ETP for Rice MillRice Mill Effluent Treatment Plant

To put it simply, rice mill effluent has an adverse effect on the natural environment hence installation of effluent treatment plants for rice mill is imperative for the sustainable growth of the sector and to protect the environment from degradation, becoming greener is important.

In recent years, considerable attention has been paid to the industrial wastes which are usually released into different watercourses.

Increasing environmental awareness has triggered various rice mill industries to install or set up appropriate wastewater treatment technologies. As the number of rice mill grows, the need for adequate wastewater management has become very much essential.

1. Rice Mill Effluent Treatment Plant, Why is One Needed?

As you may be well aware a huge number of rice mills are engaged in rice milling which is the process of removing the husk from paddy to produce edible rice for the food industry.

The water is mainly used to soak the rice. In the rice mill, huge volumes of wastewater and other by-products are released when processing the paddy rice. The rice mill effluent coming from various rice mill operations often contain a high concentration of toxic organic and inorganic matter which causes significant environmental damage when released, one of these known by-products is Cyanide.

Rice mills – one of the major agro-industries are recommended to take action to reduce the volume and strength of the effluent. Because rice mills are considered as one of the most polluting sectors among other industries both in terms of the amount of discharge and wastewater or effluent composition, this shows the importance to why we need cleaner effluent at the end of the processing line.

Water is most important factor required during the pre-processing of rice and after boiling; the wastewater is also produced which also requires necessary treatment. The treatment of the rice mill effluent is highly essential to render the effluent suitable for discharge into surface water. Effluent treatment plants for rice mills is of the utmost importance as they strive to meet stringent discharge conditions, and reduce operating costs.

The prime environmental hazard of the rice mill effluents is their foul smell and it also consists of numerous hazardous pollutants at various process stages like pre-cleaning, de-husking, polishing, mist polishing etc. So the setting up of an effluent treatment plant for rice mills should be a prerequisite.

2. Physico-chemical characteristics of rice mill effluent:

The rice mill effluents carry a high load of suspended and dissolved organic matters causing serious environmental pollution. Contaminants present in the rice mill effluent exceeded the effluent discharge standards and contain the traces of pesticide overuse.

Among agro-industries, rice processing industry (rice mills) require the constant need of water in the processing of rice and which in turn results in the generation of huge amounts of wastewater.

Effluent characteristics of a rice mill vary depending on the type of rice being processed. Majorly it consists of contaminants like PH, total solids, dissolved solids, TSS, COD, BOD etc.

The dangerous effect from all these contaminants can be greatly reduced by using ETP for rice mill.

3. Treatment processes involved in ETP or Effluent Treatment Plant for Rice Mills:

Treatment of effluent from rice mills using ETP will greatly control environmental pollution. Here, you will get to know the sequence of treatment processes involved in ETP for rice mills:

  1. Preliminary or pretreatment of rice mill effluent:

This treatment is required to remove large solid materials that could cause damage and clogging of plant equipment. Large floating objects present in rice mill wastewater/effluent can be easily removed by passing wastewater through bar screens. After the removal of large solid materials, partially treated wastewater is subjected to next treatment level called primary treatment.

The advantage as you can see is that this will protect your equipment from damage caused by large particles, stones and debris.

  1. Primary treatment of rice mill effluent:

When pretreated wastewater enters into the primary treatment tank, removes about 60-70% of solid materials by physical or physicochemical processes and 40% of BOD. This treatment involves grit chamber to remove grit and also removes oil and grease by floatation method. It uses primary clarifiers where solid waste called sludge settles to the bottom which can be removed and treated in later stages. The primary treated water will then enter into the aeration tank for biological treatment.

  1. Secondary treatment of rice mill effluent:

The main objective of this treatment level is to remove BOD present in rice mill effluent. Most ETPs use the widely known aerobic process (activated sludge process) in which liquid wastewater enters into aeration tank where wastewater mixes with air to encourage the growth of microbes and hence the breakdown of organic matter takes place. When aerated water enters into the secondary clarifier where heavier particles settle to the bottom which is called as secondary effluent. It removes about 70-80% of organic solids.

  1. Tertiary treatment of rice mill effluent:

Liquid wastewater collected in secondary clarifier is now pumped to the tertiary treatment which removes any residual suspended solids which were not removed in earlier levels. It involves disinfection process to reduce the spread of waterborne diseases and also to minimize public health problems by removing leftover pathogenic organisms in wastewater/effluent. It uses some disinfectants like chlorination, UV light, ozone etc.