Effluent Disposal Research Articles

Managing Water and Wastewater Services in Finland, 1860–2020 and Beyond

Water and wastewater services are invaluable for communities. The aim of this article is to understand and explain the overall long-term development of water services in Finland in the wider PESTEL framework with policy implications for the future. The original megastudy was based on an extensive literature review. The article first covers the birth and development of urban and rural water systems in Finland. This is followed by analysing selected decisions with long-term impacts, institutional issues, discussion and lessons learnt, and conclusions. The development of water services in Finland has largely been based on trust. In socio-institutional factors, institutional diversity is fundamental. Gradual expansion of water supply and wastewater systems has brought technical, economic and social benefits in a country with quite a dispersed population. Efficient water pollution control in communities was implemented within two decades through developing technology and applying proper legislation and control. Continuous and dynamic development has been a key principle. Nature-based solutions include raw water source selection, treatment processes such as managed aquifer recharge, sites for final effluents disposal, and water related land use planning. Aging infrastructure is the most pressing future challenge in Finland and worldwide and will need new requirements and innovations.

Adsorptive Sequestration of Toxic Congo Red Dye from Aqueous Solution Using Fe3O4/Sugarcane Bagasse Biochar Nanocomposite

In the current scenario, removal of toxic dyes from dye contaminated water has become a major challenging task to world researchers because disposal of untreated dye effluents into water bodies have adverse effect towards the ecosystem. Keeping this in mind, the present study aims to utilize the sugarcane bagasse biochar (SBB) and its composite with iron oxide nanoparticle (Fe3O4/SBB) to estimate for the decontamination their batch scale potential of Congo red (CR) dye from aqueous solution. The synthesized adsorbent were characterized by FT-IR, XRD, FE-SEM, TEM, VSM, EDX, and BET surface area analysis. The effect of adsorbent dosages (50-130 mg), initial CR concentration (10-100 mg/L), pH (3-11), and contact time (5-240 min) were evaluated CR removal on Fe3O4/SBB at room temperature. The adsorption data well fit with Langmuir isotherm (R2 = 0.99) and pseudo second order kinetics (R2 = 0.99). The maximum adsorption capacity was found to be 74.07 mg/g.

Industrial reuse of petrochemical effluents: A case study of ultrafiltration and reverse osmosis

The petrochemical industry uses high volumes of water in its production processes and generates effluents that have a great potential for reuse in production processes. The reuse of these effluents is, therefore, an alternative for the sustainable development of the sector. This study aimed at evaluating the application of ultrafiltration (UF) and reverse osmosis (RO) in the treatment of petrochemical effluents for the production of industrial reuse water, reducing environmental impacts caused by the disposal of effluents in the soil. The experiments were carried out with effluents named waste stabilization pond 1 (WSP-1), waste stabilization pond 8 (WSP-8) and an inorganic effluent (INO), which was used as feedwater in the pilot unit with a treatment capacity of 1 m³.h–1. The parameters chosen for evaluation in the treated effluents were calcium, magnesium, chloride, sulfate, electrical conductivity (EC), total organic carbon, color, chemical oxygen demand (COD), pH, total suspended solids and turbidity. Membrane permeate fluxes were determined to evaluate the performance of the pilot system. After treatment and characterization of each effluent, the results were compared to define the most suitable effluent to achieve the quality required for industrial reuse. The results showed that the proposed UF/RO treatment provided a stable flux for the WSP-8 effluent. Conversely, the other streams showed an accentuated decrease in flux, which indicates fouling processes of the UF and RO membranes. As for the efficiency of the treatment, the process removed compounds of interest such as COD above 90%, salts and EC above 92% for the three assessed effluents. Thus, considering all aspects evaluated in this study, WSP-8 was the most suitable to be used as feed in the pilot system with UF and RO. The permeate produced presented the necessary quality for reuse in the industries of the Southern Petrochemical Complex, presenting equivalent characteristics to those of clarified water. Thus, the reuse of treated petrochemical effluents may be an important alternative source of water resources in face of availability and scarcity restrictions in industries in southern Brazil.

