Removal Efficiency Of Bacteria Research Articles

Combined natural organic and synthetic inorganic coagulants for surface water treatment

Research Article| June 01 2009 Combined natural organic and synthetic inorganic coagulants for surface water treatment Kebreab Ghebremichael; Kebreab Ghebremichael 1UNESCO-IHE- Institute for Water Education, Wesetvest 7, PO Box 3015, Delft 2601, DA, The Netherlands Tel + 31 15 2151772 Fax: +31 15 2122921; E-mail: k.ghebremichael@unesco-ihe.org; www.unesco-ihe.org Search for other works by this author on: This Site PubMed Google Scholar Juliet Abaliwano; Juliet Abaliwano 1UNESCO-IHE- Institute for Water Education, Wesetvest 7, PO Box 3015, Delft 2601, DA, The Netherlands Search for other works by this author on: This Site PubMed Google Scholar Gary Amy Gary Amy 1UNESCO-IHE- Institute for Water Education, Wesetvest 7, PO Box 3015, Delft 2601, DA, The Netherlands*Also at: Technical University of Delft, Stevinweg 1, 2628CN, Delft, The Netherlands Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2009) 58 (4): 267–276. https://doi.org/10.2166/aqua.2009.060 Article history Received: August 01 2008 Accepted: December 20 2008 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Kebreab Ghebremichael, Juliet Abaliwano, Gary Amy; Combined natural organic and synthetic inorganic coagulants for surface water treatment. Journal of Water Supply: Research and Technology-Aqua 1 June 2009; 58 (4): 267–276. doi: https://doi.org/10.2166/aqua.2009.060 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex The purified coagulant from Moringa oleifera obtained by simple ion exchange purification was used for the removal of turbidity, dissolved organic carbon (DOC) and bacteria from surface water. The natural coagulant was used as a primary coagulant and as a coagulant aid with metal salts. Different water quality and operational parameters such as pH, turbidity and mixing conditions were investigated. Characterization studies using fluorescence excitation emission matrix indicated that the coagulant protein from M. oleifera was a tyrosine-like protein. Turbidity and bacteria (Escherichia coli) removal efficiency of the purified M. oleifera and metal coagulants were similar. While the removal of bacteria by metal salts was mainly due to coagulation/flocculation, the removal by M. oleifera coagulant was as a result of both coagulation and growth inhibition, which is expected to improve sludge microbiological quality. Among the operational parameters, slow mixing time significantly influenced performance of natural coagulant. At optimum dosages, the crude extract increased the DOC of the treated water significantly whereas the purified coagulant showed a significant removal of fulvic-like DOC fraction. When used in combination with metal salts, adding of M. oleifera before the metal salts showed better turbidity and DOC removal than adding it after the metal salts. aluminium sulphate, bacteria, coagulation, DOC, Moringa oleifera, turbidity This content is only available as a PDF. © IWA Publishing 2009 You do not currently have access to this content.

Examining Watershed Control Bacteria Removal Efficiencies in Support of Watershed Plans

Examining Watershed Control Bacteria Removal Efficiencies in Support of Watershed Plans

Removal of Fecal Indicators and Pathogens in a Waste Stabilization Pond System Treating Municipal Wastewater in India

This study assess the removal of fecal indicators (i.e., total coliforms, fecal coliforms, E. coli, fecal streptococci, and pathogens [Salmonella sp. and helminth eggs]) in a full-scale facultative and maturation pond system with primary screening and manual grit removal facility. The capacity of the plant is 6 ML/d. The results showed that the system was able to remove approximately 2.0 to 3.5 log units of fecal indicators and almost 100% of helminth eggs. Meanwhile, Salmonella was not eliminated significantly, as only 1.26 log units removal was found. Removal efficiency of fecal indicator bacteria was reported maximum during summers (3.4 to 4.0 log units) and minimum (1.9 to 2.0 log units) in winters. Further efforts were made to seek the correlation between key physicochemical wastewater quality parameters (biochemical oxygen demand, turbidity, and suspended solids) and indicator microorganisms (total coliforms, fecal coliforms, and fecal streptococci). Among all these parameters, suspended solids showed the highest correlation coefficient (r2) with total coliforms (0.79), fecal coliforms (0.78), and fecal streptococci (0.75). These correlations manifest that the improvement of microbiological quality of wastewater is strongly linked to the removal of suspended solids.

