Fecal Coliform Removal Research Articles

Application of Ceramic Filter for Improvement of Pond Sand Filter’s Water Quality

Paying attention to the use of surface water a household type filter unit adding with existing Pond Sand Filter (PSF) is introduced as an alternative water supply option where groundwater is contaminated with arsenic/iron or excessive saline and freshwater aquifers are not available. The performances of existing PSFs are not satisfactory due to poor operation and maintenance, shorter filter run and poor treated water quality. In this study a simple and low cost ceramic filter unit consists of clay pot (10L-capacity), ceramic filter core, storage tank and wooden stand, were applied. The combined action of PSF with ceramic filter unit, the average total coliform and fecal coliform removal efficiencies were found to be 99.73% and 99.97% respectively. Moreover, the reduction efficiencies of turbidity, and color were also achieved to be 96.89% and 99.90% respectively. The average discharge rate of the filter was observed to be 3.0 lit/hr. In combination with PSF, this kind of ceramic filter would be a reliable and sustainable treatment option particularly appropriate for problematic area in Bangladesh.

Fly ash-amended pervious concrete pavement followed by bamboo bioretention basin with Dracaena sanderiana for urban stormwater runoff control

This study assessed the feasibility of pervious concrete pavement (PCP) followed by a bamboo bioretention basin (BBB) with Dracaena sanderiana for urban stormwater volume control and water quality enhancement. Two PCPs (nPCP and tPCP) having a permeability of ∼4.5mm/s were prepared with optimized mix designs. A control impervious concrete pavement (CP) was also prepared. Results showed that both PCP-BBB’s outperformed CP-BBB not only in runoff volume reduction, but also in pollutant removal; both PCPs removed a considerably high amount of pollutants, especially in fecal coliform and phosphate removal. tPCP-BBB improved water quality better than nPCP-BBB in terms of chemical oxygen demand and pH. Additionally, D. sanderiana grew healthier in tPCP-BBB than in nPCP-BBB. Production costs for tPCP and CP were similar, whereas nPCP production was twice as expensive.

Mix design and pollution control potential of pervious concrete with non-compliant waste fly ash

Pervious concrete mix was optimized for the maximum compressive strength and the desired permeability at 7 mm/s with varying percentages of water-to-binder (W/B), fly ash-to-binder (FA/B), nano-iron oxide-to-binder (NI/B) and water reducer-to-binder (WR/B). The mass ratio of coarse aggregates in sizes of 4.75–9.5 mm to the binder was fixed at 4:1. Waste FA used in the study was not compliant with a standard specification for use as a mineral admixture in concrete. One optimum pervious concrete (Opt A) targeting high volume FA utilization had a 28-day compressive strength of 22.8 MPa and a permeability of 5.6 mm/s with a mix design at 36% W/B, 35% FA/B, 6% NI/B and 1.2% WR/B. The other (Opt B) targeting a less use of admixtures had a 28-day compressive strength and a permeability of 21.4 MPa and 7.6 mm/s, respectively, at 32% W/B, 10% FA/B, 0.5% NI/B and 0.8% WR/B. During 10 loads at a 2-h contact time each, the Opt A and Opt B achieved the average fecal coliform removals of 72.4% and 77.9% and phosphorus removals of 49.8% and 40.5%, respectively. Therefore, non-compliant waste FA could be utilized for a cleaner production of pervious concrete possessing a greater structural strength and compatible hydrological property and pollution control potential, compared to the ordinary pervious concrete.

