Bacteriological eutrophication indicators in four Colombian water bodies (South America)

For the first time in Colombia the relative abundance of Pseudomonas spp., Vibrio spp., Plesiomonas shigelloides , the Aeromonas hydrophila group, and the faecal and total coliforms were studied in three dams and a natural lagoon with a different trophic state. Coliforms were low in all the water bodies, but their number was greater in the dams with a greater anthropic activity. Vibrio spp. was not detected. The density of P. shigelloides was irregular. Pseudomonas spp. was always present and showed relatively high abundance. The bacteria of the A. hydrophila group were constant and their numbers increased with the trophic state, for which they could be indicators of the eutrophication phenomena. Significant correlation ( P < 0.05) was established between total and faecal coliforms and pH, transparency, nitrites, nitrates, and orthophosphates. P. shigelloides was correlated with faecal coliforms and Aeromonas hydrophila with total coliforms and transparency.     

Disinfection of sludge with high pathogenic content using silver and other compounds.

A physicochemical sludge with high microbial content (10(2)-10(4) FPU/g TS bacteriophages, 10(6)-10(7) MPN/g TS faecal coliforms, 10(4) MPN/g TS Salmonella spp., 10(4) MPN/g TS Shigella spp., 10(3) MPN/g TS Pseudomonas aeruginosa, 10(2) MPN/g TS Vibrio cholerae, 10(2)-10(3) cysts/g TS Giardia sp., 10(2)-10(4) oocyts/g TS Cryptosporidium sp., 168-215 viable helminth ova/g TS) was disinfected using silver, silver-copper, and silver-copper plus a synergistic agent (SA). Twenty milligrams Ag/g TS inactivated 4.8 log of faecal coliforms in 1 h; however, 40 mg Ag/g TS are needed to reduce helminth ova viability from 84 to 38.4% in the same period of time. Combinations of Ag-Cu (60:600 mg Ag-Cu/g TS) and Ag-SA (60:24 mg Ag-SA/g TS) inactivated 7.8 log of faecal coliforms and around 90% of helminth ova in 60 min. To produce USEPA class A biosolids, 10:100:8 and 5:50:13.3 mg Ag-Cu-SA/gTS are needed. Bacterial regrowth was not observed for all conditions producing <1000 MPN/gTS faecal coliforms, suggesting a residual disinfection effect. Recommended doses to produce class A biosolids inactivated 2-4 log of bacteriophages, 4 log of Salmonella spp., 4 log of Shigella spp., 3 log of Pseudomonas aeruginosa, 2 log of Vibrio cholerae, 87-99.9% of Giardia sp., and 75-99.9% of Cryptosporidium sp.     

The impact of cyanobacteria on growth and death of opportunistic pathogenic bacteria

Climate change may cause increased microbial growth in water sources and more knowledge is required on how this may affect the hygienic water quality, i.e., whether increased occurrence of cyanobacteria and algae may stimulate the growth rate of opportunistic pathogenic bacteria. Laboratory experiments were performed to investigate if the presence of the cyanobacteria Anabanea lemmermannii and Microcystis aeruginosa affected the survival and growth rate of the opportunistic pathogenic bacteria Aeromonas hydrophila and Pseudomonas aeruginosa, and the faecal indicators Escherichia coli and coliforms. Cyanobacteria were cultured in bottles containing the nutrient-poor medium 02. Sewage, A. hydrophila or P. aeruginosa was added to cyanobacterial cultures and the bacterial growth and survival was followed. E. coli and coliforms from sewage died within few days and the decay rate was not affected by the presence of cyanobacteria. The presence of Anabaena stimulated the growth rate of P. aeruginosa, but had no effect on the growth rate of A. hydrophila. Microcystis had no effect on the growth rate of P. aeruginosa and an inhibiting effect on the growth rate of A. hydrophila.     

Comparison of total and faecal coliforms as faecal indicator in eutrophicated surface water.