Effects of Seasonal Variations on Microorganisms on Paint-Polluted Soil in Nigeria

Adverse impacts of paints effluents from industries improperly disposed into the environment caused pollution, a lot of carcinogenic, mutagenic, physiological alterations resulting in debilitating health effects on humans. The study was aimed at the effects of seasonal variations on soil microorganisms’ dominant at paint effluent disposal sites in lagos. A total of one hundred soil samples each were collected at different seasons of the disposal sites of two paint companies and analysed using standard microbiological methods. Results obtained shows paint effluents caused a significant decrease (p≤0.05) in the population of the microbial groups studied in the different seasons. Total heterotrophic bacterial population decreased from 7.7x108±0.19 to 6.4x107±0.01 in the dry season, and 5.3x108±0.08 to 6.5x107±0.15 during the rainy season. A total of eleven bacterial and eight fungal genera were identified. The identified bacterial genera included Bacillus, Pseudomonas, Staphylococcus, Micrococcus, Serratia, Arthrobacter., Aeromonas, Citrobacter, Alcaligenes, Flavobacterium, and Enterobacter. The fungal genera included Aspergillus, Penicillium, Fusarium, Mucor, Rhodotorula, Cladosporium, Trichophyton, and Geotricum. The most predominant bacteria and fungi were Bacillus (30.0%) and Pseudomonas (16,7%) species and Aspergillus (38.5%) species respectively. This study has confirmed the presence of different microbial species associated with acrylic paint-impacted sites. It, therefore, suggests that improvement of antimicrobial additives of paints may be a promising approach to reduce contamination.

Taxonomic diversity and predictive metabolic functions of a heavy metal tolerant multiple azo dye degrading bacterial consortium from textile effluents

Direct disposal of industrial dye effluents is a serious environmental menace. The bacterial population selected in response to dye contamination prominently participate in the dye detoxification process. We report multiple azo dye degradation activity of a bacterial consortium developed in the azo dye Congo Red (CR) supplemented medium. Degradation activity was most effective under static condition. Degradation of CR and other dyes at 2000 mg/L concentration ranged from 85 to 97% after 96–120 h except for Amido Black 10B showing 85% decolorization in 24 h. A 16S rRNA gene metagenomic analysis revealed high abundance of Proteobacteria, Bacteroidetes and Firmicutes in the consortium. The dominant bacterial genus were Acinetobacter, Comamonas, Erwinia, Trichococcus, Dysgonomonas, and Citrobacter. PICRUSt based functional analysis of the metagenome sequences predicted abundance of gene and protein families for mineralization of xenobiotic compounds. The predicted genes were mapped on KEGG pathway for construction of CR degradation pathway.

Development and validation of a fish-based index of biotic integrity for assessing the ecological health of Indian Rivers Mahanadi and Kathajodi-Devi

Abstract India has a vast network of 14 major rivers and their tributaries, covering 83% of the drainage basin and accounting for 85% of the surface flow. Anthropogenic activities like damming, channel modification, water abstraction, sewage and effluent disposal, sand mining, unthoughtful exploitation of biotic resources, etc. are the major threats faced by the rivers in the country. Monitoring protocol of Indian rivers lacks an integrated approach based on judicious use of both abiotic and biotic components as well as a total lack of consideration for ecological health. Index of Biotic Integrity is a flexible multimetric index that can be modified and adapted to the various zoogeographic regions of the world. A fish-based multi-metric IBI was developed by modifying and incorporating metrics that are sensitive to the various ecological stressors faced by Indian rivers, fishes being excellent indicators of river health. The adapted IBI was validated and used to assess ecological health of two rivers—Mahanadi, and its distributary Kathajodi-Devi—flowing through central-eastern India. The study indicated that in River Mahanadi, around 25% of the freshwater river stretch was slightly impaired and the remaining 75% stretch was moderately impaired. In Kathajodi-Devi, most of the river stretches were in a moderately impaired condition, except at Italnga stretch where the river was severely impaired. The Index of Biotic Integrity scores estimated could reflect the ecological health of the rivers. The study shows that use of Index of Biotic Integrity is a useful and reliable approach to assess the health conditions of Indian aquatic resources warranting initiatives to be taken to implement and incorporate it into the country's water resource management.

