L'usine de traitement des eaux usées industrielles de Mars (Chine) pour les aliments pour animaux de compagnie est achevée

Mars, Incorporated is an internationally renowned multinational fast-moving consumer goods company, producing and selling a variety of famous brands of chocolate, confectionery, and pet food worldwide. Mars Food (China) Co., Ltd. is Mars' wholly-owned subsidiary in China, owning numerous well-known domestic and international brands, including Dove chocolate, Snickers chocolate, M&M's chocolate, Skittles, Crunch (milk chocolate with crispy rice), Pedigree dog food, Whiskas cat food, and more. Mars 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 in the Chinese market include Pedigree dog food, Whiskas cat food, Sheba dog food, Cesar dog food, Temptations cat food, Iams dog food, and Nurture cat litter. Product categories include dry food, wet food (pouches and cans), treats, and care products, offering the most diverse and comprehensive range of pet care products in China today. This wastewater project concerns 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. During operation, issues such as inefficient scum removal in the grease trap, unstable UASB startup, and insignificant dissolved air flotation effects have been observed. There is a significant gap between the original process design and its current operation, rendering it unable to meet current operational requirements. Considering water reuse and the existing engineering conditions, we propose an upgrade and renovation of the process based on the original system to achieve water reuse standards. This plan covers the process design, equipment, electrical, automation upgrades, maintenance, and equipment commissioning for the entire wastewater treatment system, starting from the collection well.

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 biochemical treatment. As an international enterprise, Mars (China) has imposed multi-faceted requirements on our design and construction that exceed industry standards. They also require the treated wastewater quality to meet the standards stipulated in the People's Republic of China's "Water Quality Standard for Reclaimed Water Used in Landscape Environment" GB/T18921-2002 and "Standard for Reclaimed Water Used in Landscape Environment" GB/T18920-2002. The final treated water will be used for landscape water and greening throughout the entire factory area.

    设计处理废水水量为80t/d，设计进水水质为右图所示，北方冬天的低气温为生化处理的稳定性带来了很大难度，玛氏（中国）作为国际型企业，对我方设计施工提出高于同行业标准的多方面要求，并要求污水处理后水质标准达到中华人民共和国《城市污水再生利用景观环境用水水质》GB/T18921-2002和《城市污水再生利用景观环境用水水质标准》GB/T18920-2002的规定，最终处理水将用于整个厂区的景观用水及绿化。

Par des expériences et une série de démonstrations, diverses méthodes de traitement telles que la méthode anaérobie, la méthode aérobie et la méthode anaérobie-aérobie ont été utilisées pour le traitement des eaux usées de production alimentaire de ce projet. Ces méthodes ont réduit le CODcr et le BOD5 à des degrés divers, mais leur efficacité dans le traitement des huiles animales et végétales est médiocre. Compte tenu de la teneur élevée en huiles animales et végétales dans les eaux usées de production de cette entreprise, des mesures de prétraitement telles que la séparation des graisses et la flottation à air à haute efficacité sont adoptées pour éliminer la majeure partie des huiles animales et végétales des eaux usées avant le traitement biochimique aérobie. Grâce à la mise en service et à l'essai, le système de traitement des eaux usées fonctionne de manière stable et les eaux usées traitées ont atteint les exigences de la norme de rejet.