The aim of this study was to evaluate the use of total coliforms (TC) and faecal coliforms (FC) using a membrane filtration method for precise monitoring of faecal pollution in Korean surface water. The samples were collected in Korea from both main rivers and their tributaries. Presumptive TC * FC were enumerated. The ratios of presumptive FC to TC were not constant, but varied widely, and TC were difficult to enumerate because of overgrowth by background colonies. For FC this was not the case. Seven hundred and three purified strains of presumptive TC * FC and their background colonies were biotyped using API 20E. Among 272 presumptive TC, non-faecal related species, Aeromonas hydrophila dominated (34.6%) and E. coli accounted for only 5.1%. In contrast, E. coli made up 89% of the 209 presumptive FC. Furthermore, of 164 background colonies on Endo Agar LES, 54.9% was A. hydrophila, while background colonies on m-FC Agar were few (58 strains), and despite their atypical colony appearance, most of them were biotyped as enteric bacteria. These results reveal that the detection of FC rather than TC using m-FC Agar is more appropriate for faecal pollution monitoring in eutrophicated surface water located in a temperate region.     

Temporal Distribution of Faecal Pollution Indicators and Opportunistic Pathogens at a Lake Ontario Bathing Beach

In order to examine the temporal relationship between bather load and water quality indicator levels, faecal pollution indicator (faecal coliforms and faecal streptococci) and opportunistic pathogen (Candida albicans and Pseudomonas aeruginosa) levels were monitored hourly in the nearshore waters of a shallow Lake Ontario bathing beach on a hot August day when the bather load was high, and on two overcast August days when the bather load was negligible. On the high bather load day, an increase occurred in the numbers of faecal coliforms and faecal streptococci in the beach water in conjunction with an increase in the bather load; P. aeruginosa levels increased later in the day. There was little apparent relationship between C. albicans levels and the other parameters on the high bather load day. No corresponding increases were observed for any of the monitored parameters on the low bather load days. The results indicate that bather load and sample collection time may influence estimations of recreational water quality based on faecal pollution indicator and P. aeruginosa levels.     

Microbiological quality of groundwater sources used by rural communities in Limpopo Province, South Africa.

A survey of the microbiological quality of water from 194 boreholes (97 privately owned and 97 communal boreholes) in the rural Thitale-Hlanganani area of the Limpopo Province, South Africa was carried out between August 2002 and August 2003. Very little information on the microbiological quality of privately-owned boreholes in rural communities is available raising concerns about the safety of these groundwater supplies. In this study, levels of total coliforms, thermotolerant (faecal) coliforms, faecal enterococci, Clostridium perfringens (vegetative cells and spores) and somatic coliphages were determined for community and privately-owned borehole water. The average counts for total coliforms, faecal coliforms, faecal enterococci and Clostridium perfringens exceeded the South African recommended guideline limits of 0-10 counts.100 ml(-1) for total coliforms and 0 counts. 100 ml(-1) for faecal coliforms, faecal enterococci and Clostridium perfringens respectively. Comparisons between the levels of indicator bacteria present in private and communal boreholes during dry seasons indicated a statistical difference for faecal enterococci bacteria (p = 0.005) and Clostridium perfringens (p = 0.08). Comparisons between the levels of indicator bacteria present in private and communal boreholes during rainy seasons indicated statistical differences between total coliforms (p = 0.05), faecal coliforms (p = 0.03) and Clostridium perfringens (p = 0.009) bacteria. No significant differences in the presence of somatic coliphages in both private and communal borehole water were see. The results indicated the need for environmental impact assessment studies to monitor the microbiological quality of groundwater sources in rural communities.     

Disinfection kinetics of pathogens in physicochemical sludge treated with ammonia.

Ammonia is a disinfectant which can diffuse through the membrane of highly resistant structures like helminth ova. Thus, it can be considered an alternative disinfectant of wastewater sludge with high pathogenic content. In this study, the kinetic parameters of the Hom model were used to describe the inactivation with ammonia of faecal coliforms, Salmonella spp. and viable helminth ova. These were obtained in processes considering the addition of ammonia alone as well as for ammonia combined with an increase in temperature. The sludge was sampled from a municipal wastewater treatment plant using an APT (Advanced Primary Treatment) or CEP (Chemical Enhanced Primary) process. With 20% w/w of ammonia, 7 logs of faecal coliforms, 6 logs of Salmonella spp., and 83% of viable helminth ova were reduced in 2 hours contact time. To eliminate 100% of the helminth ova from samples having 88-132 ova/g TS it was needed to combine 20% of ammonia with 50 degrees C. The analysis of parameters k, n and m indicate higher resistance to inactivation of helminth ova compared to bacteria and a better performance of the ammonia process than lime stabilization to inactivate microorganisms. In addition, ammonia increased the agricultural value of the biosolids produced.     

