metals. The existing equipment demonstrated cadmium and lead control efficiencies that were significantly higher than those assumed in proposed regulations. Despite low sludge concentrations and high site‐specific control efficiencies, arsenic and cadmium emissions will exceed limits proposed in recent regulations. Dispersion factor corrections or reductions in cadmium and arsenic emissions will be needed to satisfy proposed regulations. Emission tests indicated that a wet electrostatic precipitator can greatly enhance the removal of particulate matter, metals, and total hydrocarbons that penetrated the existing systems.

ISSN:1061-4303    

DOI:10.2175/WER.64.2.3

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Odors had been a chronic operational problem at the City and County of Honolulu's Sand Island W W T P since it began service in 1979. A field survey identified the release of hydrogen sulfide as the major odor source and concluded that off‐gas collection and treatment afforded the best methods for abatement. A pilot program was initiated that tested caustic scrubbing and a chelated iron catalytic absorbent. The latter was selected based on performance, economics, and chemical‐handling requirements.
The full‐scale system was designed to treat 10.9 m3/s (23 000 scfm) of air and achieve a 95% reduction in hydrogen sulfide levels, which were expected to range from an average of 75 ppm (V/V) to a peak of 150 ppm. The design used two fiberglass packed towers operating in series followed by activated carbon adsorbers. The system has been in service since June 1986 and has shown itself to be effective in controlling odors.

ISSN:1061-4303    

DOI:10.2175/WER.64.2.4

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Biological degradation of a synthetic mixture of several phenolic compounds typically found in coal conversion wastes was investigated in the sequencing batch reactor (SBR). The mixture contained phenol;o‐,m‐, andp‐cresols; and 2,3and 3,4‐dimethylphenols and had a total chemical oxygen demand (COD) concentration of 7750 mg/L. A variety of aerobic and anoxic control strategies were tested. A strategy that included an extended anoxic period resulted in the accumulation of byproducts that adversely affected removal efficiency and overall performance. In general, however, COD removal efficiencies were greater than 99%, with effluent COD concentrations averaging between 30 and 52 mg/L.
Overdesign of the SBR (that is, hydraulic retention times in excess of that required for COD removal) resulted in the development of filamentous bacteria and poor settling characteristics in the reactor. This problem was eliminated or controlled either by introducing a short anoxic fill period or increasing the organic load.
Removal patterns indicative of diauxic growth were observed. Conventional design approaches based on overall COD removal patterns and organic load must be applied cautiously and in conjunction with the removal patterns for individual components when used to design facilities that treat multicomponent toxic wastes.

ISSN:1061-4303    

DOI:10.2175/WER.64.2.5

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Effluent monitoring data collected under the National Pollutant Discharge Elimination System (NPDES) Program were used to estimate pollutant loads from effluent discharges to the San Francisco Estuary for the period of 1984–1987. Most analyses of priority pollutant concentrations in effluents yielded “below detection limit” (BDL) results. Although many pollutants were monitored in effluents, quantitative assessment of spatial and temporal trends in loads could only be performed for four pollutants (chromium, copper, nickel, and zinc) that were detected in more than 50% of analyses. Four municipal wastewater treatment facilities accounted for approximately 50% of the total loads of these elements to the Estuary. Statistically significant declines in loads from some of the largest dischargers were observed. Modifications to procedures for collecting and reporting effluent monitoring data that would enhance the value of these data in assessments of mass loading include the use of more sensitive analytical methods for pollutants of greatest concern, increased sampling frequency for large discharges, routine reporting of B D L results in their uncensored form, and comprehensive reporting of quality assurance data.

ISSN:1061-4303    

DOI:10.2175/WER.64.2.6

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Three upflow, static‐media anaerobic reactors (USMARs), each with clean‐bed volumes of 85 L but with different heights: diameter ratios were operated at 35°C, with C O D loadings varying from 1 to 12 g/ L · d. Height‐to‐diameter ratios investigated were 1.2, 4.1, and 14.3. The reactors were fed a synthetic substrate made from nonfat dry milk and minerals.
It was hypothesized that the effect of biogas mixing on reactor performance would be greater in tall reactors than in short ones. This was found not to be the case. Based on COD removal, the tall reactor performed only slightly better than the shorter ones at loadings less than 9g/L·d. At higher COD loadings, there was no significant difference in performance. Tracer studies using lithium chloride indicated a completely mixed flow regime at COD loadings in excess of 9g/L·d. The acetogenic methanogenic activity of the VSS in all reactors varied between 0.1 and 0.2 L CH4/g VSS · d at reactor VSS concentrations higher than 1000 mg/L.

ISSN:1061-4303    

DOI:10.2175/WER.64.2.7

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY