Wastewater Pond Research Articles

Preliminary assessment of geochemistry and grain-size distribution of soils in Qatar

Soil plays an important role in life, especially in the cycling and supply of nutrients and water. Soil degradation is a serious global problem. It is caused by improper use of soil for different human activities. Soil degradation can lead to a significant decline in the productivity of agricultural lands. On a global scale, the annual loss of 75 billion tons of soil (mostly through desertification and soil erosion) costs the world about US$ 400 billion. Over 33% of the global land surface is affected by desertification, while only about 11% of global soil is considered to be stable. This study aims to perform a preliminary assessment of the soil quality at different locations in Qatar. Samples were collected from 14 sites at 8 different locations in the central east of Qatar, in May 2012. These locations are representative of a variety of desert soils (Umm Al-Zubar, Sealine, Semeisma, and Umm Al-Amad), farmland (Al Sailiya), a wastewater pond (Abu-Nakhala), a sandy beach (Katara Beach) and a protected area (Biological Field at Qatar University). The samples were analyzed using a Master Sizer 2000 particle size analyzer for grain-size analysis and by using ICP-MS for geochemical analysis. The results showed significant difference in soil texture (grain-size analysis) between all the study sites. Grain-size distribution analysis showed that soils at the Abu-Nakhala wastewater pond and the Katara Beach are composed almost exclusively of coarse particles (sand-size or higher), while area 3 of the QU Biological Field contained the highest amount of fine particles (over 52% of silt and clay). Geochemical analysis of the soil samples indicate that calcium is the dominant fraction in most of the samples, with concentrations varying between 61% and 89%. Magnesium is the second most abundant element (with concentration varying between 3% and 26%), followed closely by aluminum, with concentrations between 3% and 15%. Potassium (concentrations between 1% and 8%) and iron (1% to 6%) complete the list of major elements in the studied soils.

Quantification of Bacterial Indicators and Zoonotic Pathogens in Dairy Wastewater Ponds

Zoonotic pathogens in land-applied dairy wastewaters are a potential health risk. The occurrence and abundance of 10 pathogens and 3 fecal indicators were determined by quantitative real-time PCR (qPCR) in samples from 30 dairy wastewaters from southern Idaho. Samples tested positive for Campylobacter jejuni, stx(1)- and eaeA-positive Escherichia coli, Listeria monocytogenes, Mycobacterium avium subsp. paratuberculosis, and Salmonella enterica, with mean recoveries of genomic DNA corresponding to 10(2) to 10(4) cells ml(-1) wastewater. The most predominant organisms were C. jejuni and M. avium, being detected in samples from up to 21 and 29 of 30 wastewater ponds, respectively. The qPCR detection limits for the putative pathogens in the wastewaters ranged from 16 cells ml(-1) for M. avium to 1,689 oocysts ml(-1) for Cryptosporidium. Cryptosporidium and Giardia spp., Yersinia pseudotuberculosis, and pathogenic Leptospira spp. were not detected by qPCR.

Analysis of Sino-Singapore Tianjin Eco-city��s Indicator System

Eco-city, trend of future city, aims at realizing the harmonious development among nature, technology and society. Sino-Singapore Tianjin eco-city (SSTE) is an important joint project between China and Singapore governments. To demonstrate the meaning of establishing eco-city under restrained environment is the major aim of it. SSTE has a broad range of indicators to reflect, detect, evaluate, forecast and promote its development. But whether the indicator system and its drawing up meet the development of eco-city, as well as broader part of city is uncertain. The lack of ready-made experience of the establishment of indicator system and planning management leads to inquiring the rationality and coordinate of the system. This paper tries to analyze the indicator system of SSTE, as well as difficulties in meeting indicators, reasons of difficulty arising and solutions of it, discuss effective means to establish eco-city's indicator system and make use of the function of planning. The theory of eco-city, a model of urban development, was presented in 1981 by former Soviet Union urban ecologist O.Yanitsky, which reflects the deepen cognition of the relationship between human and nature.(1) Our country is in high speed development period of urbanization, avoiding repeating errors made in the analogous period in developed countries is an essential task to us. Our country is also a country with fragile environment and scarce resources. The establishment of SSTE can make an example to the sustainable development of eco-city in restrained resources. The eco-city site is located 40 km from the center of Tianjin and 150 km from Beijing. The site is 10 km from the core district of the Tianjin Binhai New Area, with the southern tip of the site only a 10- minute drive from the Tianjin Economic-Technological Development Area. The eco-city is sited on non-arable land. Prior to development, the site of the eco-city is one-third saltpan, one-third deserted beach, and one-third water, including a 270-hectare wastewater pond. SSTE, which is a key area of our country's development, the pattern of its development demonstrates the methods of developing other parts of our country. The building of eco-city is an inevitable trend of society development. The significance of it is high lightened in the course of city development: controlling population size, upgrading the quality of population, carrying out clean production, making up public transport system, setting green parts in urban area, developing ecological agriculture, improving environment, remitting pressure in the centre of city, regulating the density of regional city and fulfilling indicators of analyzing city. The building of eco-city can make nature and city their true color. The general thinking of building SSTE is: Firstly, to build infrastructures in starting parts. Secondly, according to the master plan's quantitative and qualitative indicators, solve various problems via professional view and systematical analyses. Thirdly, build a resource-saving, environment friendly, suitable living city. SSTE puts forward the Three Harmonies and Three Can guidelines: Three Harmonies refers to harmonies between people and people, people and economical activities, people and environment. Three Can refers to can be realized, can be duplicated, and can be popularized. The major contents of eco-city is: site selection under restrained environment, indicator system based on saving energy, spatial pattern following local environment, slow pattern emphasized transport system, recycle of water resource, harmonious community and digitizing infrastructures. SSTE will be ecologically friendly, existing wetlands and biodiversity will be preserved. Green spaces will be interspersed throughout the city. Located in an area of low rainfall, SSTE will draw a

Prevalence and Intensity of Fish-Borne Zoonotic Trematodes in Cultured Freshwater Fish from Rural and Urban Areas of Northern Vietnam

Consumption of raw freshwater fish produced in both rural farm and urban wastewater ponds is a common practice in Vietnam. The present study assessed the risk of fish-borne zoonotic trematode (FZT) infection from fish raised in both these aquaculture systems in northern Vietnam. The diversity, prevalence, and infection intensity of FZT metacercariae in 1,500 freshwater fish collected from 6 sites located in rural and urban areas in northern Vietnam were investigated. The specific diagnosis of species was made by morphologic methods. The overall FZT prevalence in fish from both urban wastewater ponds and rural farm ponds was 11.2%. In wastewater ponds, the overall prevalence was 5.1%, ranging from 2.0% in tilapia to 7.3% in common and grass carp. In fish from farm ponds, the prevalence was 17.3%, and ranged from 6.7% in mud carp to 26.7% in common carp. The mean intensity of FZT infection was also higher in fish from farm ponds than that in fish from wastewater ponds (6.0% and 8.4%, respectively). The FZT species recovered from infected fish included both liver (Clonorchis sinensis) and intestinal flukes (Haplorchis taichui, Haplorchis pumilio, and Centrocestus formosanus). The prevalence of FZT in fish raised in these common farm systems represents a significant public health risk for a population with a strong cultural preference for consuming raw or inadequately prepared fish. These research results should encourage the public health and agriculture sectors to conduct the risk factor research required to develop control programs for FZT.

Parasitological risk assessment from wastewater reuse for disposal in soil in developing countries

The purpose of this work is to analyze the parasitological risks of treated wastewater reuse from a stabilization pond in the city of Piracicaba, in the State of São Paulo (Brazil), and the level of treatment required to protect public health. Samples were taken from raw and treated wastewater in stabilization ponds and submitted to a parasitological, microbiological and physicochemical analysis. The study revealed on treated wastewater the presence of Ascaris sp. and Entamoeba coli with an average density of 1 cysts L(-1) and 6 eggs L(-1), respectively. For Ascaris, the annual risks of infection due to the accidental ingestion of wastewater irrigation were 7.5 × 10(-2) in 208 days and 8.7 × 10(-2) in 240 days. For Total Coliforms and Escherichia coli in treated wastewater, the average density was 1.0 × 10(5) MPN/100 ml and 2.7 × 10(4) MPN/100 ml respectively, representing 99% and 94% removal efficiency, respectively. For BOD, COD, TS and TSS removal efficiency was 69, 80, 50 and 71%, respectively. The removal efficiency for nitrogen; ammonia nitrogen and total phosphate was 24, 19 and 68%, respectively. The average density of helminths eggs in treated wastewater is higher compared to the density of the limit value of ≤1 egg L(-1) and tolerable risk is above the level recommended by the World Health Organization. Multiple barriers are necessary for the reduction of organic matter, chemical contaminants and parasites from treated wastewater. Standards for the sanitary control of treated wastewater to be reused in agricultural irrigation areas should be compiled for developing countries in order to minimize public health risks.

Supported liquid membrane-liquid chromatography–mass spectrometry analysis of cyanobacterial toxins in fresh water systems

Harmful algal blooms (HABs) are increasingly becoming of great concern to water resources worldwide due to indiscriminate waste disposal habits resulting in water pollution and eutrophication. When cyanobacterial cells lyse (burst) they release toxins called microcystins (MCs) that are well known for their hepatotoxicity (causing liver damage) and have been found in eutrophic lakes, rivers, wastewater ponds and other water reservoirs. Prolonged exposure to low concentrated MCs are equally of health importance as they are known to be bioaccumulative and even at such low concentration do exhibit toxic effects to aquatic animals, wildlife and human liver cells. The application of common treatment processes for drinking water sourced from HABs infested reservoirs have the potential to cause algal cell lyses releasing low to higher amounts of MCs in finished water. Trace microcystins in water/tissue can be analyzed and quantified using Liquid chromatography–electrospray ionization-mass spectrometry (LC–ESI-MS) following solid-phase extraction (SPE) sample clean-up procedures. However, extracting MCs from algal samples which are rich in chlorophyll pigments and other organic matrices the SPE method suffers a number of drawbacks, including cartridge clogging, long procedural steps and use of larger volumes of extraction solvents. We applied a supported liquid membrane (SLM) based technique as an alternative sample clean-up method for LC–ESI-MS analysis of MCs from both water and algal cells. Four (4) MC variants (MC-RR, -YR, -LR and -WR) from lyophilized cells of Microcystis aeruginosa and water collected from a wastewater pond were identified) and quantified using LC–ESI-MS following a SLM extraction and liquid partitioning step, however, MC-WR was not detected from water extracts. Within 45min of SLM extraction all studied MCs were extracted and pre-concentrated in approximately 15μL of an acceptor phase at an optimal pH 2.02 of the donor phase (sample). The highest total quantifiable intracellular and extracellular MCs were 37.039±0.087μg/g DW and 5.123±0.018μg/L, respectively. The concentrations of MC-RR were the highest from all samples studied recording maximum values of 21.579±0.066μg/g DW and 3.199±0.012μg/L for intracellular and extracellular quantities, respectively.

Performance studies on constructed wetland for treatment of crocodile pond wastewater

Crocodile pond wastewater has high Biochemical Oxygen Demand (BOD5) (100 mg/L), phosphorus (6 mg/L) and nitrogen (30 mg/L). In the present study a Vertical Flow (VF) constructed wetland treatment system planted with Arundo donax was employed to achieve the wildlife discharge standards (BOD5 < 2 mg/L). Maximum Chemical Oxygen Demand (COD) removal of 68 ± 11% and 77 ± 6.2% was achieved at an organic loading rate of 80 and 120 g COD/m2/day, respectively, and the corresponding Total Kjeldahl Nitrogen (TKN) removal of around 82 ± 4.4 and 86 ± 9% was also achieved, respectively, for the same.

The King's initiatives using water hyacinth to remove heavy metals and plant nutrients from wastewater through Bueng Makkasan in Bangkok, Thailand

H.M. the King of Thailand proposed Bueng Makkasan, the repair factory belonging to the Royal Railway of Thailand (RTT), as a wastewater-collection pond of Bangkok City. It covers about 40 acres, with 5-m depth. The RRT wastewater pond functions at a repair factory and is the collection site of the direct-polluted waste of homeless people living around the pond rim and also for temporary reservoir of two influent canals. The water hyacinth aquatic plants were grown well and covered almost the entire surface area of the pond. An experimental design was laid by making a floating bamboo frame 5 m × 10 m in size and spreading systematical distribution through all parts of the pond with the coverage area 30 percent of pond surface. Data collection and analysis were conducted on plant nutrients, heavy metals and toxic chemicals in wastewater (influent, storage, and effluent) sediment, leaves and roots of water hyacinth (in fresh and compost). Also, the water hyacinth growth rate in various periods of time in relation to chemical concentration in wastewater were determined from the beginning through harvesting time. The results found that water hyacinth would be the high-absorbing plants to extract the heavy metals (such as Mn, Cd, Fe, Zn, Cu, and Pb) and plant nutrients (such as N, P, K, Ca, Mg). The floating aquatic vegetables contaminated via high concentration of heavy metals were not eaten under the regulations of Ministry of Public Health. Consequently, the compost that was made by water hyacinth showed a high concentration of heavy metals. An application of such compost would only be for flowering-plants growth, with no possibility of application to edible vegetables. The study also indicated that water hyacinth on the wastewater treatment pond would be maximized at 20 percent cover. Sunshine-open space needed the intensity of visible light for phytoplankton and other algae species to support the photosynthesis in order to produce enough oxygen for the power-digesting aerobes to degrade the organic waste in wastewaters.