The utility of the AC/TC ratio for watershed management: a case study.

A human-impacted watershed was monitored during the dry summer seasons in 2002 and 2003 to investigate the impact of providing access to sewer mains to local village residences. Faecal coliform concentrations were monitored at select sites along the 30-mile stretch of creek, together with faecal streptococci, enterococci and total coliforms. Analysis of the results found that levels of faecal coliforms were inadequate at identifying significant known influxes of human and animal sewage established by sanitary survey. However, the bacterial ratio of atypical colonies to total coliform colonies (AC/TC), obtained from the total coliform membrane filter assay on m-Endo media, correctly indexed human faecal impact of inadequately sewered villages located along the creek. In addition, the AC/TC ratio correctly classified the predominant source of faecal runoff in the creek headwaters as agricultural, and indicated when aged agricultural faecal material was introduced by tributaries. An approach for watershed management that uses the AC/TC ratio in addition to levels of bacteria is proposed.     

Poor-quality water in swimming pools associated with a substantial risk of otitis externa due to Pseudomonas aeruginosa.

There are many large and small public outdoor and indoor swimming pools in Tehran that hundreds of people use, especially on hot summer days. The bacteriological quality of the water of some of these pools was assayed over a period of about one year (2001-2002). To assess if these swimming pools were a health risk to users, eleven public swimming pools, in the east and northeast of the city, were examined, and the exposed people were monitored. Samples of swimming-pool waters were examined for colony counts, Escherichia coli and coliforms. In addition, Pseudomonas aeruginosa was isolated from nine (81.8%) of those pools. P. aeruginosa grew in seven (63.6%) of the swimming-pool water samples. In two (18.2%) other samples, in addition to P. aeruginosa, high rates of total bacterial count, total coliforms and faecal coliform counts were also found. At the same time, users of the swimming pools were asked to complete a questionnaire. Ear swabs were collected from 179 users with a history of ear problems during the previous two weeks. An adequate control group was chosen randomly from those who never used the investigated pools. P. aeruginosa was isolated from the ear swabs of 142 (79.3%) of the cases, as well as from 4% of the controls. Results were matched for age, sex, duration of time spent in the pools, place of occurrence and other useful information. Investigation of the contaminated swimming pools revealed that chlorination was often inadequate, especially when high numbers of people led to overuse of the pools. Although the results of this research showed that otitis externa was strongly associated with the swimming pools, due to P. aeruginosa, an extensive follow-up study is needed to determine the other possible health risks associated with public pools.     

Comparison of different trophic state indices applied to tropical reservoirs

Reservoirs represent impoundments of river flows for multiple human purposes, including hydropower generation and industrial, recreational and agricultural activities. In considering the current state of dammed rivers and future projects, there is a major concern in tropical areas regarding the water quality of these aquatic ecosystems, most being subjected to eutrophication process. To this end, the Carlson (1977), Toledo (1983), Lamparelli (2004) and Cunha (2013) trophic state indices were applied and compared in six interconnected reservoirs from the Paraíba do Sul Ecoregion in Brazil that differ in their morphometry, nutrient loadings, water retention times and altitudes. Limnological variables were measured in an extensive monitoring programme carried out from 2011 to 2014 during both the rainy and dry seasons. Application of the different numerical models resulted in different trophic state classifications. Toledo's trophic state index was considered the best for assessing the trophic state of the study reservoirs since it under‐evaluates water transparency, which can be related more to inorganic turbidity rather than to phytoplankton biomass in tropical water systems. The Carlson index, developed for temperate zone lakes, resulted in higher trophic classifications, thereby not being considered a reliable model for the study reservoirs. Both the Lamparelli and Cunha indices generally classified the study reservoirs as being in an oligotrophic state, thereby underestimating their trophic status. All the trophic state indices varied seasonally, with water transparency being the only variable significantly affected by rainfall variations. Based on the results of the present study, it was concluded that an arbitrary choice of existing trophic state indices to evaluate the water quality in tropical environments might lead to erroneous conclusions regarding the actual trophic conditions of tropical waterbodies. Further, the weak correlation observed between total phosphorus and chlorophyll‐a concentrations indicates total phosphorus might not be a key factor limiting algal growth in tropical water systems, thereby meriting more research focusing on tropical reservoirs, as well as development of new trophic state indices, including consideration of other potentially limiting factors.     

