Module 8. Effluent treatment

Lesson 14

14.1 Introduction

The different types of solid waste include agricultural waste, paper waste, plastic waste, food waste, cloth waste, glass waste, building material waste etc.

14.2 Solid Waste

Solid organic waste in dairy processing facilities mainly originates from production processes and includes nonconforming products and product losses (e.g. milk spillages liquid whey and buttermilk), grid and filter residues, sludge from centrifugal separators and wastewater treatment, and packaging waste (e.g. discarded cuts, spent ripening bags, wax residues from cheese production) arising from incoming raw materials and production line damage.

Solid waste is generally

* off-spec product – for example, milk powders and heavy consistency product

* defective product packaging – for example, paperboard cartons, plastic containers

* recovered wastewater treatment sludges

* solid and semi-solid intermediate or finished product spills

14.3 Sources of Solid Waste in Dairy Processing Plants

The types of solid waste typically produced by dairy processors include packaging waste such as cardboard, paper, cartons and plastic; organic wastes such as sludge and reject product; and office waste. They can be generated during processing, or when raw materials and products are being transported, stored and handled.


Type of waste

Disposal stream


Cardboard boxes, paper, slip sheets


Plastic wrap


HDPE bottles and caps


Foil seals

Non recyclable

Liquid paperboard



Non recyclable

Plastic and metal drums and containers




Office waste (e.g. toner cartridges, paper)


Canteen waste (e.g. aluminum cans, polystyrene cups)


Miscellaneous (e.g. waste oil, oily rags,damaged pallets)



Reject product including in-process

Animal feed

Returned final product

Animal feed

Raw material (e.g. liquid flavours)

Re work

Obsolete or out-of-date raw materials

Animal feed

Lab samples and samples for online testing

Animal feed

Separator de-sludge

Animal feed

Bag house fines, dryer sweepings

Animal feed

Effluent sludge

Animal feed / compost

Membrane retentate sludge

Animal feed / compost

Cheese fines

Animal feed

Fat recovered from effluent

Animal feed

The cost of generating and disposing of solid waste can include

• treatment costs

• collection and transport costs

• disposal costs

• loss of product, including processing and raw material costs.

14.4 Solid Waste Management

Reducing the loss of materials and improving the rate of reuse, recovery and recycling of valuable resources is a very important aspect of eco-efficiency. The many economic, environmental and social incentives for reducing and utilising solid waste more efficiently include

* reduced treatment, collection and disposal costs

* reduced production costs as a result of recovering and reusing product

* increased revenue from recovering product

* increased revenue from new co-products

* improved risk management

* improved environmental responsibility

* improved resource utilisation.

14.4.1 Biomanagement of sludge

Biotechnology Resource Centre which is located at Pune, Maharastra has developed the technologies for management of sludge produced by different effluent treatment plants as well as city garbage and sewage. Wastes from aquaculture and animal husbandry are becoming increasingly severe for industries and municipalities due to waste disposal legislation. The Biomanagement of solid wastes include vermiculture technology, mushroom culture, growing algae on liquid effluents and aquaculture.

Last modified: Friday, 5 October 2012, 7:11 AM