ISSN:1061-4303    

DOI:10.1002/j.1554-7531.1996.tb00162.x

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

This paper evaluates the feasibility of using shredded tires for removal of organic compounds from landfill leachate. From the batch sorption isotherm experiments, tire chips were found to have 1.4% to 5.6% of the sorption capacity of granular activated carbon on a volume basis. The sorption equilibrium occurred within 2 days for 0.6‐, 1.3‐, and 2.5‐cm size tire chips. The capacity of tire chips to adsorb organic compounds in a multisolute system was almost equal to that in single‐solute systems. Only 3.4% to 7.9% of the organic compounds sorbed in tire chips were desorbed. A design method was proposed to estimate the thickness of a tire layer required for a target organic compound removal from the landfill leachate based on a structure‐activity relationship obtained from laboratory tests.

ISSN:1061-4303    

DOI:10.2175/106143096X127154

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

Two field sites with soil limitations (shallow depth to restrictive layers) were used in the evaluation of slow rate spray irrigation as an alternative methodology to conventional on‐site wastewater treatment are disposal. Secondary treatment and disinfection of the effluent was performed before application to the soil‐plant system at rates of 1.25 and 2.5 cm/wk. After 20 months of effluent application at Site 1 and 12 months of application at Site 2, adequate wastewater renovation was occurring at both sites. Nitrogen removal rates by the soil‐plant system were between 85% and 95%, with NO3−‐N concentrations in shallow groundwaters at both field sites less than 0.8 mg/L. Phosphorus removal rates were at least 96%. Storm water runoff quality measurements from Site 1 indicated no serious threat to nearby surface waters. Small increases in soil NO3−‐N and NH4+‐N concentrations to the 30‐cm depth occurred only at Site 2. There was no evidence of increased soil PO4‐P concentrations as a result of wastewater irrigation. The soil moisture content increased slightly at depths measured from 30 to 150 cm during summer months at both sites. Both sites demonstrated that the renovation capacity of on‐site spray irrigation systems in soils with limitations can be very efficient.

ISSN:1061-4303    

DOI:10.2175/106143096X127163

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

Two nitrification‐denitrification systems were used to determine the possible inhibitory and/or toxic effects of supplemental chromium and nickel addition to the nitrification‐denitrification process in the treatment of a relatively high ammonia, low biodegradable carbon, municipal landfill leachate. Results indicated that chromium (Cr+3) and nickel (Ni+2) caused inhibitory effects to the system at soluble concentrations of approximately 0.30 and 0.70 mg/L, respectively. Chromium affected both the nitrification and denitrification process, whereas nickel impaired only the nitrification performance; denitrification was unaffected at the nickel concentrations used. The failures were believed to be due to either the soluble metal levels themselves or the buildup of metals in the solids, although lack of long‐term acclimation cannot be ruled out. No phosphorus deficiency was noted in either case. This ruled out the possibility of system failures due to lack of bioavailable phosphorus, as reported with zinc in the early stages of this study.

ISSN:1061-4303    

DOI:10.2175/106143096X127172

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

Since the passage of the Clean Water Act in 1972, significant construction and upgrading of water pollution control plants has occurred throughout the Hudson‐Raritan Estuary. This has reduced the discharge of untreated wastewater into the estuary from approximately 19.7 m3/s (450 mgd) in 1970 to less than 0.2 m3/s (5 mgd) by 1988. The impact of this on water quality in the region was assessed by examining trends in a long‐term ambient total coliform monitoring data set. Total coliform bacteria have been monitored each summer from 1968 to 1993, as indicators of wastewater‐related pollution at 40 sites throughout the lower Hudson‐Raritan Estuary. Coliforms exhibit significant long‐term improvements throughout the estuary (that is, order‐of‐magnitude reductions over the past 26 years). Declines in coliform concentrations from 1968 through 1988 are primarily in response to plant construction and upgrades. Continued declines from 1989 through 1993 are attributed to several other New York City water pollution control programs. These programs have resulted in the abatement of 0.045 5 m3/s (1.04 mgd) of illegal discharges; reduced raw wastewater bypassing by 0.15 m3/s (3.4 mgd) due to increased surveillance and inspection of sewers; and increased capture of wet weather combined sewer overflows. In 1993, estimated compliance with New York State total coliform and fecal coliform standards was the highest ever recorded by this program. These improvements have resulted in the reopening of beaches and the lifting of wet weather bathing advisories.

ISSN:1061-4303    

DOI:10.2175/106143096X127181

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

The oxygen uptake process in a respirometer was analyzed by a mathematical model consisting of oxygen transfer accompanied with oxygen consumption reaction. The criterion to avoid an oxygen‐transfer limitation was derived on the basis of the ratio of the maximum biochemical reaction rate to the maximum possible oxygen‐transfer rate. The maximum biochemical reaction is described by the first‐order rate equation, whereas the maximum possible oxygen‐transfer rate is calculated by multiplying the oxygen‐transfer coefficient with the solubility of oxygen in water. An oxygen‐transfer coefficient in a respirometric reactor was estimated as 1.8 h−1, by using the model analysis of an oxygen uptake data from the same reactor. A simplified criterion for a respirometer without oxygen‐transfer limitation is then obtained asXS≪ 16.51/K1whereXandSrepresent concentration of biomass and substrate, respectively, and K1is the first‐order rate constant, (L/mg VSS)/h.

