May-June 2000

The topics in this newsletter are considered to be timely and of interest. Comments and suggestions are invited. The use of trade names in this newsletter is not an endorsement of any company or product by the Maryland Cooperative Extension, University of Maryland, College Park.
David S. Ross, Extension Agricultural Engineer

Why do we need to concern ourselves with the amount of organic matter that is present in wastewater?

It is important to know what the organic matter content of a waste stream is because it influences the selection of a suitable method of wastewater treatment and disposal. Other important wastewater characteristics that must be considered when selecting a treatment method include the rate of production and the levels of solids and nutrients such as nitrogen and phosphorus.

Example: A food processor is exploring sprinkler irrigation as a potential method for treating and disposing of the processing wastewater because several sites with appropriate soil characteristics are available for irrigation.

However, if some wastewater components are present at high levels, irrigation may not be possible. For example, excessive suspended solids in the waste may clog irrigation equipment and soils. High levels of salts can also sometimes be a problem, although normal rainfall in the Mid-Atlantic region is generally sufficient to leach salt out of the soil. Nutrient management plans, which are required by the Water Quality Improvement Act of 1998, may also limit application on the basis of the nitrogen and phosphorus content of the wastewater. Finally, consideration must be given to the organic matter content of the wastewater because high loadings of organic matter can cause excessive build-up of soil microorganisms that grow on the applied organic material. This can cause a microbial slime layer to form on the soil surface, which can lead to soil surface clogging, and in turn, surface ponding, unpleasant odors, and vegetation decay.

Because organic matter can play such an important role in determining the success or failure of wastewater treatment methods, permits from the Maryland Department of the Environment for land application or surface discharge of processing wastewater define limits for the amount of organic matter that can be applied. These permits also define nutrient and other parameter limits, as well as hydraulic loading rates and application schedules.

What is actually measured when we quantify the organic matter in wastewater?

Frequently, we do not need to know the concentrations of individual organic compounds present in wastewater. Instead, it is often sufficient to have a combined measure of the mixtures of organic compounds found in wastewater. Two of the most commonly used measures of the combined organic content of wastewater are expressed in terms of oxygen demand. These two measures are called the biochemical oxygen demand (BOD) and the chemical oxygen demand (COD). At first, use of the term "oxygen demand" to report organic matter content may seem confusing. This convention is used because most organic compounds in water undergo oxidation reactions, and if dissolved oxygen is present, these reactions consume, or demand, oxygen. For example, the oxidation of organic matter can be carried out by microorganisms, that is, it occurs through biochemical reactions. In the presence of dissolved oxygen, the biochemical oxidation of organic matter is carried out by aerobic microorganisms according to the following generalized reaction:

Organic matter + oxygen + nutrients + cells
carbon dioxide + water + ammonia + new cells

The amount of oxygen needed to react with the organic matter in the above equation is equal to the biochemical oxygen demand of the organic matter and is measured in the BOD test.

The oxidation of organic matter can also occur through strictly chemical reactions. The amount of oxygen that reacts with the organic matter in the strictly chemical reactions is not measured using the BOD test. Instead, it is measured using the COD test, which does not involve microorganisms. The BOD and COD tests are similar in that they both measure the amount of organic matter present in a wastewater indirectly, by quantifying the amount of oxygen that is used up in biochemical or chemical reactions.

In the next installment, the procedures used to carry out the BOD and COD tests will be described.

Jennifer G. Becker, Extension Engineer

Automobiles are more complex under the hood than when most parents learned to drive. New drivers are less likely to have grown up under the supervision of someone who works around motorized equipment and engines. How are these new drivers going to learn to maintain their automobiles? Few among today's parents have much understanding of what goes on under the car's hood. The basic maintenance procedures save the owner from expensive repairs.

One of the first things the new driver should do is read the operator's manual for the vehicle to gain an understanding of maintenance requirements. The manufacturer specifies certain maintenance procedures that are to be done at regular intervals. Sometimes a chart is given to outline the service procedures by mileage intervals or by monthly or annual time periods.

