September 2008, Vol. 20, No.9

A True Test of Sustainability 

The triumph of Incan civil engineering over scarce water resources survives today

A True Test of Sustainability Kenneth R. Wright
Inca water planning, management, and construction of water facilities were as varied as the Peruvian landscape. Decadelong field studies at the pre-Columbian archaeological sites of Machu Picchu, Moray, and Tipon have revealed that the Incas possessed an uncanny ability to develop water resources on a site-specific basis. This remarkable knowledge of water resources development principles occurred without a written language, use of the wheel, or the availability of iron or steel. Read full article (login required)


Sustainable Strategies To Manage Runoff

Successful implementation of green infrastructure projects

Sustainable Strategies To Manage Runoff James E. Scholl

Extreme weather patterns cause many significant water resource management problems. Intense rain events can result in flooding and pollution from sewer overflow events, while dry periods can cause water supply shortages and environmental damage resulting from dry rivers and low lake levels. The 2007 drought in the U.S. Southeast and the Midwest flooding this spring are recent examples of these extremes, which are a natural part of the hydrological cycle. However, recent trends in climate change indicate that these extremes may be increasing, and regional patterns will be difficult to understand and predict. Read full article (login required)


Better in Phases

Multiphase anaerobic digestion provides better solids treatment and increases biogas production

Better in Phases Zeynep Erdal and Tim Shea

A North Carolina wastewater treatment facility found that it had a problem. At a solids retention time of 20 days or longer, the facility’s single-phase mesophilic anaerobic digester produced biosolids with fecal coliform levels that initially met federal and state Class B requirements. After centrifuge dewatering and storage, however, fecal coliform levels rose, and the biosolids produced offensive odors, making the material unsuitable for land application.

Likewise, offensive biosolids odors at other facilities have eliminated some beneficial use options or caused public complaints. So, researchers evaluated anaerobic digestion technologies to find a solution. Read full article (login required)


Going Private for the Public Good

How the Town of Clarence, N.Y., benefited from a privately owned sanitary sewer interceptor

Going Private for the Public Good Joseph D. Latona

Many communities are facing a critical need to upgrade or install water or wastewater infrastructure — without adequate funding. The Town of Clarence, N.Y., faced such water pollution problems in high-density older residential areas with inadequate septic systems. The town also faced consent orders from the New York State Department of Environmental Conservation (DEC), along with the high replacement cost and lack of adequate space for septic systems.

The lack of funding and critical need for a solution were the catalysts for creative thinking and the development of several public–private partnerships between the town and housing developers. As a result, the town has developed a solution to its pollution problems in the older residential areas, as well as for undeveloped areas in the future. Read full article (login required)


Fueling the Flames 

Maximizing biogas use can improve the bottom line

Fueling the Flames David L. Parry

Today, power makes up about 25% of a wastewater treatment plant’s operating budget (second only to labor). When faced with the need to decrease energy costs, treatment plant managers have two options: demand-side and supply-side management. Demand-side management includes energy conservation and process improvements that reduce energy demands.Supply-side management involves the handling of energy resources, such as biogas. Producing more biogas and converting it into electricity, heat, or biomethane could fulfill most of a plant’s everyday demands.

Successful bioenergy systems balance economic, environmental, social, and operator objectives. Environmental objectives include beneficial use of biogas, “greener” operations, and lower emissions of carbon dioxide, carbon monoxide, methane, and nitrogen oxides (NOx). Social objectives include good public relations and appropriate aesthetic and acoustic standards. Operator objectives include reliability and ease of operation. Read full article (login required)


Rubbish to Reuse 

Bacteria in anaerobic digesters are even more efficient at processing food wastes than they are in treating wastewater solids 

Rubbish to Reuse Donald M.D. Gray (Gabb), Paul J. Suto, and Mark H. Chien

The U.S. Environmental Protection Agency (EPA) has recommended that 35% of the nation’s municipal solid waste be recycled by 2008. Many states have even higher solid waste diversion or recycling goals, and some major cities, such as New York, Oakland, San Francisco, and Seattle, have long-term “zero waste” goals (recycling 100% of municipal solid waste). To meet these goals, food-waste recycling will have to become more common. Unfortunately, such recycling is difficult because food waste must be processed quickly to avoid generating odors or attracting vectors, and food wastes from restaurants, grocery stores, and other food-handling facilities (post-consumer) can be highly contaminated, even when source-separated.

However, anaerobic digestion could recycle food wastes into renewable energy (methane) and fertilizer. A study conducted at the East Bay Municipal Utility District (EBMUD; Oakland, Calif.) showed that, with some pretreatment, food wastes could be processed in a wastewater treatment plant’s existing digesters. Read full article (login required)


Operations Forum Features

What? More Samples! 

Understanding the Importance of Proper Sampling 

What More Samples Margaret Doss
As wastewater treatment technologies advance, operators find themselves having to collect increasing numbers of samples throughout the plant. It is tempting to rush through sampling duties to get on with the business of operating the plant. What difference does it make when, where, and how all of these samples are collected?

The answer is that it could mean the difference between meeting permit limitations and receiving an enforcement action, such as a notice of violation, consent order, or monetary fine.

This article provides fundamental information on pertinent sampling issues. Topics include general sampling techniques, types of samples, bacteriological sampling, preservation methods, holding times, chain of custody, and safety. Read full article (login required)