TINGKAT FILTRASI RUMPUT LAUT (GRACILARIA SP) TERHADAP KANDUNGAN ORTOFOSFAT (P2O5)

The Concern of this study is to understand Gracilaria sp. function in biofiltration process as a way in removing exceeding nutrient.Laboratory analysis indicated that Gracilaria sp has the ability to reduce organic substance as orthophosphate in see water up to range 0.0082 -00.0149 ppm/days. Application of Gracilaria in waste water filtrattion is expected to be an alternative approach in shrimp pond waste water treatment.

Emissions of Ammonia, Methane, Carbon Dioxide, and Nitrous Oxide from Dairy Cattle Housing and Manure Management Systems

Concentrated animal feeding operations emit trace gases such as ammonia (NH₃), methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O). The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emission rates. The objective of this study was to determine the emission rates of NH₃, CH₄, CO₂, and N₂O from three source areas (open lots, wastewater pond, compost) on a commercial dairy located in southern Idaho. Gas concentrations and wind statistics were measured each month and used with an inverse dispersion model to calculate emission rates. Average emissions per cow per day from the open lots were 0.13 kg NH₃, 0.49 kg CH₄, 28.1 kg CO₂, and 0.01 kg N₂O. Average emissions from the wastewater pond (g m(-2) d(-1)) were 2.0 g NH₃, 103 g CH₄, 637 g CO₂, and 0.49 g N₂O. Average emissions from the compost facility (g m(-2) d(-1)) were 1.6 g NH₃, 13.5 g CH₄, 516 g CO₂, and 0.90 g N₂O. The combined emissions of NH₃, CH₄, CO₂, and N₂O from the lots, wastewater pond and compost averaged 0.15, 1.4, 30.0, and 0.02 kg cow(-1) d(-1), respectively. The open lot areas generated the greatest emissions of NH₃, CO₂, and N₂O, contributing 78, 80, and 57%, respectively, to total farm emissions. Methane emissions were greatest from the lots in the spring (74% of total), after which the wastewater pond became the largest source of emissions (55% of total) for the remainder of the year. Data from this study can be used to develop trace gas emissions factors from open-lot dairies in southern Idaho and potentially other open-lot production systems in similar climatic regions.

Dražovice reed beds and stabilisation pond wastewater treatment system: long-term operation and monitoring results

The aim of the paper is to present results of the ten years long monitoring of the treatment processes, efficiency and operation of a wastewater treatment plant combined mechanical pre-treatment, horizontal sub-surface flow reed beds and stabilisation pond as a final purification equipment. The treatment system was built in the Dražovice village (the Czech Republic, South Moravia Region) for 800 population equivalent (P.E.) in 1999. The constructed wetlands with horizontal sub-surface continual flow reed beds, as a main biological step of wastewater treatment, has been built and operated in the Czech Republic since 1990. In case of sources over 500 P.E., there is the legislative requirement for ammonia nitrogen sufficient removal in the Czech Republic. The monitored system represents a category of sources between 500 and 2000 P.E. with the higher treatment efficiency requirements. The plant has been monitored in detail since the start of operation in 1999. A detailed monitoring programme includes: wastewater flow measurement, water temperature and oxygen regime measurement, organic and nutrient pollution removal rate assessment, hydraulic characteristics of the reed bedś filtration medium. Results of the survey include treatment efficiency calculation, hydraulic and mass load assessment. The differences in the achieved efficiency are compared between vegetation and non-vegetation periods.

Phytoremediation of industrial wastewater potentiality by Typha domingensis

Phytoremediation is increasingly receiving attention as a cost effective technique that uses plants to remediate contaminants from wastewater, soil and sediments. In this study, the ability of Typha domingensis to uptake heavy metals as well as its potential application for phytoremediation was assessed. Pollutant elements concentrations were measured in samples of wastewater, sediments and Typha domingensis collected from industrial wastewater ponds, El-Sadat city, Egypt. This study specifically focused on the capacity of Typha domingensis to absorb and accumulate aluminum, iron, zinc and lead. Results indicated thatTypha domingensis was capable of accumulating the heavy metal ions preferentially from wastewater than from sediments. The accumulation of metals in plant organs attained the highest values in roots, rhizomes and old leaves. Rhizofiltration was found to be the best mechanism to explain Typha domingensis phytoremediation capability.

