Ch. 12 Solid and Liquid Wastes

Medical Waste

". . . any solid waste that is generated in the diagnosis, treatment, or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biologicals . . ."

Definition of Sewage

"The wastewater generated by people in homes and businesses."

Landfill Design

A landfill is composed of four major parts: - a bottom liner - a system for collecting leachates - a cover - an appropriate location that minimizes the contamination of groundwater by materials released from the site

Incineration

Can be used to generate energy while at the same time reducing the volume and weight of waste

Problems Caused by Growing Volume of Waste

Difficulties in disposal Dump sites being used up Increases in pollution Increases in costs of disposal

EPA's Hierarchy for Management of MSW

From more favored to less favored - Source Reduction - Recycling - Disposal

Emissions from Landfills

Generation of methane, volatile organic compounds (VOCs), and other gases

Federal Landfill Standards

Location restrictions Liners Operating practices Groundwater monitoring Closure and postclosure care Corrective action Financial assurance

Modern Sewage Treatment and Disposal

Modern technology involves : - Removing solids - Deactivating microbes - Producing wastewater that can be returned safely to waterways or in some cases can be reused or recycled.

Components of the Municipal Solid Waste Stream

Packaging Furniture Clothing Bottles Food waste Papers Batteries Organic materials

The Four Dimensions of MSW Disposal

Recycling Landfilling Composting Combustion

Secondary Stage of Sewage Treatment

Secondary processing promotes microbial digestion of organic material that remains in the sewage.

Source Reduction

Source reduction refers to ". . . reducing the amount of waste created, reusing whenever possible, and then recycling what is left."

Recycling

The EPA defines recycling (reuse) as the process of "Minimizing waste generation by recovering and reprocessing usable products that might otherwise become waste (i.e. recycling of aluminum cans, paper, and bottles, etc.)."

Primary Stage of Sewage Treatment

The primary stage aims to remove large materials, which can be composted or shipped to landfills.

Components of Source Reduction

Two important components - Waste reduction aims to reduce the amount of waste produced at the source. - Waste recycling refers to reuse of materials in the waste.

Composting

• ". . . the controlled decomposition of organic materials, such as leaves, grass, and food scraps, by microorganisms." • