Search results

Examines the potential for excessive crop uptake of nutrients, soil mineralization, and response of livestock to the usage of Ogunpa Stream, Ibadan, Nigeria. A number of surface water and soil samples were collected from the Ogunpa and small irrigated farms near the stream for physico‐chemical examination. Results show that the stream is suitable for irrigated agriculture but not for aquaculture and livestock breeding especially in the middle reaches. The added nutrients accumulated in the cultivated layer of the soil. There was some evidence of migration of some elements down from the cultivated layer. The potential hazard for pollution caused by irrigating with the polluted water threatens crop and vegetables grown on adjacent farms as well as groundwater of the nearby area. This may seriously affect the consumers. It is recommended that residents around the stream become aware of how to reduce the pollution level.

The purpose of this paper is to evaluate the efficiency of a duckweed pond in the polishing of a stabilization pond effluent, as well as quantify its biomass production. Once an adequate destination is given to the produced biomass, the wastewater treatment plant can work in a sustainable and integrated way.

The duckweed pond consisted of a tank with volume 0.44 m³, operating in continuous flow with an outflow of 0.12 m³/day and hydraulic retention time of 3.8 days. Effluent samples were collected before and after the treatment, with analyzes made: daily-pH, dissolved oxygen and temperature; twice a week – total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD); and weekly – total solids (TS) and Biochemical Oxygen Demand (BOD₅). The duckweeds were collected each for seven days for its production quantification.

The highest efficiency of TN, TP, COD, BOD₅ and TS removal were of 74.67, 66.18, 88.12, 91.14 and 48.9 percent, respectively. The highest biomass production rate was 10.33 g/m²/day in dry mass.

There was great variation in biomass production, which may be related to the stabilization pond effluent conditions. The evaluation of the effluent composition, which will be treated with duckweeds, is recommended.

The evaluated treatment system obtained positive results for the reduction in the analyzed variables concentration, being an efficient technology and with operational simplicity for the domestic effluent polishing.

The motivation of this work was to bring a simple system of treatment and to give value to a domestic wastewater treatment system in a way that, at the same time the effluent polluter level is reduced and it is also possible to produce biomass during the treatment process.

Carries out an investigation to evaluate the performance of the maturation pond, one of an aerated oxidation pond system at the Mit Mazah Sewage Treatment Plant (Daquahliya Governorate, Egypt), with respect to phytoplanktonic structure and nutrient elimination during different seasons. Details how the study collected composite water samples from the maturation pond at monthly intervals. Observes that there are substantial changes in the distribution pattern of the algal community structure during different seasons. Concludes that to obtain considerable algal biomass in the maturation pond, the pond system must be subjected to performance control.

The purpose of this paper is to assess the occurrence and risk of dispersion in the environment of antibiotic-resistant microorganisms from sanitary sewage sludge produced in two conventional wastewater treatment systems adopted in the West of the State of Paraná, Brazil.

The sludge samples were collected for three months from two wastewater treatment plants, totaling six sample points, and sent to the laboratory where the physical-chemical and biological determinations were performed.

This work made possible to find that the sludge produced in the sewage treatment plants presents potential risks related to the spread of microorganisms due to the occurrence of resistant isolates of Escherichia coli and Salmonella sp. It was also possible to detect that the largest concentrations of metal ions in the sludge favored the occurrence of bacterial resistance to antibiotics. The occurrence of pathogens, heavy metals and other emerging pollutants in sewage indicates that the sludge requires proper treatment, to provide safe agricultural reuse or disposal.

The techniques applied for monitoring sludge were effective to check the risk of resistant microorganisms input into the environment. Studies concerning sewage treatment plants’ final effluents can bring additional data about the incorporation of such microorganisms into aquatic environments.

The results made possible to observe the need to provide post-treatment for the sludge, especially of the sludge obtained from the anaerobic fluidized bed reactor, since the removal of pathogens, as well as the nutrients, is not satisfactory.

Many countries all over the world are facing water shortages. As population increases, water is being perceived as a very valuable resource. Every effort is exerted to use water more efficiently and to make use of every drop of water to ensure the well being of future generations. New trends are developed and practiced in the area of water resources use and water saving. These trends vary from one country to another according to the degree of water scarcity, economic situations, and other factors. Developing non‐conventional water resources is an example of the recent trends in developing new water resources and water savings. Unlike rainfall, rivers, and groundwater which are considered conventional freshwater resources, the non‐conventional water resources include sea water desalination, agriculture wastewater reuse, and municipal wastewater reuse. This paper deals with the reuse of agriculture, municipal, and industrial wastewater as a new trend in developing additional water resources. Special interest is given to municipal wastewater, its characteristics and necessary treatment. Environmental and human health considerations for wastewater reuse, especially in agriculture, are also discussed. Possible consequences of wastewater reuse are introduced. Examples of wastewater reuse practices in some countries are also mentioned.