Persistence of two neonicotinoid insecticides in wastewater, and in aqueous solutions of surfactants and dissolved organic matter

Wastewater treatment plants receive organic contaminants, such as pesticides, which reach the sewage system from domestic, industrial or agricultural activities. In wastewater, which is a complex mixture of organic and inorganic compounds, biotic or abiotic degradation of contaminants can be affected by the presence of co-solutes. The photodecomposition in natural sunlight of two neonicotinoid insecticides, thiamethoxam and thiacloprid, was investigated in wastewater, aqueous extracts of sewage sludge and in aqueous surfactant solutions, which are abundant in wastewater. Dissipation in the dark was also studied in wastewater, due to reduction of transmitted sunlight in wastewater ponds. With regard to photolysis, thiamethoxam degraded rapidly in all the aqueous solutions. Among them sewage sludge extracts slightly modified (average half-life 17.6 h), wastewater increased (13.7 h) and non-ionic surfactants led, as a family, to the highest dissipation rates (average 6.2 h), with respect to control water (18.7 h). Additionally this pesticide also underwent a slower biodegradation process in wastewater in the dark under anaerobic conditions (around 25 d). A metabolite of thiamethoxam from the biological decomposition in wastewater was identified by HPLC/MS. On the other hand thiacloprid was found to be resistant to photo- and biodecomposition and remained almost unchanged during the experimental periods in all the tested media.

Alberta’s Oil Sands: Hard Evidence, Missing Data, New Promises

Pitched battles are a regular occurrence in northern Alberta, Canada, as development of the province’s oil sands continues to expand. One ongoing battle—with another salvo launched in February 2011 with the leak of a European Commission report1—concerns how dirty oil sands are, relative to other fuels. Another concerns the influence of the oil sands industry in monitoring its own activity.2 In an effort to cut through the rhetoric of health advocates, industry representatives, environmentalists, government officials, and local residents, the Royal Society of Canada (RSC) selected and covered expenses for an expert panel to winnow out the facts. In a report issued 15 December 20103 the panel cited substantial evidence that efforts to extract oil from the Alberta deposits have degraded air, land, and water quality to varying degrees. The extent of the degradation is sometimes controversial; water quality data, in particular, are subject to differing interpretations and attributions of causality. However, the panel says that, based on publicly available evidence, there appear to be no significant human health threats to the general population either now or from development anticipated in the next decade or so. But the panel also warns that their conclusions come with a major caveat: there are major gaps in health and environmental data, risk assessments, government oversight, information transparency, industry efforts, and disaster preparedness. The health of the region could hinge on these gaps being addressed, particularly since, according to Travis Davies, a spokesman for the Canadian Association of Petroleum Producers, 97% of projected oil extraction and processing is still to come. After the RSC panel reviewed reams of publicly available information on factors such as health status, air and water pollution, greenhouse gas emissions, land disturbance, and energy and water consumption, it concluded that “[t]he claim by some critics of the oil sands industry that it is the most environmentally destructive project on earth is not supported by the evidence. However, for Canada and Alberta, the oil sands industry involves major environmental issues on many fronts which must be addressed as a high priority.”3p293

Digestion of wastewater pond microalgae and potential inhibition by alum and ammoniacal-N

Algae are produced in considerable quantities in oxidation ponds, and may negatively affect receiving waters when discharged at high concentration. Thus in some instances they require removal prior to effluent discharge, which may be enhanced using flocculants such as alum. Harvested algal biomass could be anaerobically digested to methane for use as a renewable energy source, however, alum, has been reported to inhibit anaerobic digestion. Psychrophilic (20°C) anaerobic digestion experiments showed a 13% reduction in methane production with 200 g m(-3) alum in the flocculated algae, and a 40% reduction at an alum concentration of 1600 g m(-3). Elevated ammoniacal-N concentrations (785 g NH(4)(+)-N m(-3)) also inhibited algal digestion at 20°C when using an inoculum of anaerobic bacteria from a mesophylic municipal wastewater sludge digester. However, anaerobic digestion using a bacterial inoculum from a psychrophilic piggery anaerobic pond (in which typical ammoniacal-N levels range between 200 and 2000 g NH(4)(+)-N m(-3)) were unaffected by elevated digester ammoniacal-N levels and methane production actually increased slightly at higher ammoniacal-N concentrations. Thus, selecting an anaerobic bacterial inoculum that is already adapted to high ammoniacal-N levels and the digestion temperature, such as that form an anaerobic pond treating piggery wastewater, may avoid ammonia inhibition of algal digestion.

