Mars (China) Pet Food Industrial Wastewater Treatment Plant has been completed

Mars, Incorporated is an internationally renowned multinational fast-moving consumer goods company that produces and sells a variety of famous brands of chocolate, confectionery, and pet food worldwide. Mars Food (China) Co., Ltd. is a wholly-owned enterprise of Mars, Incorporated in China, with numerous well-known domestic and international brands under its umbrella, including Dove chocolate, Snickers chocolate, M&M's chocolate, Skittles, Crunch (crispy rice milk chocolate), Pedigree dog food, and Whiskas cat food. Mars, Incorporated began producing pet food in 1935 and was the first company in the world to produce professional pet food. It entered China in 1993, becoming one of the earliest pet food manufacturers in the Chinese market. In 1995, Mars China invested in and established its first pet food factory in Huairou. Currently, the pet care product brands sold by Mars, Incorporated in the national market include Pedigree dog food, Whiskas cat food, Cesar dog food, Eukanuba dog food, Temptations cat food, Iams dog food, and Sheba cat litter. Product categories include dry food, wet food (pouch and canned), treats, and care products, offering the most comprehensive and diverse range of pet care products in terms of categories and varieties currently available in China. This wastewater project pertains to the food processing wastewater from the Mars Petcare factory in Huairou.

The existing wastewater treatment station at Mars Food currently employs a pretreatment + anaerobic + aerobic process design. During operation, issues such as inefficient skimming of scum in the grease trap, unstable startup of the UASB, and insignificant effectiveness of the dissolved air flotation process have been encountered. There is a significant gap between the original process design and its current operation, which can no longer meet the current operational requirements. Considering reclaimed water reuse and the existing engineering conditions, we recommend upgrading and renovating the process based on the existing foundation to meet the requirements for reclaimed water reuse. This plan starts from the collection well and includes the process design, equipment, electrical, and automation-related upgrades, maintenance, and equipment commissioning for the entire wastewater treatment system.

The designed wastewater treatment capacity is 80 tons/day, with the designed influent water quality as shown in the right figure. The low temperatures in Northern China during winter pose significant challenges to the stability of biological treatment. As an international enterprise, Mars (China) has put forward multi-faceted requirements that exceed industry standards for our design and construction, and requires the treated wastewater quality to meet the standards stipulated in the "Water Quality Standard for Reclaimed Water in Landscape Environment" GB/T18921-2002 and the "Water Quality Standard for Reclaimed Water in Landscape Environment" GB/T18920-2002 of the People's Republic of China. The final treated water will be used for landscape water and greening throughout the entire plant area.

Through experiments and a series of arguments, various treatment methods such as anaerobic, aerobic, and anaerobic-aerobic methods are used for the food production wastewater treatment of this project. These methods have different degrees of reduction for CODcr and BOD5, but the treatment effect on animal and vegetable oils is not good. In view of the actual situation of high content of animal and vegetable oils in the production wastewater of this enterprise, pretreatment measures such as oil separation and high-efficiency air flotation are adopted to remove most of the animal and vegetable oils in the wastewater before aerobic biochemical treatment. Through debugging and trial operation, the wastewater treatment system operates stably, and the treated wastewater meets the requirements of the discharge standard.