Water as we all know is a crucial element for life and it cannot be wasted. Industrial wastewater treatment covers the mechanisms and processes used to treat wastewater that is produced as a by-product of industrial or commercial activities and produces a liquid effluent suitable for circulation into the process areas.
Need Of ETP:
Water is basic necessity of life used for many purposes, one of which is Industrial use. Industries generally pay heavy taxes for the raw water. But water once get used gets contaminated so it should be well treated so it can satisfy the proper prerequisites of usage in the plant. Thus an effluent treatment plant is always laid down in any industrial plant.
SOURCES OF INDUSTRIAL WASTEWATER :-
Agricultural / Food Industry
Wastewater generated from agricultural and food operations is biodegradable and non-toxic, but has high concentrations of biochemical oxygen demand (BOD) and suspended solids.
Vegetable washing generates waters with high loads of particulate matter and some dissolved organic matter.
Pulp And Paper Industry:
Effluent from the pulp and paper industry is generally high in suspended solids and BOD. Plants that bleach wood pulp for paper making may generate chloroform, dioxins, furans, phenols and chemical oxygen demand (COD).
Increased BOD or COD loadings, as well as organic pollutants, may require biological treatment such as activated sludge or up flow anaerobic sludge blanket reactors. For mills with high inorganic loadings like salt, tertiary treatments may be required, either general membrane treatments like ultrafiltration or reverse osmosis.
Waste waters can be contaminated by feedstock materials, by-products, product material in soluble or particulate form. Treatment facilities that do not need control of their effluent typically opt for a type of aerobic treatment, i.e. aerated lagoons.
The production of iron from its ores involves powerful reduction reactions in blast furnaces. Cooling waters are inevitably contaminated with products especially ammonia and cyanide.
Contamination of waste streams includes gasification products such as benzene, naphthalene, anthracene, cyanide, ammonia, phenols, cresols together with a range of polycyclic aromatic hydrocarbons.
Power plants are a major source of industrial wastewater. Many of these plants discharge wastewater with significant levels of metals such as lead, mercury, cadmium and chromium as well as arsenic, selenium and nitrogen compounds.
PROCESS FLOW DIAGRAM
The launder leads the dirty water from scrubber to the distribution chamber. Inlet channel is designed for a particular flow and velocity to avoid the distribution chamber.
The distribution chamber is designed to lead the water evenly to the flash mixers, downstream through channels by gravity. For equal distribution of flow to flash mixers isolation gates are also recommended.
This unit is provided for chemical reaction with effluent. Here effluent is treated with Alum as coagulant, Lime as pH regulator and Polyelectrolytes as Flocculent.
Stable Colloidal Suspension
Primary Coagulant (Organic/Minerals)
coagualtion Stage (Unstable Colloid, Micro Floc Formation)
Flocculation Stage (Large Flocs)
Setting Of Suspension
Clarifiers are settling tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and (or) thickening.
Main purpose of sludge tanks are to hold the underflow sludge and transfer it to filter press for dewatering.Each tank will be provided with mechanical agitator which will constantly agitate the sludge in order to prevent sludge settlement in the tank.
For dewatering purpose, filter press is most efficient and economical among all other filters. Other filtration systems offer high pressure filtration but only the filter press has both high pressure capability and efficient filter cake removal.