Evaluation of Two Techniques: mFC AND mTEC for Determining Distributions of Fecal Pollution in Small,North Carolina Tidal Creeks

Most tidal creeks in North Carolina are closed or partially closed to shellfishing. These creeks often remain closed due to the inability to determine sources of fecal pollution. This study was designed for intensive fecal coliform monitoring of Futch Creek, N.C., to try and determine sources(s) of fecal pollution. Futch Creek is a mildly polluted tidal creek, with marginal levels of fecal coliforms and could potentially be reopened. Problems in interpreting levels of fecal coliforms and pollution risks are two fold and were extremely pronounced in this study. First, several environmental factors have been shown to influence levels of fecal coliforms. Therefore, effects of temperature, salinity, tidal cycles, and rain events on fecal coliform counts were examined. There were higher fecal coliform levels in the warmer temperatures. There was a strong inverse relationship with salinity, with highest fecal coliform counts in the 10–14 g L^-1 range for both the mFC and mTEC counts with no apparent source of pollution. This trend was also observed in three other tidal creeks. Tidal cycles did affect fecal coliform counts with substantially higher counts during low tide and appeared to be more important than rain events. It is apparent that when evaluating several stations in a creek, samples must be taken during the same tidal cycle stage in order to have comparative data. Counts obtained using the mTEC method were consistently higher than mFC counts in all salinity ranges. Basic taxonomic tests were performed on fecal coliforms isolated from three salinity regimes: 0 g L^-1, 10–14 g L^-1, and 23–26 g L^-1. The mFC method in the 10–14 g L^-1 (45%) and 23–26 g L^-1 (70%) salinity range had the highest incidence of false-positive counts (non E. coli). The mTEC method also had the highest incidence of false-positive counts in the 23–26 g L^-1 (27%) and 10–14 g L^-1 (24%), none as high as the mFC method. Therefore, the mTEC method appears to be the better of the two but is still not an ideal approach.     

Performance of Phragmites Australis and Cyperus Papyrus in the treatment of municipal wastewater by vertical flow subsurface constructed wetlands

The use of constructed wetlands to treat municipal wastewater reduces energy consumption and therefore economic costs, as well as reduces environmental pollution. The purpose of this study was to compare the purification capacity of domestic wastewater using two species of plants sown in subsurface constructed wetlands with vertical flow built on a small scale that received municipal wastewater with primary treatment. The species used were Phragmites Australis and Cyperus Papyrus. For this purpose, a constant flow of 0.6 m³ day⁻¹ was fed from the primary lagoon to each of the two wetlands built on a pilot scale with continuous flow. Each unit was filled with granite gravel in the lower part and with silicic sand in the upper part of different granulometry, the porosity of the medium was 0.34, with a retention time of 1.12 days and a hydraulic load rate of 0.2 m day⁻¹. To analyze the purification capacity of wastewater, physical, chemical and biological parameters were monitored during three months. Samples were taken at the entrance and exit in each experimental unit. The results obtained in the experimental tests for the two species of plants, indicated that the Cyperus Papyrus presented a greater capacity of pollutants removal as biochemical oxygen demand (80.69%), chemical oxygen demand (69.87%), ammoniacal nitrogen (69.69%), total phosphorus (50%), total coliforms (98.08%) and fecal coliforms (95.61%). In the case of Phragmites Australis retains more solids. The species with greater efficiency in the treatment of municipal wastewater for this study was Cyperus Papyrus.     

Heavy metal and volatile organic chemical removal and treatment in on-site wastewater infiltration systems

Solvents, greases, and rinse waters from routine vehicle maintenance contain heavy metals and volatile organic chemicals (VOCs). In Wisconsin, these fluids enter catch basins along with rinsing waters and are discharged to soil infiltration systems drainfields after mixing with domestic wastewaters in a septic tank. The purpose of this study was to monitor heavy metal and VOC removal and treatment in catch basins and septic tanks at four publicly-owned motor vehicle service stations (MVSS). Cadmium, chromium, and lead were found in catch basin wastewater, septic tank effluent, and septic tank sludge at concentrations ranging from 0.002–7.7 mg L^?1. Lead was found in the highest concentration. The highest concentrations of metals were in septic tank sludge. Of the >50 VOCs scanned for in catch basin wastewater, septic tank effluent, and septic tank sludge samples, 29 were found in concentrations that exceeded analytical detection limits. Concentrations of detected VOCs ranged from 1.0–15,800 µg L^?1 and the highest concentrations of VOCs were found in catch basin wastewater and septic tank sludge. Acetone, ethylbenzene, toluene, and xylenes were the most commonly found VOCs at all sampling locations. Thus, heavy metals and VOCs were not completely removed in catch basins and were discharged to septic tanks where removal occured possibly as these contaminants settled with solids in the sludge. The level of treatment was, however, inadequate and heavy metals and VOCs were discharged to drainfields.     