Treatment Spent Filter Backwash Water using Dissolved Air Flotation (DAF) in Isfahan WTP

Recovering spent filter backwash water is currently receiving a great deal of attention. EPA published the Filter Backwash-Recycling Rule (FBRR) in 2001. Recycle stream may contain significant concentration of pathogens, such as, cryptosporidium and Giardia. Dissolved Air Flotation (DAF) was investigated as a possible technology alternative to simple or advanced sedimentation technology. In this study with using a pilot of DAF effluent turbidities of >20NTU could be easily obtained, when raw water turbidities were in excess of 800 NTU. Chemical requirements were low with only a single low dose of polyaluminium chloride (PACl) required binding the floc particles to form a solids matrix suitable for flotation. The results showed that the efficiency of continuous flow DAF with using PACl as coagulant for removal of Turbidity, COD, HPC, SS and MPN were 97, 72, 75, 95 and 100 percent, respectively. The statistical analyses indicated that the optimum saturation pressure is 4-5 atm, during recycle rate of 20-25 percent. The removal efficiencies of turbidity and bacteria in coagulation with sedimentation were reported up to 70 and 65 percent, while in this study using DAF with coagulant PACl could remove turbidity, COD, SS and bacterial up to 97,72, 95 and, 72 percent respectively.

Effect of different shrimp pond bottom soil treatments on the change of physical characteristics and pathogenic bacteria in pond bottom soil

Various treatments of shrimp pond bottom soil containing organic sludge were examined for the changes in pH, organic matter and removal efficiency of pathogenic bacteria ( Vibrio and Pseudomonas). The experimental period was divided into 3 phases. In the first phase, shrimp pond bottom soil and pond organic sludge were placed in the experimental tanks and subjected to 15 days of five treatments and a control. The treatments included: (1) drying in sunlight and tilling, (2) drying in sunlight and tilling with lime, (3) drying in sunlight and addition of lime, (4) drying in sunlight and addition of probiotics and (5) drying in sunlight and tilling with probiotics. The control consisted only of drying in sunlight. In the first phase, pH of all treated soil and the control decreased significantly ( P < 0.05) over the experimental period. Organic matter of the treated and control groups increased significantly ( P < 0.05) from 1.76 ± 0.05% on day 0 to 4.33 ± 0.06% on day 15. Total heterotrophic bacteria (THB) declined significantly ( P < 0.05) only in soil dried in sunlight, tilled with probiotics added (treatment 5). Vibrio species were completely eliminated within 6 days in all treatments. Pseudomonas counts decreased significantly ( P < 0.05) over time in all groups. In the second phase, water from a 3-month-old shrimp pond and pond organic sludge from the post-harvested shrimp pond were added above the treated pond bottom soils and left for 10 days in order to simulate the second crop after termination of the first phase. To begin the third phase, water was drained and the pond bottom soils subjected again to the same treatments for a further 15 days. Soil pH declined significantly ( P < 0.05) in all groups except treatment 2 over the experimental period. A significant increase ( P < 0.05) in organic matter was observed at the end of the experiment in the third phase, with values of 4.17 ± 0.13% to 4.64 ± 0.04%. THB declined significantly ( P < 0.05) in all groups over time. No Vibrio were found in any of the experimental tanks. In treatment 5, Pseudomonas was absent after day 9 of beginning the experiment in the third phase. In conclusion, drying in sunlight and tilling with probiotics were the best method for removal of Vibrio and Pseudomonas from shrimp pond bottom soil containing organic sludge.

Dissolved ozone flotation (DOF) — a promising technology in municipal wastewater treatment

In this study, dissolved ozone flotation and conventional mechanical diffuser ozonation systems have been applied to treat the downstream municipal wastewater. The process efficiency has been evaluated in the lab bench scale on the basis of the removal rate of some wastewater quality parameters, like turbidity, SS, color, UV254, COD, BOD, T-N, T-P and bacteria. DOF is found to be an efficient ozonation technique in comparison to the mechanical diffuser system under identical conditions, though the removal efficiencies of coliform bacteria are found to be the same in both cases. The optimum ozone dose of 6.1 mg/L is found in the DOF system. As for the result of this investigation, a DOF pilot plant with the capacity of 200 m 3/d was designed and set up to treat the effluence of secondary wastewater, and detailed assessment of performance was carried out during one month operation. The results indicate a good removal rate of 86.9% turbidity, 81% TSS, 72.6% color, 82.4% BOD and 92% total phosphorus. However, lower removal efficiencies of 42.9% and 33.4% were obtained for COD and T-N respectively. Almost 100% disinfection efficiency was achieved by removing heterotrophic and coliform bacteria. DOF technology is very effective and economically viable for municipal wastewater treatment in the present day context.