Reactor performance and pathogen removal during wastewater treatment by vermifiltration

The application of vermifiltration could reduce the load of chemical and biological pollutants present in wastewater, reducing the pressure over water requirements and allowing the reclamation of the treated water. In the present study, vermifiltration has shown a great potential for chemical pollutants and pathogen removal in wastewater through the synergistic interactions of earthworms and microorganisms. The results of a pilot-scale study showed a higher percentage removal of biochemical oxygen demand (88%), chemical oxygen demand (78%), total suspended solids (83%) and log removal of fecal coliforms (2.61), fecal streptococci (2.50), Salmonella (2.20) and Escherichia coli (2.48) to the levels considered acceptable for reuse in irrigation purposes. Specifically, earthworms in the vermifilter were able to transform insoluble organic material to soluble form followed by selective digestion of the material to finer size, and further degradation by the microorganisms in the reactor. In vitro antimicrobial assay tests also showed that the present microflora had strong inhibitory efficiency against Staphylococcus aureus, E. coli, Pseudomonas aeruginosa and Klebsiella aerogenes. The observed inhibitory effect was found to be responsible for the phenomenon mentioned above, with release of antimicrobial substances by earthworms and associated microflora that showed antimicrobial potency against pathogenic bacteria. The kinetics evaluation showed the predominance of a first order removal model during vermifiltration.

EFFECT OF CLAY SOIL CONTENT ON FECAL BACTERIA REMOVAL IN AN INTERMITTENT MEDIA INFILTRATION SYSTEM

Water scarcity, the degradation of freshwater resources, and wastewater pollution are reaching crisis levels, especially in arid regions of the world. The reuse of wastewater was investigated by using intermittent media infiltration (IMI) to evaluate fecal coliform (FC) removal efficiency. Twelve IMI columns were packed with soil and natural filtering materials (sand, zeolite, vermicompost and charcoal) at percentages of 25, 50 and 75. The municipal wastewater was treated for the FC analysis for four weeks. The chemistry, physics, and morphology of the filter media as related to FC reduction were determined and characterized. Fine particle size and adsorption capacity are important factors for retaining FCs. The mixture of clay soil and filter media in a ratio of 75/25 gave the best performance for FC removal, and the average FC reductions for sand, zeolite, vermicompost and charcoal were 94.4%, 82.2%, 93.8% and 99.6%, respectively. The IMI of soil/charcoal gave a higher log removal (2.19-2.46 log) than the other media, and the effluent complied with Mexican regulations for unrestricted agricultural irrigation. These results showed good performance for FC removal and strengthened the possibility of using reclaimed municipal wastewater in unrestricted irrigation.

Reduction of waterborne microorganisms in treated domestic wastewater for reuse in agriculture: Comparison between floating media filter and sand filter

ABSTRACT This study aims to investigate the use of a floating media filter (FMF) to eliminate waterborne microorganism in treated domestic wastewater for reuse in agriculture. A conventional sand filter (SF) was used concurrently to compare treated water quality. The total/fecal coliforms and somatic coliphage were employed as fecal indicators. The result showed that the FMF was fed with 3 times higher infiltration rate (15 m 3 /m 2 .h) than that in the SF (5 m 3 /m 2 .h), in which both filters gave similar coliform removal at 6 hours operation. The somatic coliphage elimination tended to increase with operational time for the FMF while that of the SF showed decreasing trend. When a 24 hour continuous operation was applied for the FMF, it showed better removal of somatic coliphage (78%), fecal coliforms (60%) and total coliforms (56%) than that of 6 hour operation. In conclusion, the FMF gave better performance than the SF did by producing a good quality of treated water for agriculture in terms of waterborne microorganisms including turbidity and suspended solids.

Assessment of microbial viability in municipal sludge following ultrasound and microwave pretreatments and resulting impacts on the efficiency of anaerobic sludge digestion.