Controllable synthesis and adsorption mechanism of flower-like MoS2/g-C3N4 nanocomposites for the removal of methylene blue in water

The treatment of dye-bearing wastes by adsorption using low-cost synthetic adsorbents is urgently needed and challenging because it offers the dual benefit of water treatment and waste management. Herein, the flower-like MoS2/g-C3N4 nanocomposites with a size range of 200–400 nm and a specific surface area of 70.656 m2/g were synthesized as new methylene blue (MB) adsorbent materials. Their adsorption mechanisms and influences of pH, adsorbent dosage, concentration, and temperature on the adsorption properties were investigated by batch sorption experiments. Adsorption isotherm data were fitted with the Langmuir model, and the adsorption kinetic characteristics conform to the quasi second-order kinetic equation. According to thermodynamic data, methylene blue (MB) adsorption was endothermic and spontaneous, exhibiting a maximum adsorption capacity of 278.4 mg/g at 45 °C. Additionally, the impact of MB effluent on the germination of chickpea and wheat was studied contrastively with treatment of the tested materials. The results indicated that adequate adsorption of flower-like MoS2/g-C3N4 nanocomposite could potentially treat wastewater from the textile industry to be used for irrigation and solve the problem of textile effluent disposal.

Performance Upgrading Evaluation of the Anaerobic Baffled Reactor by Integrating Aerobic Media Filter for Municipal Wastewater Treatment

Background & Aims of the Study: Anaerobic baffled reactor (ABR) is one of the low-cost wastewater treatment systems; however, it has some limitations, such as insufficient standard nutrient outflow. Accordingly, it should be studied and developed. This research aims to determine the efficiency of a five-sectional reactor pilot and to upgrade it with an integrated aerated media filter in the reactor (integrated reactor) for municipal wastewater treatment. Materials and Methods: This study was performed on a laboratory scale with field conditions in the Khoy City wastewater treatment plant. The ABR reactor operated for 270 days with a hydraulic retention time (HRT) of 48, 36, 24, and 18 hours, respectively. The Integrated anaerobic baffled reactor (IABR) was operated for 35 days with 24 hours of HRT, i.e., aeration time of 5 hours. The reactors were fed in line from the inflowing wastewater to the treatment plant. A 24-hour combined sampling was performed 224 times from the inflow and outflow of the system, and volatile suspended solids, total kjeldahl nitrogen (TKN), total phosphorus (TP), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and Total Suspended Solids (TSS) parameters were measured and compared with the effluent disposal standard. Results: The launch of ABR lasted 105 days, and its helpful operation lasted 200 days. In 18 to 48 hours, the reactor removed 79% to 91% of COD, 9% to 20% of TKN, 19% to 30% of phosphorus, and 89% to 94% of TSS. The IABR reached the effluent disposal standard in terms of TSS, BOD, COD, and phosphorus under 24 hours HRT, i.e., aeration time of 5 hours, and increased the COD removal efficiency by 6% compared to ABR under 24 hours HRT and the same conditions. Conclusion: By integrating the final aerobic media filter in ABR while reducing the required HRT by 50%, its efficiency in achieving the effluent disposal standards increased compared to ABR. Therefore, this system can be used to treat municipal wastewater.

Feasibility of Producing Sodium Hypochlorite for Disinfection Purposes using Desalination Brine

On the Fernando de Noronha archipelago of northeast Brazil, the water supply comes from the desalination of seawater. The main environmental problem related to desalination is the brine resulting from the process, comprised of highly concentrated salts. The present study aimed to produce oxidant solutions from brine for disinfection purposes. The experiment was carried out on a laboratory scale. The brine had a chloride concentration of 40000 mg/L. The electrolysis process lasted twenty-four hours, monitoring pH, electrical conductivity, temperature, and chlorine. The sodium hypochlorite production was 2.27% and 3.61% m/m. The oxidant solutions were tested on domestic effluents and achieved a 99.99% removal rate of thermotolerant coliforms while maintaining the concentration of organochlorines below the upper limit established by legislation for the disposal of effluents. Therefore, the use and more proper brine disposal are sustainable alternatives, enabling the on-site production of sodium hypochlorite on the archipelago in a safe, effective, reliable way and comparable to other oxidants.