Assessment of a sinkhole filter for removing agricultural contaminants

The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian Region. Three USDA Natural Resource Conservation Service-designed sinkhole filters for removing contaminants from manure-impacted infiltrating water were assessed for removal efficiency of indicator bacteria and nitrate. Geometric mean fecal coliform bacteria concentrations decreased 85% to 96%. Mean nitrate concentrations increased 130% at two of the filter locations. The sinkhole filters probably filtered out sediment and associated contaminants, such as fecal coliform bacteria, but had no filtering effect on solutes like nitrate. Nitrate concentrations might have increased because of nitrification in the filter media between runoff events. The sinkhole filter appears to be an effective management tool in order to reduce inputs of pathogens to karst groundwater aquifers.

Application of culture-independent methods to assess the bacteria removal efficiency of subsurface flow constructed wetlands

The bacteriologic treatment efficiency of vertical and horizontal subsurface flow constructed wetlands (SFCWs) was analysed in two multistage wastewater treatment systems by culture dependent and independent methods. When assessed with standard cultivation procedures, bacteria removal efficiency of the vertical and horizontal SFCWs was similar. However, microscopic enumerations of the wastewater bacteria after DNA staining revealed a completely different removal pattern: bacteria removal efficiency of the horizontal SFCWs was in general low and erratic, whereas the vertical SFCWs displayed high bacteria removal rates. The discrepancies in the results obtained by bacteria enumeration and cultivation was due to a strong decrease in bacterial culturability after treatment by the horizontal SFCWs, leading to overestimation of the real bacterial concentrations in these effluents. Additionally, a PCR based approach for the detection of the enteropathogenic bacteria Campylobacter jejuni and Yersinia enterocolitica was tested in the wastewater samples. The methods were specific and reproducible in the analysed samples and could be carried out within 12 h, proving very adequate as an alternative to cultivation. This work recommends a review of the current standard methodology for wastewater quality surveillance, as well as of the design of SFCW.

Evaluation of Pathogenic Indicator Bacteria in Structural Best Management Practices

This study evaluated the bacteria removal efficiency, re-suspension and survivability within two structural Best Management Practices (BMPs) called Vortechs installed at two different sites in Providence, Rhode Island. Twelve rain storms were sampled during years 2004 and 2005. Five pathogenic indicator bacteria, E. coli, enterococci, fecal streptococci, total coliform, fecal coliform, were analyzed. Results showed that Vortechs was effective in partial removal of pathogenic indicator bacteria (PIB, 39–86%), however, the PIB concentrations after Vortechs treatment were still significantly high, which could limit the use of receiving waters and raise concerns for public health. The indicator bacteria concentrations in the sump water were 1.2-2.6 times higher than that contributed by the incoming stormwater. This result suggests some bacteria were re-suspended from the sediments within the Vortechs. Low bacterial survivability of bacteria was found in the sump water at both sampling sites; however, much lower bacteria concentrations were detected at Site 2, suggesting a higher bacteria contamination from highway runoff.

Intermittent filtration of bacteria and colloids in porous media

Intermittent filtration through porous media used for water and wastewater treatment can achieve high pathogen and colloid removal efficiencies. To predict the removal of bacteria, the effects of cyclic infiltration and draining events (transient unsaturated flow) were investigated. Using physical micromodels, we visualized the intermittent transport of bacteria and other colloids in unsaturated porous media. Column experiments provided quantitative measurements of the phenomena observed at the pore scale. Tagged Escherichia coli and a conservative tracer (NaI) were introduced in an initial pulse into a 1.5 m sand column. Subsequent hydraulic flushes without tagged bacteria or tracer were repeated every 4 hours for the next 4 days, during which outflow concentrations were monitored. Breakthrough behavior between colloids and dissolved tracer differed significantly, reflecting the differences in transport processes. Advancement of the wetting front remobilized bacteria which were held in thin water films, attached to the air‐water interface (AWI), or entrapped in stagnant pore water between gas bubbles. In contrast, the tracer was only remobilized by diffusion from immobile to mobile water. Remobilization led to successive concentration peaks of bacteria and tracer in the effluent but with significant temporal differences. Observations at the pore‐scale indicated that the colloids were essentially irreversibly attached to the solid‐water interface, which explained to some extent the high removal efficiency of microbes in the porous media. Straining, cluster filtration, cell lysis, protozoa grazing, and bacteriophage parasitism could also contribute to the removal efficiency of bacteria.