A range of ultrasonication (US) and microwave irradiation (MW) sludge pretreatments were compared to determine the extent of cellular destruction in micro-organisms within secondary sludge and how this cellular destruction translated to anaerobic digestion (AD). Cellular lysis/inactivation was measured using two microbial viability assays, (1) Syto 16® Green and Sytox® Orange counter-assay to discern the integrity of cellular membranes and (2) a fluorescein diacetate assay to understand relative enzymatic activity. A range of MW intensities (2.17-6.48 kJ/g total solids or TS, coinciding temperatures of 60-160 °C) were selected for comparison via viability assays; a range of corresponding US intensities (2.37-27.71 kJ/g TS, coinciding sonication times of 10-60 min at different amplitudes) were also compared to this MW range. The MW pretreatment of thickened waste activated sludge (tWAS) caused fourfold to fivefold greater cell death than non-pretreated and US-pretreated tWAS. The greatest microbial destruction occurred at MW intensities greater than 2.62 kJ/g TS of sludge, after which increased energy input via MW did not appear to cause greater microbial death. In addition, the optimal MW pretreatment (80 °C, 2.62 kJ/g TS) and corresponding US pretreatment (10 min, 60 % amplitude, 2.37 kJ/g TS) were administered to the tWAS of a mixed sludge and fed to anaerobic digesters over sludge retention times (SRTs) of 20, 14, and 7 days to compare effects of feed pretreatment on AD efficiency. The digester utilizing MW-pretreated tWAS (80 °C, 2.62 kJ/g TS) had the greatest fecal coliform removal (73.4 and 69.8 % reduction, respectively), greatest solids removal (44.2 % TS reduction), and highest overall methane production (248.2 L CH4/kg volatile solids) at 14- and 7-day SRTs. However, despite the fourfold to fivefold increases in cell death upon pretreatment, improvements from the digester fed MW-pretreated sludge were marginal (i.e., increases in efficiency of less than 3-10 %) and likely due to a smaller proportion of cells (10-20 %) in the polymeric network and mixed sludge fed to digesters.

Sewage-fed aquaculture: a sustainable approach for wastewater treatment and reuse.

This study assesses the long-term sustainability for operation and maintenance (O&M) of sewage-fed aquaculture-based sewage treatment system. The study focused on the integrated assessment of an engineered pond system of 8 million liters per day capacity in the city of Karnal, the State of Haryana, northern India. Major areas during the assessment included health, environmental, societal and institutional views aspects as well as the quality of treated effluent subjected for reuse. The treatment facility met the Indian regulatory standards (downstream reuse and discharge into the legally permitted water bodies) in terms of physical-chemical parameters. The total coliform and faecal coliform removal were up to 2-3 log units; nevertheless, it was not capable to come across the bacterial count requirement (<1,000 per 100mL to minimise human health risk in aquaculture practices). The system was able to generate sufficient net income required for routine O&M. Annual revenue collected by the Municipal Corporation from the lease of the facility as well as selling of treated wastewater was $3,077 and $16,667-$25,000, respectively. The additional benefit from the facility for the farmers included the saving of fertilizers and cheapest source of water available for irrigation. Recycling of treated sewages for irrigation is also returned nutrients to the surrounding farms in Karnal. This exercise has saved significant quantities of chemical fertilizer (26-41Ton of nitrogen, 10-18Ton of phosphorous and 38-58Ton of potassium per year) and the overall benefit for farmers during cultivation of one acre of crop was calculated to be approximately $133 per year.

Fecal Coliforms and Total Coliforms Removal in Water Using Radio-Frequency (RF) Plasma System

A radio-frequency plasma system (RF) was used to investigate the removal of microorganisms from water.Plasma generated by RF radiation can produce active compounds (H•, •OH, H2O2, O3, etc.) that have a highoxidation potential and can kill microorganisms present in water (fecal coliforms and total coliforms). Thefrequency of the plasma system was set to 3.0, 3.3 and 3.7 MHz and applied to river water for 60 minutes. Theresults show that in all runs, the pH of the water produced was in the range from 7.4 to 7.9. The removalefficiencies of fecal coliforms achieved were between 83.75 and 95% and were higher than the removalefficiencies of total coliforms, which were between 82.61 and 93.48%. Meanwhile, the death rate (kD) of fecalcoliforms wasfaster than that of total coliforms. Therefore, the removal of total coliforms is the key to removingmicroorganisms fromwater. RF plasma treatment can be used for treatment of drinking water to decreasemicroorganisms.