Equilibrium, Kinetic and Thermodynamic Studies of Malachite Green Dye Removal using Activated Sludge from Common Effluent Treatment Plant

Disposal of industrial effluents containing synthetic dyes causes a potential hazard to the land and environment and therefore dyes need to be removed before disposal. In the present study, combined effluent treatment plant (CETP) sludge was activated at 200° C for 1 hour and used as an adsorbent for the removal of malachite green dye from wastewater. The adsorbent was characterized by XRF, SEM, XRD and FTIR. Batch studies were carried out under various experimental conditions by varying contact time, dye concentration, adsorption dose, pH and temperature to assess the potentiality of activated sludge for the removal of malachite green dye from wastewater. The results revealed that the removal of malachite green dye was strongly pH dependent and maximum dye removal was observed at equilibrium pH of 8.0. Optimum adsorbent dose and contact time were found to be 10 g/l and 180 minutes respectively. Thermodynamic studies showed the spontaneous and endothermic nature of the adsorption. Adsorption data have also been correlated with different isotherm models. Hence activated sludge can be used as an effective adsorbent for the removal of malachite green dye from wastewater. It could be considered as good replacement of commercially available adsorbent like zeolites, activated carbon etc. due to its significant low cost and high sorption efficiency.

Hybrid of sodium polytungstate polyoxometalate supported by the green substrate for photocatalytic degradation of auramine-O dye.

Nowadays, textile industries have severely polluted the ecosystem and water sources via disposal of highly thermo- and photo-stable dyes within the ecology that require practical strategies to remove them from nature. In studies, the photocatalytic disinfection technique has been shown to have widespread applications in indoor air, environmental health, detection, biological, biomedical, laboratory hospital, pharmaceutical food industry, plant safety, waste water, effluents disposal, and drinking water disinfection. Herein, the sodium polytungstate (SPT) polyoxometalate (POM) was synthesized through a multi-step production procedure and hence modified via employing a green protocol by using tartaric acid, glutamic acid, and kombucha solvent toward efficient and total complete removal of the highly toxic, stable, and carcinogenic auramine-O (AO) dye from aqueous media. In this regard, developed materials were well-characterized, and their photocatalysis performance for photodegradation of AO dye was examined. Achieved results showed that the optimum absorption conditions were achieved at pH of 5.0, 15mg/L of AO concentration, 0.04g of photocatalyst dosage, and 110min irradiation time, where SPT and modified SPT via green protocol showed full desirability (desirability function (DF) index of 1) along with 71.75 and 100% removal percentage, respectively. Obtained results justified the superior photocatalytic role of the SPT POM and its derived nanocluster that can be used for the complete removal of highly stable dyes from aqueous media till reaching the drinking water standard.

Market Opportunities of Water Treatments Powered by Solar Micro Gas Turbines: Chile and Ecuador Case Studies

Throughout the last decades the developments on desalination field have been focused on energy consumption and costs reduction. However, water recovery and brine disposal are becoming a matter of concern to desalination industry. In this work, a Zero Liquid Discharge (ZLD) unit coupled with a Solar Micro Gas Turbine (SMGT) system is presented to address, among others, the challenges of mining industry in remote areas, in particular, fossil fuel dependence, water availability and pollution derived from effluents disposal. As a way to assess the feasibility of the proposal, a techno-economic analysis of the application in two Southern American regions (Chile and Ecuador) of photovoltaic modules, wind turbines and Solar Micro Gas Turbines is performed. Afterwards, the main novel feature of the new system—i.e., the ZLD unit—is described and a sensitivity analysis on its functioning whilst coupled with the SMGT is carried out. The aim is to propose a preliminary design of the ZLD process. The selection of the optimal ratio between exhaust gases and brine mass flow rates is analyzed, as well as variation in inlet salinity and temperatures. Furthermore, the water which could be recovered from effluents, at the same time that the heat of exhaust gases from SMGT is harvested, is quantified. Lastly, according to the results obtained, a preliminary design of a 10 kWe rated power SMGT system, coupled to Reverse Osmosis (RO) and ZLD units, is proposed.