Removal of contaminants and pathogens from secondary effluents using intermittent sand filters

Intermittent infiltration percolation of wastewater through unsaturated sand bed is an extensive treatment technique aimed at eliminating organic matter, oxidizing ammonium and removing pathogens. The main purpose of this study was to determine the depuration efficiencies of a sand filter to remove contaminants from secondary wastewater effluents. Elimination of pathogenic bacteria (total and faecal coliforms, streptococci) and their relationship with the filter depth were investigated. Results showed a high capacity of infiltration percolation process to treat secondary effluents. Total elimination of suspended solids was obtained. Mean removal rate of BOD(5) and COD was more than 97 and more than 81%, respectively. Other water quality parameters such as NH(4)-N, TKN and PO(4)-P showed significant reduction except NO(3)-N which increased significantly in the filtered water. Efficiency of pathogenic bacteria removal was shown to mainly depend on the filter depth. Average reductions of 2.35 log total coliforms, 2.47 log faecal coliforms and 2.11 log faecal streptococci were obtained. The experimental study has shown the influence of the temperature on the output purification of infiltration percolation process.     

Using Ecosan sludge for crop production.

This paper presents the microbial risks associated with the reuse of Ecosan sludge in agriculture. Sludge from KwaZulu Natal Province in South Africa with a helminth ova content of 30 HO/g TS, faecal coliforms of 10(6) CFU/g TS, faecal streptococci of 10(6) CFU/g TS and Salmonella spp. of 10(5) CFU/g TS was used for this purpose. Applying different rates of sludge to spinach and carrots resulted in an increase in bacterial and helminth ova counts in crops as the quantity of sludge increased. The helminth ova content in crops was always greater in leaves than in stems, with a content varying from 2 to 15 HO/g TS for spinach with sludge application rates of 0-37.5 ton/ha and from 2-8 HO/g TS for carrot crops with sludge application rates varying from 0-35 ton/ha. Nevertheless, viability in crops was 20-25%, reducing the risk of disease. Consequently, the development of an Ecosan sludge revalorisation standard is considered important. Some recommendations are made taking into account the characteristics of the sludge as well as conditions in rural areas.     

A trophic state index for Laguna lake in the Philippines

A multivariate approach was used to develop a trophic state index. The index TSI(AVE), based on the four trophic state variables (transparency, phytoplankton, nitrate and temperature) was applied to Laguna Lake in the Philippines. The results indicated a hypereutrophic state of the lake. A Carlson‐type index was also used for the lake, but it was found that the index was not applicable to Laguna Lake.     