A new model for the prediction of the performance of integrated solar and hydraulic jump enhanced waste stabilization pond

This paper presents a model which incorporates: characteristic length, dispersion coefficient, supercritical inlet velocity, initial and final bacteria density before and after irradiation, first-order rate constant for fecal coliform removal, retention time, dispersion number, solar radiation, depth of the integrated solar and hydraulic jump enhanced waste stabilization pond (ISHJEWSP), length of the horizontal section of ISHJEWSP, and angle of slope of the ISHJEWSP. A comparison of the conventional waste stabilization pond and the ISHJEWSP showed that the bacteria removal was significantly higher in the enhanced pond than the conventional pond at a significance level of 0.05. The verification of the conventional model gave good average coefficients of correlation of R = 0.800±0.173 between the measured and calculated Ne/No and R = 0.924±0.034 for the ISHJEWSP, respectively.

Optimum mix design of fly ash geopolymer paste and its use in pervious concrete for removal of fecal coliforms and phosphorus in water

Mix ratios of liquid-to-binder (L/B), fly ash-to-binder (FA/B), nanoSiO2-to-binder (NS/B) and NaOH concentration (NH) of fly ash-nanoSiO2-cement geopolymer pastes were optimized for the flow of paste and the compressive strength simultaneously. Optimum mix design was found at 50% L/B, 60% FA/B, 0.04% NS/B and 1.71M NH resulting in a maximum achievable compressive strength at 22.2MPa after a 7-day curing under ambient temperature (25±5°C) and the desired flow of paste at 110%. It was found that NH had the greatest effect on the flow of paste: the higher NH, the smaller the flow of paste was. On the other hand, NS/B showed the least effect on the compressive strength. Pervious geopolymer concrete made with the optimum mix was able to reduce fecal coliforms and phosphorus by 54–100 and 25–85%, respectively, depending on the contact time (0.5–8h). A greater FC and P removal % was achieved at a higher pH caused by pervious geopolymer concrete.

Removal of bacterial contaminants and antibiotic resistance genes by conventional wastewater treatment processes in Saudi Arabia: Is the treated wastewater safe to reuse for agricultural irrigation?

This study aims to assess the removal efficiency of microbial contaminants in a local wastewater treatment plant over the duration of one year, and to assess the microbial risk associated with reusing treated wastewater in agricultural irrigation. The treatment process achieved 3.5 logs removal of heterotrophic bacteria and up to 3.5 logs removal of fecal coliforms. The final chlorinated effluent had 1.8 × 102 MPN/100 mL of fecal coliforms and fulfils the required quality for restricted irrigation. 16S rRNA gene-based high-throughput sequencing showed that several genera associated with opportunistic pathogens (e.g. Acinetobacter, Aeromonas, Arcobacter, Legionella, Mycobacterium, Neisseria, Pseudomonas and Streptococcus) were detected at relative abundance ranging from 0.014 to 21 % of the total microbial community in the influent. Among them, Pseudomonas spp. had the highest approximated cell number in the influent but decreased to less than 30 cells/100 mL in both types of effluent. A culture-based approach further revealed that Pseudomonas aeruginosa was mainly found in the influent and non-chlorinated effluent but was replaced by other Pseudomonas spp. in the chlorinated effluent. Aeromonas hydrophila could still be recovered in the chlorinated effluent. Quantitative microbial risk assessment (QMRA) determined that only chlorinated effluent should be permitted for use in agricultural irrigation as it achieved an acceptable annual microbial risk lower than 10−4 arising from both P. aeruginosa and A. hydrophila. However, the proportion of bacterial isolates resistant to 6 types of antibiotics increased from 3.8% in the influent to 6.9% in the chlorinated effluent. Examples of these antibiotic-resistant isolates in the chlorinated effluent include Enterococcus and Enterobacter spp. Besides the presence of antibiotic-resistant bacterial isolates, tetracycline resistance genes tetO, tetQ, tetW, tetH, tetZ were also present at an average 2.5 × 102, 1.6 × 102, 4.4 × 102, 1.6 × 101 and 5.5 × 103 copies per mL of chlorinated effluent. Our study highlighted that potential risks associated with the reuse of treated wastewater arise not only from conventional fecal indicators or known pathogens, but also from antibiotic-resistant bacteria and genes.