A case study of mercury and methylmercury dynamics in a Hg-contaminated municipal wastewater treatment plant

A study of total Hg (Hg) and methylmercury (MeHg) was performed in a 40 mgd capacity municipal sewage treatment plant in which elemental Hg was used as a seal in 3 trickling filter center columns. Each seal contains several hundred kg of Hg. The seals have leaked repeatedly over time, prompting the current remediation study and ongoing replacement of the Hg seals with mechanical seals. A mass balance conducted three times while the seals were in place showed that the plant acted as a net source of both Hg and MeHg during normal operation. The average amount of Hg released in sludge plus effluent was 157 g Hg and 0.4g MeHg/d. Of this total, 138 g Hg and 0.3 g MeHg were in excess of influent wastewater, and were contributed by the WTP itself. About 95% of the total Hg was released in sludge, with only 6 to 7 g/d released to the receiving water body. However, on average, about 70% of the MeHg leaving the plant was released to the river. Effluent MeHg concentrations were 4–6 ng/L. The plant components that acted as the major sources of both total and MeHg within the plant were the trickling filters (TFs). Metallic Hg accidentally lost from the center column seals has accumulated in the rock filter media and underbedding of the tricking filters. MeHg production across the TFs was positively related to the Hg concentration in each of the TFs. A substantial fraction of the total Hg but not of MeHg was lost to sludge in each settling step. About 50% of the remaining MeHg appeared to be degraded during the tertiary aeration step.     

Performances of Methyl Blue and Arsenic(V) Adsorption from Aqueous Solution onto Magnetic 0.8Ni0.5Zn0.5Fe2O4/0.2SiO2 Nanocomposites

Washing-down parlours and standing areas, following milking on dairy farms, produce dairy soiled water (DSW) that contains variable concentrations of nutrients. Aerobic woodchip filters can remove organic matter, nutrients and suspended solids (SS) in DSW, but the effluent exiting the filters may have to be further treated before it is suitable for re-use for washing yard areas. The performance of a single-layer sand filter (SF) and a stratified SF, loaded at 20 L m^?2 day^?1, to polish effluent from a woodchip filter was investigated over 82 days. Average influent unfiltered chemical oxygen demand (COD_T), total nitrogen (TN), ammonium–N (NH₄–N), ortho-phosphorus (PO₄–P) and SS concentrations of 1,991?±?296, 163?±?40, 42.3?±?16.9, 27.2?±?6.9 and 84?±?30 mg L^?1 were recorded. The single-layer SF decreased the influent concentration of COD_T, TN, NH₄–N, PO₄–P and SS by 39, 36, 34, 58 and 52 %, respectively. Influent concentrations of COD_T, TN_T, NH₄–N, PO₄–P and SS were decreased by 56, 57, 41, 74 and 62 % in the stratified SF. The single-layer SF and the stratified SF were capable of reducing the influent concentration of total coliforms by 96 and 95 %, respectively. Although a limited amount of biomass accumulated in the uppermost layers of both SFs, organic and particulate matter deposition within both filters affected rates of nitrification. Both types of SFs produced final water quality in excess of the standards for re-use in the washing of milking parlours.     

Impact of Long-Term Perfluorooctanoic Acid (PFOA) Exposure on Activated Sludge Process

Poly- and perfluorinated alkyl substances (PFASs) are groups of persistent toxic substances that have been commonly detected in wastewater treatment plants (WWTPs). In some cases, the activated sludge (AS) in WWTPs will encounter special wastewaters containing PFASs up to tens of milligram per liter (mg L^?1). However, under this condition, the potential impacts of PFASs on AS process remain unclear. In the present research, a lab-scale sequencing batch reactor was continuously exposed to perfluorooctanoic acid (PFOA), used as a representation for PFASs, at 20 mg L^?1 to mimic the extreme condition. The objective is to explore the impact of PFOA on AS process in terms of its wastewater treatment performance and evolution of microbial communities. The results indicate that PFOA restrained the microbial growth and affected the dissolved organic carbon removal. These negative impacts could be recovered after long-term adaptation. Besides, 20 mg L^?1 PFOA shows limited inhibition on nitrification and denitrification, suggesting a safe exposure level of PFOA for nitrogen removal. For microbial evolution, PFOA induced changes of communities during long-term exposure. The high abundance of Bacteroidetes, Proteobacteria, and Acidobacteria maintained over time reveals their tolerance towards PFOA. The occurrences of PFOA-resistant species are also observed. The present research provides new insight into the possible impacts of typical PFAS at high concentrations on AS process.     