Microbial quality of water in Barekese reservoir and feeder streams in Ghana

Concern is growing in Ghana about the high incidence of water‐related diseases and deaths resulting from use of water contaminated with microorganisms. This water often remains unsafe for human consumption because of inadequate decontamination of microbially infected water. Data are presented in this study on the microbial quality of Barekese reservoir, which is the main drinking water reservoir for the city of Kumasi and its environs (population = 2, 5 million), and nine feeder streams in its catchment. Water samples were collected from 13 sampling sites and analysed for Escherichia coli, total and faecal coliforms. Furthermore, 18 faecal coliform isolates were randomly selected from all sampling sites and confirmed as E. coli using Analytical Profile Index 20E system. Escherichia coli, total and faecal coliforms were enumerated using the most probable number method. Mean bacterial indicator numbers from all sampling sites ranged from 1.45 × 10⁴ to 9.50 × 10⁷ 100 mL^?1 for total coliforms, 1.60 × 10³ to 9.00 × 10⁵ 100 mL^?1 for faecal coliforms and 1.50 × 10¹ to 9.50 × 10³ 100 mL^?1 for E. coli. Indicator numbers exceeded the World Health Organization (0.100 mL^?1) for E. coli and Ghana Water Resources Commission‐Target Water Quality Range of 5–100 100 mL^?1 for total coliforms and 0.100 mL^?1 for faecal coliforms in water used for domestic purposes. The identified isolates in Barekese Reservoir and its feeder streams belonged to Serratia, Enterobacter, Citrobacter, Salmonella and Klebsiella genera. Bacterial numbers were significantly (P < 0.05) higher in the feeder streams, compared with Barekese Reservoir water. This finding indicates the feeder streams pose health risks to local communities that withdraw water from them. The results of this study highlight the urgent need to raise public awareness on the adverse effects of water‐quality degradation through improper waste disposal methods in order to decrease the cost of treating the reservoir water.     

The effects of run‐of‐river dam spill on Columbia River microplankton

Dams, increasingly common in riverine systems worldwide, are particularly prevalent on the Columbia River (CR) in the United States. Hydroelectric projects, including both storage and run‐of‐river (i.e., minimal storage) structures, on the mainstem CR highly manage water flow, often by releasing water over (rather than through) dams as “spill.” To test the effects of run‐of‐river dam spill on microplankton abundance and composition, we sampled above and below two dams in the lower CR before and during spill conditions in spring 2016 and during and after spill conditions in late summer 2007. We tested the effects of location (i.e., above vs. below dams), spill condition (i.e., before, during, and after spill), and their interaction on microplankton abundance. Generally, diatoms were most abundant during springtime, whereas cyanobacteria were most abundant in late summer. Most taxa were not significantly different in abundance above and below dams, regardless of spill status; although cyanobacteria abundance was marginally higher below dams in summer 2007 (p = .04). Abundances of all taxa were significantly different between pre‐spill and spill periods in spring 2016, whereas only diatom and flagellate abundances were significantly different between spill and post‐spill periods in summer 2007. We conclude that spill conditions may influence microplankton abundance, but are not likely to affect microplankton communities on either side of run‐of‐river dams on the CR. This is important information for dam managers concerned about ecosystem impacts of spill.     

Biological risks to food crops fertilized with Ecosan sludge.

This paper presents the microbial effects of using Ecosan sludge in agriculture. Sludge from KwaZulu Natal in South Africa having a helminth ova content of around 30 HO/gTS, faecal coliforms of 10(6) CFU/gTS, faecal streptococi of 10(6) CFU/gTS and Salmonella spp. of 10(5) CFU/gTS were applied to soils to grow carrots and spinach at different rates. Results showed that helminth ova content in crops was always greater in leaves than in stems, with a content varying from 2 to 15 HO/gTS for spinach and sludge application rates of sludge of 0-37.5 ton/ha and from 2-8 HO/gTS in carrots crops for sludge application rates varying from 0 to35 ton/ha. Health risks resulting from crop consumption were calculated using the beta-poisson and the single-hit exponential models for Salmonella and helminths eggs, respectively. For Salmonella, no risks were found when consuming carrots for all the sludge rates studied while for spinach, risks were high but results were not deemed conclusive due to the technical methods used to measure bacteria. Concerning helminths, it was found that the morbidity rate will increase by 9% for the higher sludge application rates. To increase regional risks by 1% the egg content in crops needs to be less than 0.2 HO/gTS.     

Disinfection of sludge using lime stabilisation and pasteurisation in a small wastewater treatment plant.

Removal efficiency of faecal coliforms and helminth eggs was evaluated in a small wastewater treatment plant (WWTP) serving a population of 1,000. This system was formed by the association in series of a UASB reactor and four submerged aerated biofilters. The density of faecal coliforms and the count of helminth eggs were estimated in the liquid and solid phases of the system. Two different methods of disinfecting sludge were investigated: (a) chemical treatment with lime and (b) a physical treatment by pasteurisation. As expected, the association UASB + BF was very efficient at removal of helminth eggs from the final tertiary effluent, but coliforms were still present at high densities. Lime treatment and pasteurisation of sludge were very effective methods of disinfection and produced a sludge safe for final disposal.     