A plant-wide model describing GHG emissions and nutrient recovery options for water resource recovery facilities

In this study, a plant-wide model describing the fate of C, N and P compounds, upgraded to account for (on-site/off-site) greenhouse gas (GHG) emissions, was implemented within the International Water Association (IWA) Benchmarking Simulation Model No. 2 (BSM2) framework. The proposed approach includes the main biological N2O production pathways and mechanistically describes CO2 (biogenic/non-biogenic) emissions in the activated sludge reactors as well as the biogas production (CO2/CH4) from the anaerobic digester. Indirect GHG emissions for power generation, chemical usage, effluent disposal and sludge storage and reuse are also included using static factors for CO2, CH4 and N2O. Global and individual mass balances were quantified to investigate the fluxes of the different components. Novel strategies, such as the combination of different cascade controllers in the biological reactors and struvite precipitation in the sludge line, were proposed in order to obtain high plant performance as well as nutrient recovery and mitigation of the GHG emissions in a plant-wide context. The implemented control strategies led to an overall more sustainable and efficient plant performance in terms of better effluent quality, reduced operational cost and lower GHG emissions. The lowest N2O and overall GHG emissions were achieved when ammonium and soluble nitrous oxide in the aerobic reactors were controlled and struvite was recovered in the reject water stream, achieving a reduction of 27% for N2O and 9% for total GHG, compared to the open loop configuration.

Concentration and Toxicological Risk Assessment of Heavy Metal Pollution in Dumpsite Soils within Benin City, Nigeria

Indiscriminate disposal of refuse and industrial effluents is a challenge in Nigeria. This poses a plethora of health and ecological risks from heavy metal contamination of soils. This study investigated the levels of heavy metal contamination in dumpsite soils and its effects on human health within Benin metropolis, Nigeria. The specific objectives were to determine the human and ecological risks via different exposure pathways. Soil samples were collected from three sampling stations, digested and analyzed for lead, cadmium, zinc, chromium, iron, nickel, manganese and copper using the Atomic Absorption Spectrophotometer (AAS). Pollution Indices and Human health risk were estimated using appropriate formulae. Results showed that that the mean concentrations of the investigated metals in the three stations were chromium (17.12±1.00, 17.65±1.05 and, 17.24±1.05 mg/kg), nickel (37.60±7.95, 40.98±1.46 and, 41.25±0.92 mg/kg), copper (48.57±4.91, 47.76±3.66 and, 48.05±3.46 mg/kg), lead (8.2±0.22, 8.17±0.52 and, 8.25±0.16 mg/kg), manganese (94.52±4.90, 94.98±6.69 and, 95.06±4.63), iron (467.98±36.69, 464.90±22.36 and, 462.15±10.64 mg/kg), cadmium (2.30±0.16, 2.22±0.11 and, 2.22±0.10 mg/kg) and zinc (142.93±3.93, 142.29±3.41 and, 142.87±3.86 mg/kg) respectively. Human health risk assessment revealed that the highest and lowest daily intake for the ingestion, inhalation and dermal pathway for both adults and children were Zinc and lead. Daily intake for children was higher than for adults via the three pathways with lifetime cancer risk (LCR) higher for children than adults. Carcinogenic and non-carcinogenic risk assessment shows that there were minimal risks from heavy metal contamination of the soils. Effective management and continuous monitoring of dumpsite soils is recommended to prevent negative impacts to man and the environment.