Fecal contamination of Finnish fresh waters in 1962–1984

We investigated fecal contamination of Finnish lakes and rivers on the basis of 132 476 observations of total coliform bacteria (TC), thermotolerant coliform bacteria (ThC) and fecal streptococci (FS) enumerated in a nationwide monitoring programme during the period 1962–1984. The number of analyses of TC was 19 672, of ThC 16 456 and of FS 96 348. The waters were classified into three groups, influenced mainly by municipal wastewaters, industrial wastewaters or diffuse loading. Annual median bacterial concentrations were used for presenting the trends. All the concentrations decreased until about 1976, except TC concentrations in the industrialized and diffuse load areas. Since 1976 the concentrations decreased more slowly or occasionally even increased, especially those of TC. In the whole data the dynamics of bacterial loads (CFU s^?1) were similar to those of annual median bacterial concentrations. The most probable explanations for the declining bacterial concentrations are increase in the human population served by wastewater treatment plants, improved sewage treatment processes, decreased wastewater volumes of the forest industry and decrease in the number of cattle. The monitoring programme continues.     

Enteric viruses in a wastewater treatment plant in Rome

Over the course of a year a series of samples were taken from a wastewater treatment plant handling domestic sewage at each stages of the process, to detect the presence of enteric viral and classical bacterial indicators, and physicochemical parameters. The viruses were isolated on BGM cell cultures and counted according to the Most Probable Number method. The values of enteric viruses varied from 10² to 10⁴/L in raw sewage and from 10⁰ to 10³ in final effluent. The efficiency of the plant at each stages during processing was evaluated. The parameters analysed show a systematic reduction of values between input and output, with average bacteriological reductions of 88% (fecal streptococci), 93% (fecal coliforms) and 94% (total coliforms), viral load reduced by 0–99%. COD and suspended solids showed a reduction of 61 % and 71% respectively. The 40% of isolated viruses were submitted to identification procedures using molecular techniques and pools of antisera. The viral types identified were enteroviruses (poliovirus and coxsackievirus B) and reoviruses. Viruses appear less easily removed than classical bacterial indicators. Reoviruses were removed less efficiently than enteroviruses.     

Treatment of Septic Effluent for Fecal Coliform and Nitrogen in Coarse-textured Soils: Use of Soil-only and Sand Filter Systems

Groundwater effluent sample collectors(zero-tension lysimeters) were installed directlybelow the drainfields of three residential onsitetreatment systems in the Clover/Chambers Creek aquiferregion of Pierce County near Tacoma, WA. The use of asplit effluent delivery system from the septic tank,where half the effluent was delivered under pressureto a normal native soil-only filter system and halfwas delivered to a sand filter system, allowed thedirect comparison of the two commonly-utilized septicsystems for treatment levels. Septic tank effluent(from the septic tank) and percolating water (between0.3 and 0.9 m beneath the effluent distributionlines) was collected between May 1991 and April 1994on 30 occasions. Samples were analyzed for fecalcoliform bacteria, nitrate, nitrite, ammonium andtotal reduced (Kjeldahl) nitrogen. Results of thisstudy indicate that the use of sand filters greatlyincreased removal of fecal coliform bacteria and totalnitrogen. Soil-only filter systems had an average of91% removal of fecal coliforms and 47%of total N; whereas sand filter systems had an averageof 99.8% removal of fecal coliforms and 80% of total N.     

Bionutrient Removal with a Sequencing Batch Reactor

Removal of nitrogen and phosphorus from a domestic wastewater using a sequencing batch reactor (SBR) was evaluated at solid retention times (SRTs) of 9.3, 13.8, and 18.3 days respectively. Oxygen uptake rates (OURs) and sludge settling characteristics were determined at each SRT investigated. COD removal, nitrification, denitrification, and phosphorus removal were accomplished by using the following operating cycle: 15-min unmixed fill; 2-hr mixed anaerobic period; 3-hr mixed aerobic period; 3-hr mixed anoxic period; 0.5-hr reaeration period; 1-hr settling period; 1-hr decant period; and a 1.5-hr idle period. Advanced wastewater treatment (AWT) standards of 5/5/3/1 mg L^-1 for biochemical oxygen demand (BOD₅), suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) could not be achieved with the bench-scale SBR.     