The main purpose of this study is to investigate the bioaccumulation pattern and fate of heavy metals in duckweed‐based wastewater treatment ponds with different depth.

Three replicates of four reactors were used in this experiment. The reactors were randomly distributed on the bench and filled with 50 percent diluted sewage for the control reactors whereas diluted sewage mixed with 5 mg Pb/l and 5 mg Zn/l was used for the treatment reactors. The reactors were stocked with Lemna gibba at 1,000 g fresh weight per each square meter. The culture tanks were exposed to temperature range of 21‐25°C and light regime of 16 hours light using halogen lamps and 8 hours dark. The light intensity was maintained around 200 μ E m⁻² S⁻¹. The experiment extended for 30 days. Regular monitoring of the growth performance of duckweed was carried out with subsequent analysis of dry matter, heavy metals, phosphorous and nitrogen content. Composite samples from the water phase were subjected to the analysis of ammonia, nitrite, nitrate, orthophosphate and sulfate concentration. The analysis of sediment and biofilm were carried out at the end of the experiment. Interpretation of results was carried out using one‐way analysis of variance.

Statistical analysis showed a significant reduction in the growth rate of duckweed within the first five days exposure time. After five days exposure, the growth rate in the treatments returned to the normal growth till day 15 after which the growth became significantly lower in the small and medium scale ponds. The results revealed that zinc is more bio‐available than lead and both metals are mostly precipitated in the sediment probably as sulfides.

The results help in enhancement of heavy metals removal in a small anaerobic pretreatment unit before entering to the pond system by sulfate addition.

The results of the study confirm the positive effect of pond depth in reducing the heavy metal toxicity to the duckweed‐based wastewater treatment ponds.

Purpose – This study aims to obtain the best lipid content in locally isolated microalga that grows in palm oil mill effluent (POME).

Design/Methodology/Approach – Microalgae were cultured in POME with 25% dilution (LP₂₅), 50% (LP₅₀), and no dilution (LP) in 1,500 ml glass vessel at room temperature using a lighting intensity of 13,000 lux and continuous aeration for 24 hours and 12 hours, respectively. The biomass (in dry weight) of microalgae was analyzed daily by means of spectrophotometry using 624 nm wavelength to determine their growth.

Findings – The results showed that the acclimatized growth of microalgae in POME media adapted faster to the POME concentration. Acclimatized biomass content tends to increase to 1.014 g/L, while the content of non-acclimatized biomass reached only 0.752 g/L. Lipid content resulting from the direct extraction process using the modified Bligh and Dyer method provided the best yield of 47% in the microalgae grown in the LP₅₀ POME medium.

Research Limitations/Implications – Lipid was produced from locally isolated microalgae cultured in POME medium with 25% dilution (LP₂₅), 50% (LP₅₀), and no dilution (LP).

Practical Implications – The lipid produced had the potential for biodiesel energy.

Originality/Value – In this study, microalga was used not only to treat POME liquid wastes but also to produce lipids as biodiesel energy potentials.

The goal of this paper is to detect helminth eggs in treated wastewater for sanitary control, using them as biological indicators of wastewater quality.

Samples were taken from the Municipal Wastewater Treatment Plant of the Metropolitan Area. To concentrate the samples, centrifugation‐flotation on 33 percent zinc sulphate was applied.

The study revealed the constant presence of helminth eggs as Ascaris sp., Enterobius sp., Hymenolepis sp., and Strongyloides sp.

The results indicate that helminth eggs can be used as bioindicators for sanitary control of treated wastewater to be reused in urban areas.

Urban population growth has increased pressure on natural resources, water in particular. It has resulted in serious water stresses, poor waste management and severe diffuse pollution. To achieve more favourable solutions, there is a need to look for technological alternatives based on the principles of closing cycles. Incorporation of the agricultural system to the sanitary system with nutrient recycling is one of the major ways of closing the loops in urban and peri‐urban areas. However, various partnerships with all actors of the civil society should be established. Development and implementation of successful reuse operations require more research work to define urban models in which material cycles are closed at affordable economic costs. This paper aims at discussing alternative water management approaches to ensure environmentally sound urban and peri‐urban water‐related relationships.