ISSN:1061-4303    

DOI:10.2175/106143096X127190

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

Because the bioavailability of a trace metal, and consequently its toxicity, is dependent on the physical and chemical form of the metal, we have presented a detailed assessment of how speciation of copper would be expected to affect its toxicity. Principles of chemical speciation are applied to demonstrate that inorganic forms will be in constant proportion to each other and to free copper ion during the course of the titration of a sample of natural water with copper or in the various treatments in a toxicity test conducted at constant pH and alkalinity. Binding of copper to dissolved organic matter or to suspended particulate matter may render the copper nonbioavailable. We have considered a simple complexation model to describe the complexation of copper to soluble ligands. Naturally occurring dissolved organic matter is present at concentrations only slightly greater than that of copper. Consequently, titration of water with copper results in a nonlinear relationship between the concentration of copper present as free copper ion plus inorganic copper species. The effects of stability constant of the complex, concentration of ligand, and the total copper concentration are evaluated. We have related bioavailable copper to the concentration of free copper ion plus inorganic copper complexes, which is valid if the pH and alkalinity of the waters used to develop a criteria are not different. On the basis of limited field data for the complexation of copper in Narragansett Bay water, we do not expect that significant differences in water quality criteria (WQC) would result if the criteria were to be based on free copper ion plus inorganic copper complexes rather than total copper concentrations. We examined the effect of speciation of copper in different waters as related to empirical or theoretically calculated water effect ratios (WER). We show that, on the basis of sound chemical principles, it would be expected that the most sensitive organisms would have the greatest WER. This prediction is confirmed by the empirical observations available. For insensitive organisms, knowledge of the concentration of ligand is sufficient to reasonably predict the WER. However, for the more sensitive organisms that give higher WERs, it is necessary to measure or calculate the speciation of copper to predict the WER. Use of predicted WERs may replace use of empirically derived WERs as is now part of regulatory guidance for derivation of site‐specific WQC. if correspondence has been demonstrated.

ISSN:1061-4303    

DOI:10.2175/106143096X127307

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

The parameters determining the annual balances of nitrogen (N) and the concentrations of total N in lakes were analyzed. This was carried out by the use of multiple regression analyses on data from a number of northern temperate lakes with a hydraulic detention time of 0.25 yr or more. The result indicated that the removal of N in a lake, which in most cases is dominated by denitrification, seems to be controlled by organic matter. If no major N fixation is taking place, the concentration of total N in the epilimnion during summer is proportional to the load of N and inversely proportional to the concentration of total P or chlorophylla. For some lakes N fixation is taking place. The increase in total N due to N fixation was found to be proportional to the concentration of total P reduced by a fraction of the estimated N concentration without any fixation. For most lakes, the effect of N fixation is to balance the N content with the P content, which means that the algal biomass is limited by the P content. A ratio of the total concentrations N/P less than approximately 10 indicates a rate of denitrification exceeding the capacity of N fixation. N is not balanced with P, and the algae is controlled by N.

ISSN:1061-4303    

DOI:10.2175/106143096X127208

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

Air stripping is a common way to remove volatile organic compounds (VOCs) from drinking water with the off‐gas from air stripping often requiring treatment. The removal of the VOCs from the off‐gas can be achieved by adsorbing the VOCs onto granulated activated carbon (GAC). When the capacity for GAC to adsorb VOCs becomes exhausted, VOCs are again released to the atmosphere. A previous model of the GAC adsorption process used molar volume,VM, as an affinity coefficient to predict the breakthrough curves of the VOCs; however, an additional correction factor,δ, which had no theoretical base was necessary to adequately fit multicomponent breakthrough curves.
In this paper, Hilderbrand's cohesive energy density term,c, is applied as the correction factor providing a more theoretical basis for multicomponent adsorption. Whencis applied to theVMaffinity coefficient, the heat of vaporization (Hv) adequately describes the multicomponent data and does not require additional correction factors to fit the breakthrough curves of a mixture of seven different chlorinated VOCs.

ISSN:1061-4303    

DOI:10.2175/106143096X127217

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY

摘要:

An on‐line integrated control system was devised for an activated sludge process. The process treats wastewater from a food processing plant where the disposal rate and composition of wastewater fluctuate drastically. The major objectives of the control system were to maintain the process effluent chemical oxygen demand (COD) below 50% of the regional regulation limit and to minimize the cost of aeration.
The integrated control system consists of two layers, supervisory control and process control layers. In the process control layer, six independent control loops were configured for four kinds of process variables; influent flow rate, pH, DO, and mixed liquor suspended solids of the series of aeration tanks. In the supervisory control layer, a rule‐based expert system was used to provide optimum set points for the process control layer. In addition, a valve position control loop was designed to minimize the throttling loss through aeration valves and a rule‐based load distribution system was devised to prevent some of the blowers from being excessively worn out.
The developed control system has been successfully operated for over 2 yr. After installation of the integrated control system, the average effluent COD was decreased by more than 50% compared with the COD before installation, and at the same time the cost of aeration was reduced by about 50%.

ISSN:1061-4303    

DOI:10.2175/106143096X127226

出版商:Water Environment Federation    

年代:1996

数据来源: WILEY