Hydraulic Retention Time Influence on Improving Flocculation in the Activated Sludge Processes Through Polyelectrolytes

Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L^?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.     

Impact of organic residues and mineral fertilizer application on soil–crop system: II soil attributes

The effects of crop residues alone (Cr⁺) or combined with inorganic fertilizer (FCr⁺) sewage sludge (SS) and humentos (H) on soil properties were studied in a five-season wheat–guar rotation. Incorporation of Cr⁺ and SS significantly decreased pH by 5–9%. Highest organic carbon (OC) was observed in SS plots, whereas Cr⁺ resulted in values threefold that of the control. The added effect of Cr⁺ (46%) combined with fertilizer on total nitrogen (TN) was greater than Cr⁺ by 28%. The fraction of total residue N mineralized was 71%, whereas net N mineralized in Cr⁺, SS, H and FCr⁺ plots at 0–20 and 20–40 cm depths were 39.8, 52.3, 11.4, 66.7 mg kg^?1 and 21.2, 27.9, 8.2, 41.2 mg kg^?1, respectively. Integrated application of Cr⁺ with fertilizer had a synergistic effect on P content (3.49–3.69 units), but soil levels has never exceeded 13 mg P kg ^?1. Sole Cr⁺ significantly increased topsoil cation-exchange capacity (CEC) compared with the control treatment (9.39–21.59%). Application of SS, FCr⁺ and Cr⁺ significantly increased water-holding capacity and decreased bulk density by 9–15% and 8–9%, respectively, suggesting that such practice can restore the productivity of degraded soils and improve crop yields.     

Coliform detection from river waters: Comparison between MPN and MF techniques

This paper compares three different methods used to determine fecal pollution in river water. Two of the methods are based on direct estimation using standard aerobic incubation of membrane filters (S-MF) and anaerobic incubation of membrane filters (A-MF); the third is based on statistical evaluation by the most probable number method (MPN). It was seen from regression analysis of the results obtained that the MPN, S-MF and A-MF techniques are equally valid as regards the enumeration of fecal coliforms, whereas the S-MF and A-MF techniques are more sensitive than the MPN procedure for the enumeration of total coliforms.     

Nitrogen And Phosphorus Removal In Substrate-Free Pilot Constructed Wetlands With Horizontal Surface Flow In Uganda

In constructed wetlands (CWs) with horizontal sub-surface flow, nutrient removal, especially phosphorus, is limited because the root biomass fills the pore spaces of the substrate (usually gravel), directing wastewater flow to deeper wetland media; plants are not regularly harvested; the litter formed by decomposing vegetation remains on the surface of the substrate and thus does not interact with the wastewater; and the substrate media often used provide only limited adsorption. Effective nutrient removal including rootzone oxidation, adsorption and plant uptake therefore requires sufficient interaction of wastewater with the treatment media. We assessed the feasibility of biological nutrient removal from wastewater using substrate-free CWs with horizontal flow, planted with two tropical macrophytes namely, Cyperus papyrus and Miscanthidium violaceum. The objectives were to evaluate the system treatment efficiency under semi-natural conditions, and to assess microbial and plant biomass contributions to nutrient removal in the CWs. Results showed high removal efficiencies for biochemical oxygen demand, ammonium-nitrogen (NH₄–N) and phosphorus (P) fractions in papyrus-based CWs (68.6–86.5%) compared to Miscanthidium (46.7–61.1%) and unplanted controls (31.6–54.3%). Ammonium oxidizing bacteria in CW root–mats (10⁸–10⁹ cells/gram dry weight) and residual nitrite and nitrate concentrations in the water phase indicated active system nitrification. Papyrus showed higher biomass production and nutrient uptake, contributing 28.5% and 11.2%, respectively, of the total N and P removed by the system compared to 15% N and 9.3% P removed by Miscanthidium plants. Compared to literature values, nitrification, plant uptake and the overall system treatment efficiency were high, indicating a high potential of this system for biological nutrient removal from wastewaters in the tropics.     

Sequential solar photo-fenton-biological system for the treatment of winery wastewaters

In this study, winery wastewaters are considered for degradation using heterogeneous photo-Fenton as a preliminary step before biotreatment. The heterogeneous photo-Fenton process assisted by solar light is able to partially degrade the organic matter present in winery wastewaters. When an initial hydrogen peroxide concentration of 0.1 M is used over 24 h of treatment, a degradation yield of organic matter (measured as TOC) of around 50% is reached. The later treatment (activated sludge process) allows the elimination of 90% of the initial TOC present in pretreated winery wastewaters without producing nondesired side-effects, such as the bulking phenomenon, which is usually detected when this treatment is used alone. The final effluent contains a concentration of organic matter (measured as COD) of 128 mg O2/L. The coupled system comprising the heterogeneous photo-Fenton process and biological treatment based on activated sludge in simple stage is a real alternative for the treatment of winery wastewater.     