The Effects of Wastewater Effluent on Sexual Differentiation and Gene Expression in the American Bullfrog

The Effects of Wastewater Effluent on Sexual Differentiation and Gene Expression in the American Bullfrog

The effect of irrigation with fish pond waste water on the quality and yield of tomato under green houses

The effect of irrigation with fish pond waste water on the quality and yield of tomato under green houses

Effect of wastewater discharge on greenhouse gas fluxes from mangrove soils

Abstract The effects of wastewater on atmospheric fluxes of three greenhouse gases, nitrous oxide (N 2 O), methane (CH 4 ) and carbon dioxide (CO 2 ) from mangrove soils were investigated, and the differences among shrimp pond wastewater (SP), livestock wastewater (LS) and municipal (S) sewage were compared. The gas emissions from mangrove soils were significantly enhanced after wastewater irrigation and the highest emission of N 2 O and CO 2 were obtained from SP. High N 2 O emission was also found in S treatment, where fluxes varied from 13.42 to 16.78 μmol m −2 h −1 , but the CH 4 and CO 2 fluxes were as low as the control irrigated with tap water. Results of soil analyses indicated that the high N 2 O emissions from mangrove soils receiving SP and S treatments were attributed to the denitrification and nitrification processes, respectively. The highest CH 4 flux was recorded in LS treatment (186.14–762.40 μmol m −2 h −1 ), which also had the highest CO 2 flux. The fluxes measured during the non-irrigation period were lower than those measured 4 h after irrigation.

Nitrifying bacterial growth inhibition in the presence of algae and cyanobacteria

Nitrifying bacteria, cyanobacteria, and algae are important microorganisms in open pond wastewater treatment systems. Nitrification involving the sequential oxidation of ammonia to nitrite and nitrate, mainly due to autotrophic nitrifying bacteria, is essential to biological nitrogen removal in wastewater and global nitrogen cycling. A continuous flow autotrophic bioreactor was initially designed for nitrifying bacterial growth only. In the presence of cyanobacteria and algae, we monitored both the microbial activity by measuring specific oxygen production rate (SOPR) for microalgae and cyanobacteria and specific oxygen uptake rate (SOUR) for nitrifying bacteria. The growth of cyanobacteria and algae inhibited the maximum nitrification rate by a factor of 4 although the ammonium nitrogen fed to the reactor was almost completely removed. Terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the community structures of nitrifying bacteria remained unchanged, containing the dominant Nitrosospira, Nitrospira, and Nitrobacter species. PCR amplification coupled with cloning and sequencing analysis resulted in identifying Chlorella emersonii and an uncultured cyanobacterium as the dominant species in the autotrophic bioreactor. Notwithstanding their fast growth rate and their toxicity to nitrifiers, microalgae and cyanobacteria were more easily lost in effluent than nitrifying bacteria because of their poor settling characteristics. The microorganisms were able to grow together in the bioreactor with constant individual biomass fractions because of the uncoupled solids retention times for algae/cyanobacteria and nitrifiers. The results indicate that compared to conventional wastewater treatment systems, longer solids retention times (e.g., by a factor of 4) should be considered in phototrophic bioreactors for complete nitrification and nitrogen removal.

Seasonal Variation in the Abundance of Culex nigripalpus and Culex quinquefasciatus in Wastewater Ponds at Two Florida Dairies

Patterns of seasonal variation in the relative abundance of immature Culex mosquitoes in wastewater ponds at dairies located in 2 different regions of peninsular Florida were compared. Culex nigripalpus and Cx. quinquefasciatus were by far the most common mosquitoes collected during the study (99,344 and 106,225 individuals, respectively). Within-station differences in abundance of Cx. nigripalpus and Cx. quinquefasciatus were evident depending upon time of year. There were also between-station differences in the abundances of the 2 species depending upon time of year and station. Environmental and behavioral factors are implicated in some of the observed differences. We discuss mosquito control options for dairy ponds as well as possible impacts of mosquito production from these areas to humans and to animal health and production.