The Microorganism Community in an Aerobic Denitrification Membrane Bioreactor by 16S rDNA Based Molecular Biotechnology

In this study, the performance and microbial community in a submerged membrane bioreactor were investigated for different hydraulic retention times. The removal efficiencies of chemical oxygen demand, total phosphorus, suspended solid and heterotrophic bacteria did not differ significantly with different hydraulic retention times but the total nitrogen removal efficiency increased when the hydraulic retention time increased. Aerobic denitrification occurred during the membrane bioreactor process at hydraulic retention time of 20 hours and Thiosphera pantotropha was identified as the aerobic denitrifier by the clone-denaturing gradient gel electrophoresis method. Another denitrifying Fe+2 oxidizing bacteria was also identified at hydraulic retention time of 20 hours. In contrast, no denitrifying bacteria were identified at hydraulic retention time of 5 hours.

Particle and microorganism removal in floating plastic media coupled with microfiltration membrane for surface water treatment

Floating plastic media followed by hollow fiber microfiltration membrane was applied for surface water treatment. The performance of the system in terms of particle and microorganisms was investigated. The floating filter was examined at different filtration rates of 5, 10 and 15 m3/m2 x h. Treated water was then fed into a microfiltration unit where different filtration rates were examined at 0.6, 1.0 and 1.4 m3/m2 x d. It was found that polyaluminum chloride was the best coagulant for the removal of particle, algae and coliform bacteria. Average turbidity in treated water from the floating plastic media filter was 3.3, 12.2 and 15.5 NTU for raw water of 80 NTU and 12.9, 11.7 and 31.2 NTU for raw water of 160 NTU after 6 hours at the filtration rates of 5, 10 and 15 m3/m2 x h, respectively. The microfiltration unit could further reduce the turbidity to 0.2-0.5 NTU with low transmembrane pressure development of 0.3-3.7 kPa. Microfiltration membrane could retain most of algae and coliform bacteria remaining in the effluent from the pretreatment unit. It was found that at higher turbidity, algae and coliform bacteria removal efficiencies were achieved at lower filtration rate of the system of 5 m3/m2 x h whereas a higher filtration rate of 15 m3/m2 x h yielded better coliphage removal.

Evaluation of MBR effluent characteristics for reuse purposes

One of the advantages of MBR is its excellent effluent quality, which is suitable for a wide range of reuse purposes. We investigated the characteristics of MBR effluent and evaluated them based on the Japanese guideline for the reuse of treated wastewater. As the result, MBR effluent showed qualitative coaracteristics that satisfy the requirement except chromaticity for recreational purpose. Further treatment, such as by oxone or activated carbon, will be required to remove the remaining color. MBR shows high removal efficiency of bacteria and other hazardous microorganisms such as Cryptosporidium. We investigated the removal efficiency of virus by MBR using coliphage as an alternative index. The results showed that high removal efficiency for coliphage could be obtained by MBR. The removal mechanism appears to be that coliphage are attached to the activated sludge and thus rejected by the membrane together with activated sludge particles. With regard to the endocrine disrupters, no significant differences were observed between MBR and CAS in the removal of main endocrine disrupters.

Treatment of agricultural wastewater in two experimental combined constructed wetland systems in a tropical climate

Two designs of experimental combined constructed wetland systems were constructed: vegetated (Scirpus grossus Linn) subsurface horizontal flow bed followed by a vegetated vertical flow bed and a vegetated vertical flow bed over an unvegetated horizontal flow sand bed. The systems were used to compare the nitrification/denitrification efficiency in a tropical climate which has temperatures above an average of 25 degrees C throughout the year. The effluent from a biogas digester of pig farm wastewater with TKN and COD concentrations of approximately 400 and 1,000 mg/L was fed every 4 hours intermittently. The effluent was recycled to the system with the ratio of 1:1 and the hydraulic loading rate was increased from 3 to 6 and 12 cm/d including recycled water. At higher hydraulic loading rates, nitrogen COD and BOD removal efficiencies were lower. The SS, TP and fecal coliform bacteria removal efficiencies were not clearly affected by the high hydraulic loading or the different layout of the system. Nitrogen uptake by plants was very low in relation to the nitrogen loading of the systems. In general, the removal efficiencies of both types were comparable but the system with a vertical flow over horizontal flow sand bed is more suitable for sites with limited land area, although its construction can be more difficult than the system with horizontal flow followed by a vertical flow bed.