Changes in pollution indicators in Lake Victoria,Kenya and their implications for lake and catchment management

Monitoring of aquatic pollution is important for ascertaining the relationship between fisheries and the general ecosystem health of a lake. This study evaluated the use of changes in pollution indicators in Lake Victoria, Kenya, as a decision support tool for fisheries management and productivity. Principal component analysis (PCA; R² ≥ 0.5, P < 0.05) of physical and chemical parameters delineated sampling sites into ecological cluster zones consisting of the inner gulf (C1), mid‐gulf (C2) and open lake (C3). Test results for lead (Pb) and mercury (Hg) levels in the Nile perch tissues were found to be compliant with EU standards. The inner and mid‐gulfs of the Winam Gulf had high levels of total (1818.8 ± 102–1937.78 ± 94 cfu 100 mL^?1) and faecal (390 ± 21 cfu 100 mL^?1) coliforms attributable to urban sewage and industrial effluents exceeded WHO standards. Similarly, Winam Gulf was more polluted than the open lake, with higher total phosphorus and nitrogen concentrations, turbidity levels and electrical conductivity. Low phytoplankton biovolume and a low number of macroinvertebrates genera, and high zooplankton densities and pollution‐tolerant catfishes (e.g., Schilbe victoriae; Clarias gariepinus) were observed in Winam Gulf. Faecal coliforms and dissolved oxygen influenced the abundance of tolerant fish species (e.g., S. victoriae) in the lake. This study indicated a declining trend of ecological integrity in the Winam Gulf, compared with the open waters of Lake Victoria. An integrated management approach directed to minimizing pollution levels, especially in the Winam Gulf, is recommended to enhance fishery production.     

Effect of peracetic acid, ultraviolet radiation, nanofiltration-chlorine in the disinfection of a non conventional source of water (Tula Valley).

Water supply for human consumption requires certain quality that reduces health risks to consumers. In this sense, the process of disinfection plays an important role in the elimination of pathogenic microorganisms. Even though chlorination is the most applied process based on its effectiveness and cost, its application is being questioned considering the formation of disinfection by-products (DBPs). Therefore, alternative disinfectants are being evaluated and some treatment processes have been proposed to remove DBPs precursors (organic matter. This paper reports the results of disinfection of a non conventional source of water (aquifer recharged unintentionally with raw wastewater) with peracetic acid (PAA) and ultraviolet radiation (UV) as well as nanofiltration (NF) followed by chlorination to produce safe drinking water. The results showed that a dose of 2 mg/L PAA was needed to eliminate total and faecal coliforms. For UV light, a dose of 12.40 mWs/cm2 reduced total and faecal coliforms below the detection limit. On the other hand, chlorine demand of water before NF was 1.1-1.3 mg/L with a trihalomethane formation potential (THMFP) of 118.62 microg/L, in contrast with chlorination after NF where the demand was 0.5 mg/L and THMFP of 17.64 microg/L. The recommended scheme is nanofiltration + chlorination.     

Subsurface constructed wetlands for wastewater treatment and reuse in agriculture: five years of experiences in Sicily, Italy.

The paper reports the results of an investigation on a H-SSF constructed wetland for tertiary treatment in a small community located in eastern Sicily, Italy. The system is designed to reuse wastewater for the irrigation of olive orchards covering about 150 hectares. From March 2001 to September 2005, wastewater samples were collected and the following chemical-physical parameters were determined according to Standard Methods: temperature, pH, EC, DO, TSS (105degrees C), BOD5, COD, TN, TP. The following microbiological parameters were also evaluated: total coliforms, faecal coliforms, Escherichia coli, faecal streptococci, Salmonella, helminth eggs. Mean removal efficiencies ranged from 77 to 92% (TSS), 37 to 72% (BOD5), 51 to 79% (COD), 97 to 99.5% (E. coli). Removal efficiency of Salmonella and helminth eggs was always 100% in all samples; however, only 150% of total samples matched the limit of E. coli (< 50 CFU/100 mL) fixed by Italian legislation for wastewater reuse.