Plant-wide assessment of alternative activated sludge configurations for biological nutrient removal under uncertain influent characteristics

This study presents an extensive plant-wide model-based assessment of four alternative activated sludge (AS) configurations for biological nitrogen (N) and phosphorus (P) removal under uncertain influent loads and characteristics. Zeekoegat wastewater treatment plant (WWTP) in South Africa was chosen as case study due to its flexible design that enables operation in four different AS configurations: 3-stage Bardenpho (A2O), University of Cape Town (UCT), UCT modified (UCTM), and Johannesburg (JHB). A metamodeling based global sensitivity analysis was performed on a steady-state plant-wide simulation model using Activated Sludge Model No. 2d with the latest extension of physico-chemical processes describing the plant-wide P transformations. The simulation results showed that the predictions of effluent chemical oxygen demand (COD), N and P using the proposed approach fall within the interquartile range of measured data. The study also revealed that process configuration can affect: 1) how influent uncertainty is reflected in model predictions for effluent quality and cost related performances, and 2) the parameter rankings based on variance decomposition, particularly for effluent phosphate, sludge disposal and methane production. The results identified UCT and UCTM as more robust configurations for P removal (less propagated uncertainty and less sensitivity to N load) in the expense of incomplete denitrification. Moreover, based on the results of Monte-Carlo based scenario analysis, the balanced SRT for N and P removal is more sensitive to influent load variation/uncertainty for the A2O and JHB configurations. This gives a more operational flexibility to UCT and UCTM, where a narrow SRT range can ensure both N and P removal.

Treatment of heavy metals containing wastewater using biodegradable adsorbents: A review of mechanism and future trends

The direct disposal of industrial effluents into the aquatic system is considered as a significant environmental hazard in many countries. Because of poisonous chemicals, substantial volumes of effluent release, as well as the lack of adequate of conventional treatment methodologies, industrial effluent treatment is extremely difficult. Numerous researchers have been interested in adsorption technology for its high efficiency of pollutant removal, low cost, and abundantly available adsorbent. Various adsorbent materials, both natural and modified form, have been widely used for the removal of toxic contaminants from industrial effluent.This paper highlights recent advancements in multiple modification types to functionalize the adsorbent material, resulting in higher adsorption capacity on various toxic pollutants. This review provides an overview of the adsorption mechanism and parameters (pH, adsorbent dosage, initial concentration, temperature and interaction time), which influencing the removal efficiency of adsorbents. Furthermore, this review compiles the desorption study to recover the adsorbent and improve the cycle's financial viability. This review provides a concise overview of the future directions and outlook in the framework of adsorbent application for industrial wastewater treatment.

Fluoride ions sorption using functionalized magnetic metal oxides nanocomposites: a review.

Fluoride is an anionic pollutant found superfluous in surface or groundwater as a result of anthropogenic actions from improper disposal of industrial effluents. In drinking water, superfluous fluoride has been revealed to trigger severe health problems in humans. Hence, developing a comprehensive wastewater decontamination process for the effective management and preservation of water contaminated with fluoride is desirable, as clean water demand is anticipated to intensify considerably over the upcoming years. In this regard, there have been increased efforts by researchers to create novel magnetic metal oxide nanocomposites which are functionalized for the remediation of wastewater owing to their biocompatibility, cost-effectiveness, relative ease to recover and reuse, non-noxiousness, and ease to separate from solutions using a magnetic field. This review makes an all-inclusive effort to assess the effects of experimental factors on the sorption of fluoride employing magnetic metal oxide nanosorbents. The removal efficiency of fluoride ions onto magnetic metal oxides nanocomposites were largely influenced by the solution pH and ions co-existing with fluoride. Overall, it was noticed from the reviewed researches that the maximum sorption capacity using various metal oxides for fluoride sorption was in the order of aluminium oxides >cerium oxides > iron oxides > magnesium oxides> titanium oxides, and most sorption of fluoride ions was inhibited by the existence of phosphate trailed by sulphate. The mechanism of fluoride sorption onto various sorbents was due to ion exchange, electrostatic attraction, and complexation mechanism.