A second thing is to maintain a record in a small spiral notebook that fits into the glove box or center console of the vehicle. Record each gasoline purchase by using columns for the date, vehicle mileage, gallons of gasoline or diesel fuel, and the cost. This creates a regular use for the notebook and allows the miles per gallon of fuel use to be calculated. Perhaps more important for the purpose of this article, all service and maintenance work on the car should be recorded. Record the date, mileage, and service work done. Important items include oil and filter changes, lubrication, air filter changes, tire rotation and balancing, radiator coolant changes, brake inspections and service, and more. These are services for which records should be handy so the next time for service can be determined quickly. A note can be made in the top margin of the page on when the next service is due, either in terms of mileage or by date.

A third thing is to establish a regular routine of checking certain items on the car regularly. Make a list of items and post it in the garage or in the record notebook described before. The chart can include items to check weekly, monthly, and annually. The amount of mileage put on the vehicle monthly and the condition of the vehicle will help to determine the reasonable frequency for these services.

On a weekly or biweekly basis the following items are suggested to be part of the vehicle service checklist:

 

1. Check oil level and condition. To check the oil, park the vehicle on a level surface and turn OFF the engine. Find the engine oil dipstick under the hood. Remove the dipstick, wipe it off, look at the markings for oil level, and replace the dipstick. A "full" level and an "add" level should be marked on the dipstick. Remove the dipstick again and observe the oil level. Add oil, if necessary, but usually only if a full quart is required. Do not over fill. If the oil looks very dirty, check on the time for changing oil.

    

2. Radiator Fluid. Check the level of the radiator fluid in the expansion tank. The high hot level and the low cold level are usually marked on the side of the reservoir. The level will be higher when the engine is hot. When the engine cools, some of the fluid is drawn back into the radiator. This is a good time to check to see that the minimum (cold) level of fluid is present. Do not overfill. Add a 50-50 mix of water and antifreeze to the expansion tank if the fluid level is low. Do not remove the radiator cap on a hot engine.

    

3. Tire pressure. Check the pressure of each tire using an accurate gauge when the tires are cold (less than 5 miles of driving). The recommended tire pressure is frequently found on a plate on the driver's side doorpost. The maximum allowed tire pressure is on the tire itself. Do not over inflate the tire. Hot tires will have higher pressures; do not exceed this pressure if air must be added to one low tire after driving to a service station to get air.

    

4. Windshield Washer Fluid. Seeing the road is very important! Clean both the inside and the outside of the windshield. Check the level of washer fluid in the reservoir. This is a second reservoir under the hood and should show a windshield wiper symbol or say washer fluid on the cap. Plain water can be used but it will not clean very well and might freeze in winter. Wipers move better with the proper fluid. Inexpensive premixed washer fluid is available in auto stores for this use. Fill the reservoir as needed.

   Containers of glass cleaner and paper towels are good supplies to have handy for cleaning the inside of the windows. A film frequently develops there on the inside that hinders vision.

    

5. Brake Fluid. The brake fluid transmits the force applied to the brake pedal to the brake pads located at each wheel. The fluid is required for proper brake operation. The reservoir is located under the hood in front of the driver near the steering column. The fluid level will go down as the brake pads wear. Maintain the level between the minimum and maximum levels.

    

6. Automatic Transmission Fluid (ATF). Read your operator's manual for details on checking the fluid level and for the type of fluid to use in your car. Depending on driving habits, the fluid may be good for years or may require servicing at intervals. The fluid is checked with the car running so follow directions carefully and beware that the radiator fan may start at any time.

    

7. Power Steering Fluid. A small reservoir near the pump should be checked. The pump is driven by the engine and may be down low next to the engine on the driver's side of the engine compartment. The reservoir may have a dipstick or may be transparent so the maximum and minimum levels can be seen. Check the operator's manual to learn the correct fluid to use for your car.