A Review of the Mechanisms of Faecal Coliform Removal from Algal and Duckweed Waste Stabilization Pond Systems

The use of eco-technologies for wastewater treatment such as algal and duckweed-based pond systems is becoming popular in developing countries owing to its affordability and efficiency of pathogen removal in warm climates. The pathogen removal mechanisms of these treatment systems however is still not clearly understood and existing knowledge is also scattered in journals and books of different disciplines. The purpose of this paper is to provide a concise review of knowledge acquired in recent times on faecal coliform removal mechanisms in algal and duckweed ponds in a comparative way while identifying knowledge gaps that still exist. This review pays particular attention to little known removal mechanisms such as the role of algal biomass, attachment and sedimentation of faecal coliforms and the role of predation by macro-invertebrates and protozoans. Recent experiments showed that algal ponds, in comparison with duckweed ponds, are more efficient in faecal coliform removal due to the high pH and oxygenation that occur in the former and the rate of inactivation of faecal coliforms increases with increased algal biomass till a certain optimum concentration after which it decreases. This optimal algal concentration for maximum destruction of faecal coliforms can be affected by the quality and strength of the wastewater. Algae also appeared to have a destructive effect on faecal coliforms even in darkness, a phenomenon that may be the effect of toxic substances from the algae. Results also show that the role of invertebrates, particularly macro-invertebrates may be more important in duckweed pond systems. Removal of faecal coliforms through attachment and sedimentation in both duckweed and algal ponds appear to be dependent largely on concentrations of faecal coliforms present and to some extent on suspended plant and particulate matter concentrations. Wide variations in removal efficiencies were however observed. We conclude that the wide variations in removal efficiencies can be addressed by standardizing operating conditions of treatment systems. Further work is necessary to identify the substances produced by algae which appeared to be toxic to faecal coliforms as well as establishing the relative importance of predation by protozoans and macro-invertebrates in the removal of faecal coliforms.

Developing an Integrated Sustainable Sanitation System for Urban Areas: Gaza Strip Case study

A vertical flow (reed bed) constructed wetland was used for treating bio-solid and gray water. The results present a positive performance in treating the bio-solids and well-stabilized accumulated organic material in the bed formed fertile soil. Moreover, using vertical flow reed bed of liquid waste treatment showed removal of around 70% of organic matter indicator Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD). The Fecal Coliform (FC) removal was around 2 logs (99.9%) with a retention time of less than two days. The effluent can be used in agriculture or groundwater recharge. A semi-dry toilet followed by anaerobic/aerobic units is in planning to be coupled with an existing system. The system mainly depended on separating of the human excreta from the urine and gray water. The two separated fractions will be treated in vertical flow reed bed to produce organic fertilizer and reclaimed water for reuse. Such systems could be a suitable solution for wastewater problems in Gaza strip and similar regions. The designed and planned system integrated environmental and technical sound approaches with socio- economical aspects. In addition, the designed system implemented the idea of a natural and closed circle of water and nutrients “from food to food”.

Alkaline disinfection of urban wastewater and landfill leachate by wood fly ash.

Wood fly ash is an industrial by-product of the combustion of different wood materials and is mostly disposed of as waste on landfills. In our preliminary experiments, wood ash exhibited antibacterial activity against urban wastewater bacteria and we focused on wood fly ash as a potential substrate for wastewater disinfection. The addition of ash at a concentration of 10 g L⁻¹ (1%) caused an instant increase of pH in urban wastewater and landfill leachate. High pH (10.1-12.7) inactivated bacterial populations in the wastewater and the removal of faecal coliforms and intestinal enterococci after 6 h of contact was 100% (below the detection limit; <1 CFU per mL) with the most efficient ash sample (ash from combustion of beech) both in urban wastewater and landfill leachate. Properly chosen wood fly ash, i.e. one that tends to increase the pH to the greatest extent, proved to be a very effective disinfection substrate. Considering that water treated with wood ash has a high pH and needs to be neutralised before discharge, ash would be suitable for disinfection of leachates when smaller volumes are treated.

