In the past few years, mankind has been manipulating the natural environment to better suits its needs for providing infrastructure for residential, commercial, business and industrial purposes. Therefore, managing environmental risks has been recognized as an important and very useful process to achieve safety and environmental sustainability. Most of the countries practice the water quality index (WQI) method, which is similar to the existing department of environment (DOE) index. The WQI is an important tool to determine the quality of water. In the present study, water samples were collected from the seven various industry such as liquor industry, cement industry, chemical industry, power plant, oil refinery, steel plant and construction industry during the year 2019 and 2020. The six water quality parameters have been considered for the calculation of water quality index viz. pH, Total suspended solid (TSS), Chemical oxygen demand (COD), Biochemical oxygen demand (BOD), Oil and grease (O &G), Iron (Fe). The present study is helpful in proper planning and management of available water resource for natural purpose.
For proper identification and classification of the water and for deriving adequate information regarding its relevant physical, chemical and organic properties at the site under investigation, the following laboratory tests were conducted on the water samples collected from the different industries for the year 2019 and 2020:
- Determination of pH of the water: pH is a scale used to specify the acidity or basicity of an aqueous solution.
- Determination of Total suspended solids (TSS): TSS refers to the particles in the water that are larger 0.45 µm.
- Estimation of Chemical oxygen demand (COD) in the water: The COD is the amount of oxygen consumed to chemically oxidize organic water contaminants to inorganic end products.
- Estimation of Biochemical oxygen demand (BOD): Commonly used parameter for determining the oxygen demand on water.
- Determination of Oil and grease (O&G) in the water.
6. Determination of Iron (Fe) in the water.
RESULTS AND DISCUSSION
According to U.S.EPA, the pH safety range of the water is around 6.5 to 9.5. We observed that for liquor industry and chemical industry it goes bellow to the safety range in February, March, April, May and August, respectively as shown in [fig 1(a)].
Chemical industry has higher pH value in September month in 2020 [fig 1(b)]. We also noticed that construction industry has low pH value in June in 2020 [fig 1(b)]. Fluctuating pH or sustained pH outside the safety range produce significant effect on the aquatic and human life such as physiologically stresses many species, increase mortality rate and decrease the reproduction rate. The pH of water may be Acidic due to the use of weak organic acids i.e., acetic acid, tannic acid or strong mineral acids, common source of acidity is the carbon dioxide as carbonic acid. Alkalinity can be caused by carbonates, bicarbonates, hydroxides, borates, silicates, phosphates etc.
Additionally, TSS is the important parameter to measure the particle size more than 0.45 µm, particularly in natural water contain a large variety of material that could include clays, silts, inorganic and organic matters which does not dissolve in water and produce a large particle sizes and optical characteristic. We noticed that construction, power plant, cement industry and chemical industry has higher TSS value in their water sample some times in 2019 [fig 1(c)]. Similarly, in 2020, cement industry, oil refinery, liquor industry, construction and steel plant have higher TSS value shown in [fig 1(d)]. The higher TSS value may case the reduction of growth rate of aquatic life, increase water temperature, decrease dissolved oxygen level.
The COD and BOD are the important indicator to measure the oxygen level in the water. COD of the surface water are normally range from 5 to 20 mg/l.
We observed that COD is considerably high for liquor industry, cement industry, chemical industry, construction and oil refinery in 2019 [fig 2(a)]. Similarly, as shown in [fig 2(b)], the higher COD value is identified for liquor industry, cement industry, oil refinery and steel plant. Higher COD value indicates serious pollution or organic matter in the water. Like COD, we also noticed higher BOD values for liquor, cement, oil refinery, construction and chemical industry in 2019 as shown in [fig 2(c)]. Liquor, cement and oil refinery also has high BOD of water in 2020 [fig 2(d)]. Normally safe amount for BOD ranges: 1 mg/L – Pristine water, 2-8 mg/L – Moderately polluted water, 20-30 mg/L -Municipal, industrial sewage. The consequences of higher BOD are the same as those of low dissolved oxygen as a result aquatic organisms become stressed, suffocate and die. Higher COD value may be due to the presence of interfering agents like NH4+, NO3-, Cl-, in the sample. These got oxidized by K2Cr2O7 in strongly acidic medium (H2SO4) and hence an alteration comes in COD values. Using complex organic chemicals can generate waste water contaminated by COD, organic chemicals, heavy metals, suspended solids etc. which makes a BOD value higher.
Besides, oil in the water also effects the lives of the aquatic beings by inhibiting the atmospheric oxygen in the water. We noticed that liquor, cement and oil industry produce high oil and grease in the water in the year of 2019 and 2020 as shown in [fig 3(a) and 3(b)]. The high value of O&G causes ecology damages for aquatic organisms, plants, animals, and equally mutagenic and carcinogenic for human being.
On the other hand, we also found that power plant, construction and oil refinery produce larger iron than the safety range (<0.3 mg/L) in 2019 and 2020 [fig 3(c) and 3(d)]. Although Iron in water is not directly hazardous to one’s health, but high iron levels can cause several damages like- Staining, Metallic taste and smell, altered appearance of food, Bacterial overgrow.
Our measurements reveals that Cement industry, Oil Refinery and Liquor Industry may produce some adverse effects on the environment. Cement Industry has low pH, high TSS, COD and BOD values. It was also observed that the high value of these parameters sustains in the winter season. Liquor industry also has low pH, high COD and BOD, constantly increases in summer and winter. We found the effect of Oil Refinery is not so good on our environmental ecosystem as described which sustained all over the year. The other industry i.e., Power Plant, Construction, Chemical Industry and Steel Plant do not produce any serious effects than the former do.
Industrial pollution continues to cause significant damage to the earth and all of its inhabitants due to chemical wastes, waste waters, others toxic materials etc. It affects ecosystem and disrupts natural habitats. Industrial damages can also be managed by this suitable method such as Segregation and Recycling, Use of Landfills, Composting.
Contributed By: Moumita Roy