This article is part of our Rising Stars Portfolio series.

My Rising Star portfolio is designed to generate both financial and social dividends. Unfortunately, the world isn't as clean and green as many of us would like. Despite our growing desire for a purer planet, we still tangle with garden-variety garbage, hazardous materials in need of proper disposal, and occasional major accidents.

Somebody's got to clean that up. That's where my latest purchase, Clean Harbors (NYSE: CLH), comes in.

The business
Clean Harbors provides environmental, energy, and industrial services focused on cleaning up messes (and avoiding them to begin with). The company says it's the largest hazardous-waste disposal provider in North America. Its more than 50 waste management facilities offer incineration, wastewater treatment, and landfill, recycling, and specialty disposal services.

Through 175 locations throughout North America, the company serves more than 50,000 customers, including small private entities, government agencies, and a majority of Fortune 500 companies. Clean Harbors also operates in countries such as the U.K., Sweden, and China.

Clean Harbors provides a dizzying array of services, many of which involve toting around garbage and recycling materials, as well as more mysterious services like "decoking" and "pigging." (These delightfully colorful terms refer to an environmentally friendly method for removing pipe deposits.)

Clean Harbors also performs spill clean-up operations; it helping to mop up the BP (NYSE: BP) oil spill in the Gulf of Mexico, and similar messes after Hurricane Katrina. Furthermore, rumors suggest that Japan may call upon Clean Harbors to help restore the country after its recent string of catastrophes.

The green…
Clean Harbors' business doesn't entirely revolve around high-profile environmental messes that require cleanup or remediation. Much of its recurring business relates to the disposal, recycling, incineration, and general handling of hazardous and non-hazardous waste products.

The company's business is a step in the right direction for a cleaner world. As Clean Harbors says in its Form 10-K, "Our first goal is to help our customers prevent the release of hazardous wastes into the environment." Clean Harbors recycles many materials, including "universal wastes" such as light bulbs, batteries, and mercury-containing thermostats. The company also destroyed more than 1 million pounds of chlorofluorocarbons (CFCs) in 2010.

In addition, Clean Harbors has begun greening up its own operations; it's boosting energy efficiency, buying greener supplies, and more frequently using railroads -- which emit less carbon per pound of freight than trucks -- for transportation. It's also looking into using renewable energy such as solar power to power some of its properties and systems.

… And the greenbacks
Mother Earth isn't the only stakeholder Clean Harbors seeks to serve. Smart acquisitions have powered the company's performance in recent years. It recently announced plans to purchase Canada's Badger Daylighting, whose innovative Hydrovac system performs excavation in a faster, safer, cleaner, more focused manner than traditional backhoe and digging techniques.

Clean Harbors' ability to cross-sell its services in different segments to existing customers lends it another competitive advantage. Its existing business ties to many major corporations and government agencies leave the company wide open for future growth.

Granted, Clean Harbors' stock has been on an upward run; shares have risen about 72% in the last 52 weeks. However, at a current PEG ratio of 1.29, the shares look reasonably priced for long-term stockholders.

And now, the risks
While its business model may look spotless, the company's emphasis on hazardous waste places it ankle-deep in risk. Although Clean Harbors touts its safety initiatives, it embarks on dirty, potentially dangerous jobs. If anything goes terribly wrong, Clean Harbors could be subject to legal, regulatory, and financial ramifications that could be rough on shareholder returns -- and seriously stain its reputation.

Furthermore, Clean Harbors operates in a highly competitive industry. Rival waste disposal players include Waste Management (NYSE: WM), Veolia Environmental Services (NYSE: VE), Perma-Fix Environmental Services (Nasdaq: PESI) , and tons of regional and private competitors. As all those companies duke it out to win contracts, driving prices for their services ever lower, Clean Harbors' earnings could suffer in the long run.

Expect volatility from this stock as well. The spotty nature of its work means that Clean Harbors may swing in and out of favor with investors, facing years of lumpy growth ahead. Cleaning up in the Gulf of Mexico last year boosted Clean Harbors' revenues and profile alike, but such major incidents could (and hopefully will) be the exception, rather than the rule. Rather than hoping for the company to score big off headline-grabbing emergencies, investors should patiently appreciate its more consistent recurring business lines.

My Foolish bottom line
Clean Harbors' emphasis on environmental services, coupled with its own internal sustainability efforts, ushered it into my
Rising Star portfolio. Until many industries clean up their acts, we're all better off with a company like Clean Harbors around to clean up the messes.

Add your thoughts on Clean Harbors in the comments box below, or add it to your watchlist.

This article is part of our Rising Star Portfolios series, where we give some of our most promising stock analysts cold, hard cash to manage on the Fool's behalf. We'd like you to track our performance and benefit from these real-money, real-time free stock picks. See all of our Rising Star analysts (and their portfolios).