Levantamiento batimétrico de la plata de tratamiento de aguas residuales de Neves Paulista

&lt;p&gt;Las lagunas de estabilización son uno de los sistemas naturales para tratamiento de aguas residuales más adecuados para reducir los impactos ambientales por vertimiento de efluentes en países en vías de desarrollo. La presente investigación tuvo como objetivo diagnosticar la acumulación de lodos y evaluar el desempeño de la planta de tratamiento de aguas residuales de la ciudad Neves Paulista (São Paulo, Brasil). Mediante un estudio batimétrico de las lagunas de estabilización anaerobia y facultativa se determinaron los perfiles y volúmenes de acumulación de lodos; se midieron diversos parámetros de la calidad del agua afluente y efluente, así como el caudal entrante durante 24 horas consecutivas. La batimetría indicó que los lodos acumulados redujeron los volúmenes útiles de las lagunas anaerobia y facultativa en 26,4% y 23,7% respectivamente y que su heterogénea distribución en las unidades de tratamiento afectó su desempeño hidráulico. La eficiencia media de remoción de la DBO fue del 76,6%, inferior a la mínima establecida por la legislación ambiental brasilera. El número más probable de coliformes fecales en el efluente fue de 6,34x10&lt;sup&gt;5&lt;/sup&gt;/100mL, que superó en gran medida los valores máximos permitidos para vertimientos en cuerpos receptores. La planta requiere de la implementación de un sistema de pre-tratamiento, de la remoción de los lodos acumulados en las zonas más críticas y la implementación de un sistema de postratamiento que garantice remoción adicional de DBO y coliformes para ajustarse a la normatividad ambiental. &lt;/p&gt;

Treatment of domestic wastewater using modified septic tank

The treatment of domestic wastewater using conventional, single-baffle, two-baffle, and packed-type septic tanks was the main theme of the present study. The septic tanks were fed continuously with domestic wastewater at three hydraulic retention times (HRTs), ranging from 24 to 72 h. The average characteristics of raw domestic sewage investigated in this study in terms of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) were 960, 450, and 295 mg/l, respectively. The product quality of the treated domestic wastewater by the four types of septic tanks in terms of physicochemical and biological characteristics proved to be satisfactory. Comparison wise, better results were obtained using the packed-type septic tank for primary treatment. The average removal of pollutants for each type of septic tank in terms of COD, BOD, and TSS improved in direct proportion to HRT. The fecal coliform removal values were affected by the type of the septic tank and the HRT. The highest percentage removal reached only one log. The accumulated sludge volume and weight were found to be dependent on the septic tank type and HRT. The average percentage of sludge volatile organic matters was almost equal. At each HRT, the due time for tank desludging was observed to be in order of conventional > single-baffle > packed-type > two-baffle septic tank. Based on the achieved results, either the two-baffle or the packed-type septic tank is considered to be a viable solution for the on-site decentralized treatment of high-strength domestic wastewater, especially at rural communities.

