Measuring Industrial Waste Water Pollution: Methods And Management

Industrial wastewater is one of the most common by-products of industrial and commercial activities. It is the water that has been used in the production of commercial products across every industry in nearly all phases of production. Once used, it is considered waste and must be treated before it is discharged. The improper treatment and release of industrial wastewater causes irreversible damage to the ecosystem, contaminating water, air, and soil. To measure industrial wastewater pollution, three methods are commonly used: physical, chemical, and biological. These methods involve the collection of samples, followed by specialized analytical tests.

Characteristics and Values of Industrial Wastewater Pollution Measurement Methods

Measuring toxicity and mineralization

Industrial wastewater is a common byproduct of industrial and commercial activities. It is produced across every industry and in nearly all phases of production. Once used, this process water is considered waste and must be treated before it is discharged.

The measurement of industrial wastewater pollution involves assessing the levels of various contaminants and their potential toxic effects on human health and the environment. This includes testing for the presence of heavy metals, chemicals, oils, pesticides, pharmaceuticals, and other toxic substances.

The toxicity of industrial wastewater can be measured through various analytical techniques, such as mass spectrometry and pigment inhibition tests. These tests assess the impact of wastewater contaminants on aquatic life, such as microalgae, and help determine the potential risks to human health. For example, full-scan mass spectrometry and microalgae pigment inhibition tests were used to evaluate the toxicity of coking wastewater treated with in-situ electrogenerated chlorine dioxide. The results showed that the treatment process effectively reduced the toxicity of pollutants and inhibited the growth of specific microalgae species.

Another study utilized an enhanced electro-oxidation process to analyze the oxidation of phenol, cyanide, and aniline in wastewater. This process employed sodium chlorite as an electrolyte, and the results were validated using statistical tools. The mineralization efficiency for phenol and aniline was predicted to be 78.4% and 98.18%, respectively, at optimized variable conditions, while complete mineralization was observed for cyanide.

Mineralization processes aim to convert toxic or hazardous waste into less harmful or valuable products. For instance, the mineralization of alkaline waste through carbon capture, utilization, and storage (CCUS) technologies can produce carbonate and bicarbonate products with various industrial applications. These products can be used to create supplementary cementitious materials, geopolymers, and soil additives, reducing the need for carbon emission-intensive materials.

The utilization of mineralized products in place of emission-intensive materials has the potential to significantly decrease CO2 emissions. However, waste stream contamination and toxicity must be addressed before these mineralized products can be safely used. While mineralization stabilizes heavy metal-containing waste, materials containing toxic elements are not suitable for certain applications, such as building materials.

Overall, measuring toxicity and mineralization in industrial wastewater involves assessing the presence and concentration of toxic substances, evaluating their potential ecological and human health risks, and exploring treatment and mineralization processes to reduce their environmental impact.

Identifying pollutants

Industrial wastewater is a common byproduct of industrial and commercial activities, encompassing various sectors such as food and beverage, oil and gas, mining, chemicals, and pharmaceuticals. The identification of pollutants in industrial wastewater is crucial to mitigate its adverse environmental and health impacts. Here are some key considerations for identifying pollutants in industrial wastewater:

Physical Testing: Physical tests help assess the temperature and solid concentrations in the wastewater. Common parameters include turbidity and Total Suspended Solids (TSS). This provides insights into the presence of suspended solids, which are common pollutants in industrial wastewater.

Chemical Testing: Chemical testing involves examining water samples using analytical chemistry techniques. This method allows for the identification of various chemical pollutants, including metals (zinc, cadmium, copper, etc.), nutrients, pH levels, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and other specific contaminants like ammonia, chromium, phenols, and sulfides.

Biological Testing: Biological testing utilizes plant, animal, or microbial indicators to assess the health of the aquatic ecosystem. It helps identify the presence of toxic substances that may be harmful to aquatic life. For example, copepods and crustaceans can be used as indicators to determine the impact of pollutants on their survival and reproduction.

Sector-Specific Pollutants: Different industries generate distinct types of pollutants. For instance, the food industry's wastewater may contain organic contaminants, while the oil and gas industry's wastewater can include oil, grease, and suspended solids. Shale gas extraction produces wastewater with high concentrations of dissolved solids (salts), radionuclides, metals, and drilling chemicals. Understanding the specific pollutants associated with each industry is crucial for effective identification and treatment.

Hazardous and Non-Hazardous Waste: Industrial solid waste can be classified as hazardous or non-hazardous. Hazardous waste includes substances like dry cleaning fluids, embalming fluids, pesticides, and chemicals. These wastes can have severe environmental and health impacts and require special treatment to mitigate risks. Non-hazardous waste, on the other hand, does not meet the definition of hazardous waste and is typically managed separately.

Biodegradability: Identifying the biodegradability of pollutants is essential for effective treatment. While some compounds, like paper, leather, and wool, are biodegradable, others, such as heavy metals, pesticides, and plastics, are non-biodegradable. This distinction guides the selection of appropriate treatment methods to ensure effective pollutant removal.

