Anaerobic Treatment of Milk Processing Wastewater

Abstract

Anaerobic processes are widely used for the treatment of milk and dairy effluents. This technology has been subjected to significant development and real-scale application in the last few decades and offers highly favorable perspectives to accomplish a complete biodegradation of the components present in milk processing wastewaters such as sugars, proteins, and fats. Nowadays, anaerobic systems for the treatment of milk wastes can be operated successfully constituting an important contribution for the preservation of environmental quality.

Dairy Wastewaters – General Characteristics and Treatment Possibilities – A Review

“…The amount and characteristics of the wastewater depend largely on the factory size, applied technology, eff ectiveness and complexity of clean-in-place (CIP) methods, good manufacture practices (GMP), etc. (3,4). However, the introduction of GMP can reduce the world's wastewater mean volume from 0.5-37 to 0.5-2 m 3 of effl uent per m 3 of processed milk (3,19).…”

“…A major factor in the volumetric loading of dairy wastewater treatment plants are the immediate discharges produced in the cleaning of tank trucks, pipelines or equipment at the end of each cycle. In such cases, the effl uent volumes are higher than those of manufactured milk (4,21). On average, wastewater discharge is 70 % of the amount of the fresh water used at the plant (6).…”

“…COD=chemical oxygen demand, BOD u =ultimate biological oxygen demand (1, [3][4][5][6][7]9,11,13,14,17,18,20,22,23,35) Milk reception …”

“…The dairy industry includes the transformation of raw milk into pasteurised and sour milk, yoghurt, hard, soft and cott age cheese, cream and butt er products, ice cream, milk and whey powders, lactose, condensed milk, as well as various types of desserts (1)(2)(3)(4)(5)(6). The general distinctions among these foods are due to the reuse of non--fat milk and whey (a by-product in cheese manufacturing) and the evaporation of the free water from the coagulum as well as from milk and whey powders (5).…”

“…Moreover, in around 50 % of the world's whey production, especially concerning acid whey, it is untreated prior to disposal (8)(9)(10). The effl uents originating from various production technologies are not discharged simultaneously, thus forming a stream with wide qualitative and quantitative variations (4). Notwithstanding the diff erences in composition, att ributable to the manufactured product and technological operations (11,12), dairy effl uents are distinguished by their relatively increased temperature, high organic content (13)(14)(15) and a wide pH range, which requires special purifi cation in order to eliminate or reduce environmental damage (1).…”