Electrochemical oxidation of activated sludge by using direct and indirect anodic oxidation

The electrochemical oxidation of activated sludge (EOAS) was studied by direct anodic oxidation on the surfaces of stainless steel and graphite electrodes as well as by indirect anodic oxidation on Pb/PbO2 surface. The effects of several operating parameters such as current density, charge passed, initial pH, mixing speed, and configuration, and position of electrodes on the removal rate of chemical oxygen demand (COD), total and fecal coliform were investigated. The experimental data indicated that COD removal rates were, respectively, 66.9 and 77.5% in direct and indirect methods. The results also showed that the Pb/PbO2 electrode through indirect electrooxidation mediated based on the electrogeneration of physisorbed hydroxyl radical and other oxidants like active chlorine has higher mineralization rates and consumes the least energy. Over 99% of total and fecal coliform was removed, which is mainly attributed to electrogeneration of hypochlorite and chloride ions in the aqueous solution. Kinetic trend of COD and total and fecal coliform removal for Pb/PbO2 electrode were obtained. In order to better function of EOAS, selection of suitable mixing speed and configuration and position of electrodes are essential.

EFEITO DA MASSA E DA FORMA DE PROCESSAMENTO DAS SEMENTES NO PODER COAGULANTE DA MORINGA - DOI: 10.13083/1414-3984.v22n04a06

Pouco se sabe sobre a influência da qualidade e da forma de processamento da semente no poder coagulante do extrato de sementes de moringa. Assim, a realização deste trabalho objetivou avaliar o poder coagulante e xenobiótico das sementes de acordo com a faixa de massa e a sua forma de processamento (descascadas e não descascadas) para preparo do coagulante. Para isso, analisou-se a água superficial com alta turbidez coletada em uma represa. Nas amostras foram adicionados extratos preparados com sementes divididas em três classes de massa (menor ou igual a 0,20 g, entre 0,20 e 0,30 g, e maior ou igual a 0,30 g); sementes descascadas, sem discriminação de massa; e&#x0D; apenas cascas; além da testemunha (sem adição de coagulante). Além disso, foram analisados os teores de nitrogênio e proteína no material. Os resultados indicaram que as maiores eficiências na remoção da turbidez e de coliformes termotolerantes (E. coli) estão associadas ao teor de proteína bruta nos materiais utilizados no preparo do extrato. Aumento na coagulação/floculação/sedimentação de sólidos e na remoção de coliformes foram obtidos com a adição de extratos preparados com sementes de massa maior que 0,20 g, ou com sementes descascadas. No que se refere às sementes de massa menor que 0,20 g, maiores eficiências na remoção de turbidez e coliformes são obtidas quando os extratos são preparados com sementes descascadas.

Dinâmica da população de coliformes durante a compostagem automatizada de dejetos líquidos de suínos

Microrganismos presentes em dejetos de suínos podem contaminar o meio ambiente. Embora a compostagem seja preconizada como um método eficiente para reduzir este potencial poluidor dos dejetos, existem poucas informações de pesquisa sobre tal processo. O presente trabalho teve o objetivo de avaliar a eficiência da compostagem automatizada dos dejetos líquidos de suínos (DLS) na redução da população de coliformes, usados como indicadores de poluição fecal. Os DLS foram adicionados periodicamente, durante 106 dias, em substrato constituído pela mistura, em partes iguais, de maravalha e serragem. Foram efetuadas 14 adições de DLS, e em cada adição as leiras de compostagem eram revolvidas por meio de uma máquina especialmente desenvolvida para este fim. Foram avaliados dois tratamentos com três repetições, sendo um com e outro sem adição de ácido fosfórico aos dejetos, até pH 6,0. A adição de ácido visou reduzir as perdas de N por volatilização de amônia (NH3) durante a compostagem. A avaliação da população de coliformes foi feita pela técnica do número mais provável (NMP), com uso do caldo Fluorocult, incubado a 37ºC por 24h e posterior leitura em luz ultravioleta. A população de coliformes fecais não foi afetada pela adição de ácido fosfórico. O processo de compostagem automatizada foi eficiente na redução de coliformes fecais, cuja população original passou de 4,2x1010 para 1,2 x 105 ao final da compostagem (156 dias) sem adição de ácido e de 3,8x1010 para 2,3x104 na compostagem com adição de ácido. Essa remoção de coliformes fecais, promovida pela compostagem automatizada dos dejetos líquidos de suínos, corresponde a 99,99 %.