Treatment methods

Industrial wastewater treatment methods are essential to promote sustainable water usage and address environmental and public health challenges. The treatment process can be categorised into four main methods and three primary stages. The choice of method depends on the type of wastewater and the degree of contamination.

The three primary stages of wastewater treatment are:

• Primary: This stage focuses on filtering coarse materials from the water, allowing finer particles to be removed in subsequent stages. The water is kept stagnant in a basin, causing solids to settle at the bottom by gravity, while substances lighter than water accumulate on the surface. After separating these substances, mechanical devices drain the still-polluted water into another basin for the next stage.
• Secondary: In this stage, the water undergoes progressively finer filtration methods to increase purity.
• Tertiary: This stage ensures the water is of high enough quality to be returned to industrial and domestic use. It includes one or more of the following steps:

• Filtration: The water is passed through a bed of sand or activated carbon, leaving behind particles that were previously suspended in the water.
• Lagooning: The water is stored in artificially created ponds and purified by plant growth and invertebrates that absorb particulate matter.

The four main treatment methods are:

• Chemical-Physical Splitting Plants: These plants separate different components of the wastewater through chemical and physical means. For instance, sedimentation and flotation are used to remove TSS (Total Suspended Solids) in wastewater from pulp and paper mills.
• Membrane Plants: Membrane filtration can be used to remove pollutants such as organics, ions, and AOX. However, this method is too costly if the contaminant load is mostly inorganic.
• Vacuum Distillation Systems: This method is unsuitable if the water contains latex, lacquer, paint, or protein.
• Advanced Oxidation Processes: This procedure is used to remove substances that are difficult to biodegrade, such as pesticides, pharmaceuticals, or biocides, with the help of ozone or hydrogen peroxide. It is often combined with UV light irradiation to degrade pollutants into stable, non-organic substances.

Other notable treatment methods include the BOD5 test, which measures organic pollutant loadings, and the COD test, which uses potassium dichromate to oxidise organic matter. Regulatory frameworks, technological innovation, and sustainability considerations are also critical for effective wastewater management.

Regulatory challenges

Measuring industrial wastewater pollution is critical due to its potential impact on the environment and public health. However, several regulatory challenges exist in this domain. Firstly, industrial processes often produce wastewater with high pollutant volumes, complex compositions, and unpredictable variability. This complexity necessitates a thorough analysis of the wastewater's physical and chemical characteristics to design an efficient and cost-effective treatment process. Keeping up with evolving environmental regulations and discharge limits can be challenging for companies, especially when stricter limits are imposed on certain pollutants, requiring costly upgrades to treatment systems.

Moreover, companies often struggle with limited resources and the need for stakeholder collaboration. They must navigate between meeting discharge standards and their own environmental, social, and governance (ESG) goals, such as net-zero emissions. While these goals demonstrate a commitment to sustainability, they may conflict with regulatory requirements. For instance, some technologies that reduce greenhouse gas emissions might be less effective at removing specific water pollutants. As a result, companies must carefully balance compliance with sustainability objectives.

Another challenge arises from the use of older equipment. Treatment systems that have reached the end of their lifespan may become less effective at pollutant removal, leading to compliance violations. Upgrading or replacing these older systems can be financially burdensome, especially for smaller businesses or long-standing companies with outdated technology. Furthermore, the regulatory landscape is constantly evolving, and companies must stay informed about these changes to ensure they have the necessary resources to maintain compliance.

Lastly, the measurement of industrial wastewater pollution faces challenges when it comes to data collection and accuracy. While local authorities collect real-time water quality data using advanced equipment, external factors like wind, precipitation, and river systems can influence the results. Self-reported data by firms on pollutant emissions offer an alternative source of information, but it is crucial to ensure that the data is precise and reflective of actual pollution levels to guide effective pollution mitigation strategies.

Advanced technologies

Reverse osmosis (RO) is a prime example of an advanced technology that goes beyond mere filtration. RO operates at a molecular level, eliminating dissolved salts, harmful chemicals, and microbes from wastewater. This process transforms contaminated water into a state resembling drinking water. Tertiary treatments, which follow RO, employ advanced filtration systems, ozone generation, and oxidation to target specific pollutants and achieve exceptional purity.

Biological treatments harness the power of nature, utilizing bacteria to break down pollutants in wastewater before it is reintroduced into rivers or reused on-site. Advanced oxidation processes, such as O3/H2O2/UV, Fenton oxidation, photocatalysis, and sonolysis, are highly effective in degrading refractory organic pollutants. These technologies offer advantages like non-selective oxidation, complete mineralization, and the absence of halogenated by-products.

In the realm of industrial wastewater management, nanotechnology and bioremediation emerge as promising advanced technologies. Nanotechnology offers precise and targeted solutions, while bioremediation leverages biological processes to remediate contaminated environments.

Additionally, the integration of hybrid energy solutions in wastewater treatment facilities optimizes costs and enhances sustainability. By adopting alternative energy approaches, such as green technology, we can reduce electricity consumption and associated emissions, as seen in the potential for switching to hybrid energy in US wastewater plants.

Frequently asked questions