Effects Of Wastewater Discharges Research Articles

Water and sediment chemistry of a wetland treating municipal wastewater

The effects of wastewater discharge in an artificially confined wetland, Turangi land treatment facility, New Zealand, were investigated by measuring the changes in water and sediment chemistry in the land treatment facility. Analysis of surface water shows that the treatment facility is effective at removing BOD5 (85%), but not NH4‐N, SO4, PO4‐P, and total suspended solids. Surface flow measurements indicate that the effluent flows through the confined wetland in less than a day. The retention time is too short to allow exchange between wetland vegetation and effluent, thus preventing efficient contaminant removal. The change in land use c. 30 years ago associated with the construction of the land treatment facility is reflected in a change in stratigraphy and sediment chemistry. Elevated sulphur and zinc concentrations in sediments are attributed to sewage effluent discharge, and indicate that soil uptake is taking place.

Calibration of QUAL2E Model for the Sava River (Slovenia)

The use of mathematical models is a good decision making tool in river basin management for selection of wastewater treatment technologies and for estimation of the impact of discharged wastewater on the quality of receiving streams. In rivers mostly polluted with degradable organic matter, the major effect of wastewater discharge results in a substantial decrease of dissolved oxygen. The model QUAL2E developed by the United States Environmental Protection Agency was applied to wastewater impact assessment in the Sava river (Slovenia). We present the procedures for the determination of input data for the QUAL2E model. The sediment oxygen demand rate constant was determined experimentally in situ using an specially designed device; the degradation rate constant was determined in a river laboratory model; hydrological characteristics were evaluated on the basis of empirical coefficients; while the reaeration rate constant was calculated on the basis of an energy dissipation model. The mathematical water quality model QUAL2E was calibrated on the basis of field and laboratory measurements and validated with an independent set of data for critical summer low flow conditions when the dissolved oxygen concentrations are low. A sensitivity analysis of the model was also performed. The validated model was then used to estimate the impact of municipal and industrial wastewater discharges on dissolved oxygen concentrations in the Sava river near Ljubljana. The model was used to simulate various conditions in the river and various degrees of treatment of discharged wastewaters. It is estimated according to the model predictions that at critical summer low flow conditions, wastewater should be treated to reach a BOD under 30 mg l−1 with the goal that Slovenian water quality standards are not violated, meaning a dissolved oxygen concentration above 5 mg l−1.

Calibration of qual2e model for The Sava river (Slovenia)

The use of mathematical models is a good decision making tool in river basin management for selection of wastewater treatment technologies and for estimation of the impact of discharged wastewater on the quality of receiving streams. In rivers mostly polluted with degradable organic matter, the major effect of wastewater discharge results in a substantial decrease of dissolved oxygen. The model QUAL2E developed by the United States Environmental Protection Agency was applied to wastewater impact assessment in the Sava river (Slovenia). We present the procedures for the determination of input data for the QUAL2E model. The sediment oxygen demand rate constant was determined experimentally in situ using an specially designed device; the degradation rate constant was determined in a river laboratory model; hydrological characteristics were evaluated on the basis of empirical coefficients; while the reaeration rate constant was calculated on the basis of an energy dissipation model. The mathematical water quality model QUAL2E was calibrated on the basis of field and laboratory measurements and validated with an independent set of data for critical summer low flow conditions when the dissolved oxygen concentrations are low. A sensitivity analysis of the model was also performed. The validated model was then used to estimate the impact of municipal and industrial wastewater discharges on dissolved oxygen concentrations in the Sava river near Ljubljana. The model was used to simulate various conditions in the river and various degrees of treatment of discharged wastewaters. It is estimated according to the model predictions that at critical summer low flow conditions, wastewater should be treated to reach a BOD under 30 mg l −1 with the goal that Slovenian water quality standards are not violated, meaning a dissolved oxygen concentration above 5 mg l −1 .