Ecosystem service approach for community-based management towards sustainable blue economy

The present study was undertaken to examine the role of community-based fishers in blue economy taking ecosystem and livelihood development and sustainability of Gulf of Mannar, Tamil Nadu, India. A questionnaire was designed to capture context-specific community-based blue economy practices. The virtual factors and environmental determinants which affect the sustainability of ecosystem between resource benefitters were evaluated. A significant difference is noticed between male and female beneficiaries for preference to all the variables except enhanced waste management practices variable (insignificant difference- 0.183; Mann-Whitney U test). All the variables significantly advance the livelihood sustainability of ecosystem-dependent population and the ecosystem service evaluation process. The present survey also resulted that the better sustainability of blue economy involved the significant implementation of growth agendas by minimizing the effluent and sewage disposal, developmental activities in industrial areas, disaster outbreak and eliminating harmful fishing practices, overfishing and instead incentivizing approaches that promote growth, improve conservation, build sustainable fisheries, and terminate the IUU (illegal, unreported and unregulated) fishing. An ecosystem-based management framework, improved governance is required to grow and improve the sustainability of livelihood and ecosystem towards a blue economy. Innovative financing to direct investments into economic activities is also needed to enhance ocean health. A further step would be to assess how such human inputs or improved management practices could be included in the set of ecosystem service indicators.

Toxicity effect of radiographic developer effluent on giant African snail (Achatina fulica)

Background: The decline in the population of snails, a source of protein of people living in the high forest zone due to environmental pollution and the hazard caused by the disposal of radiographic developer effluent into streams, bushes or forests and public sewer systems makes the assessment of the effect on giant African snails (Achatina fulica) from environmental pollution due to radiographic developer effluent very important.Materials and Methods: Ninety 5 months old, 12 months old and 24 months old giant African snails were randomly divided into 6 groups of 15 snails for each age group based on the dose of developer effluent to be administered. One group from each age group was designated the control and the remaining, the experimental group. Range finding test was performed at effluent concentrations of 100 %, 50 %, 25 %, 12.5 %, 6.25 %, 3.125 %, 1.6 % and 0 % (control) in 150 ml of distilled water. The effluent solution was administered on the feed and soil of the experimental snails only.Results: Behavioural changes occurred between 0.2 – 1.0 % concentration and mortality at 24 – 96 hours exposure to the effluent solutions. The percentage (%) mortality of the giant African snails increased as the effluent concentration increased from 0.2 - 1.0 % and at increased exposure time of 24 – 96 hours. The estimated 96 hours LD50 for the 5, 12 and 24 months old giant African snails were 0.20 0.23, 0.23 0.25 and 0.30 0.26 respectively.Conclusion: Radiographic developer effluent is harmful to the giant African snails, with the % mortality increasing with increase in concentration and exposure time to the developer effluent. Legislation is recommended to ensure safe disposal of radiographic developer effluents into the Nigerian environment considering the importance of giant African snails (Achatina fulica) to the ecosystem and the economy.

Assessment of trace metal content in water, soil and vegetables samples in the vicinity influenced by industrial effluents

Pollution of the environment by trace metals emanating from rapid economic growth and improper waste and effluent disposal is a major concern. In this study trace metal concentrations, Cu, Zn, Pn, Ni, Sn, Cr, Fe, Co Mn and Cd in water, soil and vegetable samples in two urban streams influenced by effluents disposal from two industries were analysed using PG-990 Model atomic absorption spectrophotometer. Analytical results of water samples in the vicinity of the two industries indicated higher concentrations of Cu, Zn, Pn, Ni and Mn above the acceptable limits reported by the FAO/WHO (2000). The concentration of trace metals in soil and vegetables from the two sites were within the tolerance limits reported by FAO/WHO (2004) and FAO/WHO (2007) respectively. Cd was not detected in water and vegetable samples from NASCO household industrial area and also in water samples from Grand Cereals and Oil Mills area. However, the higher concentrations of trace metals in the polluted (either directly or indirectly) areas were higher than the control indicator that industrial activities such as discharge of wastes and effluents into natural ecosystem in most cases without treatment may cause health hazard as well as environmental pollution.