Fecal coliform densities in a Western watershed

This paper describes the areal distribution of fecal coliform densities within the stream system of the South Platte River basin in Colorado. Low densities, e.g., 0 to 99 fecal coliforms per 100 ml, were found in mountain streams, while higher densities, e.g., 10000 to 100000 and above were found in plains streams. About 49 % of the plains stations and 3 % of the mountain stations were not in compliance with the Colorado secondary contact recreation standard of 2000 fecal coliforms per 100 ml. The higher fecal coliform densities were associated with discharges from wastewater treatment plants. This is significant from a public health standpoint since the tainted waters are spread throughout the South Platte basin to irrigated lands via streams, canals, and reservoirs. Because of current federal and state policy encouraging land treatment and reuse, such practice should be reviewed with respect to compliance with proposed fecal coliform standards, and whether such standards should be adopted.     

Operational Optimisation of Pilot Scale Biological Nutrient Removal at the Ciudad Real (Spain) Domestic Wastewater Treatment Plant

The aim of this work is optimising operating conditions for a possibleimplementation of a Biological Nutrient Removal (BNR) process in the Wastewater Treatment Plant (WWTP) of Ciudad Real (Spain). Several factors (hydraulic retention times, anaerobic nitrate concentration, sludge age and wastewater biodegradability) were tested using a pilot scale VIP (Virginia Initiative Plant) activated sludge process and domestic wastewater from the full scale plant. Hydraulic retention times used did not cause changes in N and P removal. P removal was adversely affected by anaerobic NO₃ ^- and improved with higher BOD₅/COD ratios in wastewater. Influence of sludge age was very low in P removal, but N removal was mainly affected by this factor. Final operating conditions were selected taking into account their effects over one of both nutrients. COD and SS removal were always successful. N removal was also easily reached and the main difficulty was P removal. P sludge content was very low (2.5–4%) approximately and was also affected by the same factors tested. The main factor to improve P removal was supposed to be the organic wastewater composition. Wastewater characteristics were modified by using different sources from the WWTP. Volatile fatty acids (VFA) addition to the wastewater by using supernatant of the anaerobic sludge digesters seemed to be the best practical solution for a future BNR implementation in the WWTP.     

Quality of water from some wells in saudi arabia

The quality of water from 388 wells in 6 regions in the Kingdom of Saudi Arabia has been investigated with respect to pH, total dissolved salts (TDS), nitrite, ammonium, nitrate, and faecal coliforms. Concentration of TDS varied widely, from 180 to 9350 mg L^?1, with a mean of 754 mg L^?1. Of the 388 wells, 72 (18.6%) were above the WHO limit of 1000 mg L^?1. The levels of nitrate varied significantly, ranging from 0.0 to 95.2 mg L^?1, with an average value of 20.7 mg L^?1. About 7.7% of the tested wells had nitrate content above the WHO limit of 45 mg L^?1, and 16% of the wells showed NH₄ ⁺ levels greater than 0.05 mg L^?1. Faecal coliforms were present in 21.4% of the tested well waters. The results indicated that significant nutrient and faecal coliforms contaminated of well water was occurring.     

Treatment of High Ammonium–Nitrogen Wastewater from Composting Facilities by Air Stripping and Catalytic Oxidation

Composting municipal wastewater sludge may generate composting wastewater (acid washer water and tunnel wastewater) with high ammonium–nitrogen (NH₄–N) concentration; this kind of wastewater is usually generated in a rather small daily amount. A procedure of air stripping with catalytic oxidation was developed and tested with pilot-scale and full-scale units for synthetic disposal of the high NH₄–N wastewaters from composting facilities. In air stripping, around 90% NH₄–N removal efficiency was reliably achieved with a maximum of 98%. A model to describe the stripping process efficiency was constructed, which can be used for process optimization. After catalytic oxidation, the concentrations in the outlet gas were acceptable for NH₃, NO_X, NO₂, and N₂O, but the NH₃ and N₂O concentrations limited the feasible loading range. The treatment costs were estimated in detail. The results indicate that air stripping with the catalytic oxidation process can be applied for wastewater treatment in composting facilities.