Effects of wastewater discharge on microbial populations and enzyme activities in mangrove soils

Soil leaching experiments were conducted to assess the impact of discharging wastewater, of two salinities, on bacterial population sizes and microbial activities in mangrove soils. Synthetic wastewater, prepared in either deionized water or half-strength seawater, was applied to trays containing mangrove soils three times a week for a total of 12 weeks. Results show that the mangrove soils were capable of removing pollutants such as Cu, Zn, Cd, P and N from the wastewater. The total counts of both aerobic and anaerobic heterotrophic bacteria, nitrifiers and denitrifiers in mangrove soils receiving wastewater were significantly higher than those found in the control soils. The adenosine triphosphate (ATP) content and the activity of dehydrogenase and alkaline phosphatase in soils were also not affected by wastewater treatment. This indicates that the organic matter and nutrients present in wastewater did cause a large increase in bacterial growth in soils. The retention of heavy metals did not show any harmful effect in the first 10 weeks of this study as any inhibitory effect due to heavy metals might have been overshadowed by the stimulatory effects of the nutrients. The mangrove soils receiving wastewater prepared in deionized water (fresh water) generally had higher population sizes of various bacterial functional groups and supported more microbial activities than that treated with saline wastewater. These results suggest that the wastewater inputs (in particular, organic matter and nutrient) and salinity would have more significant effects on the microbial activities in mangrove soils than heavy metals.

Spatial and temporal patterns of the infaunal community near a major ocean outfall in Southern California

Effects of waste water discharge from a major ocean outfall in Southern California to the benthic infaunal community were examined during a 5-year monitoring programme. Natural features, primarily water depth, accounted for 82% of the variability in the infaunal community, while discharge-related effects represented less than 8% of the variability. The area immediately adjacent to the diffuser had the strongest outfall effects. Infaunal abundance showed a pattern of enhancement centred at the outfall. Diversity was also high, indicating that the area was not characterized by a degraded community.

Effect of wastewater discharge on nutrient contamination of mangrove soils and plants

Effect of wastewater discharge on nutrient contamination of mangrove soils and plants

Biological monitoring of a pulp and paper mill wastewater

The physico-chemical testing required under the E.P.A. licence enables one to gauge the chemical effects of the APM wastewater on the Latrobe River, but it tells us nothing about likely effects on the aquatic biota. The APM bio-monitoring programme was instigated to provide evidence of any effects of wastewater discharges on the rivers biota. To date the programme has shown no adverse impact downstream. The laboratory bioassays on fish and algae have recently given way to the river fauna surveys as the regular monitor of wastewater quality. It is intended to continue with regular river surveys using the river's residents as indicators of water quality and future surveys will investigate reasons for the presently obscure variation in macro-invertebrate populations.

Community metabolism of intertidal flats in the Ems-Dollard estuary

To obtain an insight into the flux of carbon through intertidal sediments of the Ems-Dollard estuary, the annual cycles of gross benthic primary production and community respiration were measured at six stations, together with a set of environmental parameters. In a stepwise multiple regression analysis it was shown that temperature alone and temperature plus viable bacteria explained 50 and 70% respectively of the observed variation in community respiration. Other variables, including the rate of primary production and amount of organic carbon in the sediment were less important. The rate of primary production could not be fitted adequately into a multiple regression equation. The annual values of community respiration (177–794 gO2·m-2·yr-1) and primary production (82–628 gO2·m-2·yr-1) were within the range of published values. except for one station in the vicinity of a wastewater outfall, which had an extreme production (average 984 gO2·m-2·yr-1). At four stations, annual community respiration exceeded primary production by 40%. It is concluded that the main carbon flux within the sediment, from CO2 to benthic primary producers, to benthic consumers and from there to CO2 again,was completed within a month or so, leaving untouched the large bulk of organic matter within the sediment. Possible effects of wastewater discharges on community metabolism are discussed.