Lean Water 101

Lean water is contaminated with organic pollutants. Organic compounds like solvents, herbicides, pesticides, PCBs, heterocyclic, aliphatic, and aromatic hydrocarbons are included in lean water from agricultural and industrial production.


The lean water discharged by many industries contains complex organic pollutants with a high concentration of biochemical oxygen demand (BOD) and suspended solids (SS). Municipal sewage contains different kinds of organic pollutants like dissolved organics, food, oil, and some surfactants. All of these organic pollutants in water can harm the environment and pose health risks for humans.

Common poisonous substance in lean water

The organic pollutants in lean water can be divided into two groups according to their biological degradation abilities. First, the organic contaminants with good hydrophilicity and accessible structures are quickly degraded in the environment.


Algae, fungus, and bacteria could degrade these organic pollutants like methanol polysaccharides. However, some of them, such as methanol and acetone, could result in acute toxicity when they exist in lean water at a high concentration. While on the other hand, persistent organic pollutants like DDT, PCBs, and PAHs, are degraded or slowly metabolized.


Here are the most common poisonous substances in lean water:

  • Solvents (Hydrocarbons)
  • Chlorinated compounds
  • Phenol
  • Benzene
  • PCBs
  • Organophosphorus pesticides
  • Amines

Environmental hazards of lean water

High amounts of hydrophilic organic pollutants like oil and organic matter could consume a large amount of soluble oxygen. The increased quantity and acute toxicity of oxygen demand could worsen water quality, leading to significant damage to the aquatic ecological system. However, the negative influence on the environment doesn’t always last long since wild microorganisms can sometimes quickly degrade them. A similar accelerated process takes place in bioreactors, which mitigate pollution.


In the case of persistent organic pollutants (POPs), the situation is a bit different. They have less water solubility, high accumulation capacity, and potentially carcinogenic, neurotoxic, and teratogenic properties. Many of the organochlorine pesticides cited above are neurotoxic, teratogenic, and carcinogenic. The benzofurans and dioxins are highly toxic and are quite persistent in the human body and the environment. Many POP, including DDT and its metabolites, dioxins, PCBs, and some chlorobenzene can be detected in the serum and human body fat after any known exposure.

Standard tests to determine organic pollution in lean water

Lean water treatment facilities rely on biological processes to break down a wide variety of organics. They use these processes to convert sewage and lean water into effluent and safely return the product to the water cycle with minimal impact on the environment. To ensure these processes’ efficiency and safety success, it’s crucial to monitor the chemical measurements of specific parameters.


The specific values and tests can vary by location but the three common measurements in the industry are Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), and Biochemical Oxygen Demand (BOD). We explain each below:


Total Organic Carbon is helpful as a non-specific indicator of water quality. The ubiquitous nature of carbon provides a screening tool to determine the water quality status.


Chemical Oxygen Demand is another test that is useful to measure water quality in lean water treatment facilities. In COD, testing a known amount of solid oxidizing agents under acidic conditions is helpful to convert all the organic species into CO2.


Biochemical Oxygen Demand is a procedure to determine the amount of dissolved oxygen used by microorganisms in a given sample. The aerobic biological organism in water requires oxygen to break down the organic material. The biological oxygen demand is affected by the same factor dissolved in the oxygen, such as pH and temperature. Therefore, measurement of the biochemical oxygen demand required two measures.

The treatment process of different industrial lean water

Here are some of the industries which produce lean water and other methods of lean water treatment for various industries:

Coking plant

Coke produced by the pyrolysis of natural coals is indispensable for most metallurgical facilities. During the coking process, coal decomposes into the organic compounds of solid, liquid, and gases. The handling of the coke lean water usually consists of a series of physic-chemical treatments that reduce solids, cyanide, ammonia, and other substances.

Textile lean water

Pigments and dyes have been utilized for coloring in the textile industry for many years. As a result, many types of textile dyes are available with various textile materials. Among the different technologies applicable for the treatment of textile lean waters, Activated Sludge Process (ASP) and Coagulation-Flocculation (CF). It has wide use and is simple to operate and efficient.

Fermentation and food lean water

Food fermentation and processing industries have been experiencing significant growth. As a result, lean water streams discharged from these industries are usually characterized by high-strength nutrient and organic contents. The conventional treatment of this high-strength lean water is aerobic/anaerobic activated sludge processes.

Pharmaceutical lean water

The pharmaceutical manufacturing industry produces a vast range of products useful as animal and human medications. The treatment of pharmaceutical lean water is challenging to reach the desired effluent standards due to the wide variety of products produced in a drug manufacturing plant. The pharmaceutical lean water requires advanced oxidation methods.

Sugar refinery lean water

Sugar refineries generate a high-colored effluent that comes from regenerating anion-exchange resins. However, the effluent represents an environmental problem due to the high organic load, phenolic compounds, and intense coloration.

Petrochemical production lean water

From polymers to paints to resins, the production of petrochemical-based products and intermediates represent a large portion of lean water produced. This waste oftentimes contains both dissolved and phase-separated organics with water and is most always hazardous waste.

How CWE treats industrial lean water

At CWE, our industrial lean water processing plants use various thermal technologies and biological treatments. CWE offers high-end lean water processing that includes neutralization, filtration, extraction, separation, and recycling of lean water streams, prior to discharge. CWE’s facilities for lean water management deliver environmentally friendly lean water treatment returning water safely to the environment. We use tried-and-tested processes and cutting-edge systems to generate effluent that meets regulatory compliance and helps protect the environment.

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