Ecolab continued its buying spree this week with four small acquisitions that expand its pest-elimination and food-safety businesses.

The St. Paul maker of cleaning, sanitizing and filtration chemicals did not disclose the acquisition costs but said they were significant because they broaden Ecolab's services and geographic reach.

The company on Tuesday completed its purchase of Arpal Group, a Scottish cleaning- and sanitizing- products firm with locations in the United Kingdom and Middle East. Arpal generates about $20 million a year in revenue.

On Monday, Ecolab said it bought three U.S.-based pest-elimination companies that cater to food and beverage customers in specific parts of the country. Combined, they give Ecolab a broader footprint of pest-elimination services. Ecolab is already known for its products and services that help restaurants, hotels and hospitals.

"These acquisitions will complement our already strong offerings in the food and beverage markets," said Bobby Mendez, executive vice president and president of Ecolab's Global Services and Specialty business.

The companies, with a combined $36 million in annual sales, are: Food Protection Services, which operates in the Pacific Northwest, Great Lakes, Midwest and the Mississippi Delta; Delaware-based Royal Pest Solutions Inc., which operates on the East Coast; and Research Fumigation Company in Louisiana, which serves the South and Southeast.

Research Fumigation customizes services for companies storing, milling, processing or transporting bulk rice, corn, poultry and other food items. Its products and services cater to firms that import or export food on ships or that use barges, containers, grain bins, rail or truck trailers and other equipment.

The three firms each "bring a premium product and service approach similar to our own," Mendez said. "Through the addition of their expertise in food storage treatment, we can further strengthen our pest services offering to food and beverage customers — and play a bigger role in protecting the safety of food and our customers' operations across the food chain."

Ecolab, which generated $13.2 billion in 2016 revenue, has worked to diversify itself in recent years, most recently in ways that are not as volatile as its mega Nalco (2011) and Champion Technologies (2013) purchases.

Those two acquisitions thrust Ecolab into the oil and gas chemicals business for the first time, right before the oil and gas industry suffered a major downturn.

This year, the company announced it would buy the paper chemicals business of Georgia-Pacific for an undisclosed price and also bought the French disinfectant maker Laboratoires Anios.

In January, it bought the Michigan-based wastewater engineering firm Abednego Environmental Services, which specializes in water recycling, paint booth management and waste treatment services for auto manufacturers such as Ford Motor Co.

The acquisitions are assisting Ecolab's overall growth plans. The company is expected to disclose its 2017 revenue and profit information either in late January or early February.