Vegetation effects on fecal bacteria, BOD, and suspended solid removal in constructed wetlands treating domestic wastewater

Constructed wetlands have emerged as a viable alternative for secondary treatment of domestic wastewater in areas with landscape limitations, poor soil conditions, and high water tables, which limit installation of full-scale adsorption fields. Existing information on the effects of macrophytes on treatment performance is contradictory and mostly derived from greenhouse mesocosm experiments. This study investigated the removal efficiency of fecal bacteria, biological oxygen demand (BOD), and total suspended solids (TSS) in 12 constructed wetlands treating secondary effluent from single household domestic wastewater in Kentucky. The wetlands were monoculture systems planted to cattails ( Typha latifolia L.) or fescue ( Festuca arundinacea Schreb.), polyculture systems planted with a variety of flowering plants, and unplanted systems. Influent and effluent samples were taken on a monthly basis over a period of 1 year and analyzed for fecal coliforms (FC), fecal streptococci (FS), BOD and TSS. The findings suggested no significant differences ( P<0.05) in the average yearly removal of fecal bacteria (>93%) between systems, with the vegetated systems performing best during warmer months and the unplanted systems performing best during the winter. The vegetated systems showed significantly greater ( P<0.05) removal efficiencies for BOD (>75%) and TSS (>88%) than the unplanted systems (63 and 46%, respectively) throughout the year. Overall, the polyculture systems seemed to provide the best and most consistent treatment for all wastewater parameters, while being least susceptible to seasonal variations. The performance of the cattail systems may improve by harvesting the plants at the end of the growing season, thus reducing additional BOD and TSS inputs from decaying biomass litter. The fescue systems were generally inferior to the polyculture and cattail systems because of their shallow rooting zone and limited biofilm surface area, while the unplanted systems were completely inefficient for BOD and TSS removal and should not be recommended.

Dynamics of pollution-indicator and pathogenic bacteria in high-rate oxidation wastewater treatment ponds

The spatio-temporal dynamics and removal efficiency of pollution-indicator (total coliforms, fecal coliforms and fecal streptococci) and some opportunistic pathogenic bacteria ( Pseudomonas aeruginosa and Aeromonas spp.) were studied in two high-rate oxidation ponds (HROP) A and B pilot-plants. The more evident component of the pollution-indicator bacteria dynamics in HROP effluents was an annual periodicity, based on higher concentrations in winter than in summer. The temporal dynamics of opportunistic pathogenic bacteria studied in HROP effluents was more complex than that of fecal-indicator bacteria. While a 6- or 4-month periodicity appeared, respectively, in the effluents of HROP A and B for Aeromonas spp. abundance, no particular trends were highlighted by chronological analyses for Pseudomonas aeruginosa. Removal efficiency of fecal-indicator bacteria by HROP reached a maximum in summertime and a minimum in wintertime. On the other hand, for each season, removal efficiency was always higher when the retention time is the longest. The relatively low removal of Pseudomonas aeruginosa and Aeromonas spp. showed that HROP efficiency should be improved. When HROP sanitary performance was compared to that of conventional wastewater treatment lagoons (CTL) located in the same area, it appears that HROP is the most efficient treatment system. On the other hand, HROP operates with specific load of 500 kg COD/ha/day (vs 100 kg COD/ha/day for CTL). Thus, the required surface area is five times smaller for HROP than for CTL.

Improved procedure for wastewater biofilm removal and analysis

Fixed-film processes for wastewater treatment are becoming widely used. Their efficiency is usually estimated only from substrate removal rate measurements. A better understanding of fixed culture composition and activity is needed to optimize processes in which they are involved. These analyses often require that biofilms are removed from their substrata, but this procedure is one of the most limiting steps in biofilm investigations, especially when cell counts are involved. The main objective of the study was to develop an optimal removal procedure based on sonication for analysis of biofilm parameters such as total and active bacterial counts by epifluorescent microscopy (4',6-diamidino-2-phenylindole (DAPI) and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) stainings) and total organic content as estimated by total proteins determination and chemical oxygen demand measurements. Experiments were carried out on nitrifying biofilms developed on a plastic granular substratum. Results confirmed that the removal step is crucial in biofilm analysis. The repeatability of bacterial enumeration was evaluated as well as the efficiency of sonication treatment and optimal conditions for attached cell removal. Within the studied range of sonication conditions, the sonication time and the duty cycle improved the removal efficiency of active bacteria, whereas the sonication power had the opposite effect.

Slow Sand Filtration: Influences of Selected Process Variables

Biological activity within the sand bed had the strongest influence on removal efficiency of total coliform bacteria by slow sand filtration, as determined by six pilot filters (shown above). Temperature, sand bed depth, and sand size also had strong influence.