Abstract
The removal of heavy metals from our environment especially industrial effluents is now shifting from the use of conventional adsorbents to the use of chemical precipitation. The presence of heavy metals in the environment is a major concern because of their toxicity, bioaccumulating tendency, and threat to human life and the environment. The main objective of this research is to study the effectiveness of the combination of hydrogen peroxide and activated bentonite clay in the removal of heavy metal ions from pharmaceutical industrial effluent. About 13.790 mg/l of Fe, 1.650 mg/l of Zn and 2.000 mg/l of Ni were detected in the digested sample and batch removal of heavy metals such as Fe, Zn and Ni from industrial wastewater effluent under different experimental conditions using hydrogen peroxide as precipitating agent in combination with activated bentonite clay as adsorbent. Appreciable differences in the level of heavy metals concentration were observed based on pH effect. The result shows higher effectiveness relatives to other treatments formulated for the effluent treatment such as Alum precipitation effect, effect of hydrogen peroxide concentration dose, contact time effect and temperature effect. Removal of heavy metals in effluent was optimum at pH 10 for zinc (Zn) and nickel (Ni) and at pH 8 for iron (Fe), at temperature of 50°C, 0.75% hydrogen peroxide concentration dose and 100 mins holding time, reducing the amounts from 13.790 to 1.436 mg/l of Fe, while 1.650 to 0.127 mg/l of Zn and 2.000 to 0.115 mg/l of Ni respectively. The percentage differences in concentration for the heavy metals removal in industrial wastewater are as follows: Fe (89.58%), Zn (92.30%) and Ni (94.22%). The result showed high level of Zn and Ni generated from this pharmaceutical industry is above 1 mg/l FEPA and WHO standard but only Fe showed low level concentration compared to 20 mg/l FEPA and WHO standard in this study. This study reveals the need for enforcing adequate effluent treatment methods before their discharge to surface water to reduce their potential environmental hazards.
Highlights
Environmental protection and rational use of natural resources and other industrial raw materials has become a very important sphere of mankind’s advancement in the 20th century
Sample treatment was carried out using Alum solution for clarification while hydrogen peroxide and activated bentonite clay were used as treatment reagent
Analysis of the treatment and the results shows that when the concentration of hydrogen peroxide dose was increased from 0.75 - 1.25ml, there is decrease in the percentage removal of the three heavy metals present in the effluent due to the availability of different side reaction, Reduction of free Fe2+, Zn2+, Ni2+ ions, this condition results to the decrease in percentage removal of the three heavy metals present in the effluent which later result to more of hydroxyl ion (OH-) in solution reacting with excess hydroxyl ion(OH-) from the decomposition of hydrogen peroxide and form hydrogen peroxide in the solution
Summary
Environmental protection and rational use of natural resources and other industrial raw materials has become a very important sphere of mankind’s advancement in the 20th century. Mankind’s demand for resources and raw materials has increased the ecological and economic contradictions in the industries (Sen and Chakrabaty., 2009). This wide spread industrialization in urban areas has drastically reduced land area for waste disposal. Disposal of untreated industrial and domestic wastes into the environment affects both soil and ground water quality. The industrial effluents consist of organic compounds along with inorganic complexes and other non-biodegradable substances. These pollutants alter the quality of ground water and soil and pose serious problems threats to public health and/or affect the aesthetic quality of potable water. According to World Health Organization (WHO), the metals of most immediate concern are chromium, zinc, iron, mercury and lead (WHO, 2010) and Maximum allowed limits for contaminants in “treated” wastewater are enforced in developed and many developing
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