These are the quick check items to be done on a frequent basis. Filling the gas tank might have been included but that one seems to be the first one everyone learns to pay attention to while driving. Maybe once a week seems too often for these checks. Driving habits and the condition of the car should determine the frequency. Find something or some way to remind you to do these simple checks. It can save dollars and help avoid expensive maintenance bills from a repair shop. Good Luck!

David S. Ross, Extension Agricultural Engineer

Whether it means tending to a collection of exotic house plants or cultivating a year-round crop of vegetables, greenhouse gardening appeals to many people for many different reasons. A greenhouse can help garden-enthusiasts get through the cold part of the year; it fills a void during winter, when weather prohibits gardening outdoors. Home greenhouses are ideal for introducing children to nature and showing them how seeds develop into flowering plants or nutritious vegetables. Retirees often adopt greenhouse gardening as a hobby to enjoy during their retirement years.

Greenhouses for Homeowners and Gardeners ($25.00 plus S&H/sales tax, 214 pages, June 2000) will help readers select and design the most appropriate size and style of greenhouse to fit their needs, find the best place to locate a greenhouse, and decide whether to build a greenhouse themselves or hire a contractor to do it. This comprehensive, easy-to-read book covers every style and type of greenhouse - from relatively inexpensive film-plastic-covered growing spaces to custom-designed, cozy sunspaces that extend the living space within the home. The book addresses a wide audience, including gardeners, homeowners, cooperative extension educators, and institutions (such as retirement homes, schools, and prison associations). Small farmers may also find the book useful.

The book contains eight chapters on the following topics: greenhouse basics, selecting a greenhouse, greenhouse planning, framing materials and glazing, greenhouse layouts and equipment, the greenhouse environment, window greenhouses and growth chambers, and garden structures. With this book, aspiring and practicing greenhouse operators will be able to make informed decisions about foundations, glazing and framing materials, space utilization, interior design, heating and cooling systems, supplemental lighting, watering and fertilizing systems, and other greenhouse design and construction issues. The garden structures chapter covers the design, construction, and use of cold frames, hotbeds, shade houses, rowcovers, and high tunnels.

Nearly 150 line drawings illustrate the 214-page book to help readers visualize the way greenhouses are built; evaluate alternative methods of construction; design interiors; select labor-saving equipment; and understand the skills involved in designing, building, and operating a greenhouse. Ten diverse do-it-yourself plans for home greenhouses and other garden structures are provided in an appendix. Each plan includes materials lists and construction diagrams and details. Three additional appendixes contain a greenhouse maintenance checklist, lists of greenhouse and equipment suppliers, and useful conversions. A glossary of terms that might be unfamiliar to readers and an index are included as well.

Greenhouses for Homeowners and Gardeners was written by John W. Bartok, Jr., Professor Emeritus in the Department of Natural Resources Management and Engineering at the University of Connecticut. He wrote the book to update similar publications that have become obsolete due to changes in materials and construction techniques. Bartok has over thirty years of experience working with hobbyists, commercial growers, institutions, and manufacturers. His book was published by the Natural Resource, Agriculture, and Engineering Service (NRAES).

Greenhouses for Homeowners and Gardeners, NRAES-137, is available for $25.00 per copy plus shipping and handling from NRAES, Cooperative Extension, 152 Riley-Robb Hall, Ithaca, NY 14853-5701. Shipping and handling for one copy is $5.50 within the continental United States. If ordering more than one book or if ordering from outside the United States, contact NRAES for shipping rates and possible quantity discounts. All major credit cards are accepted, and checks should be made payable to NRAES. For more information or a free publication catalog, contact NRAES by phone at (607) 255-7654, by fax at (607) 254-8770, or by e-mail at nraes@cornell.edu. To learn more about NRAES, browse through our entire catalog, and order books online, visit our web site at <www.nraes.org>.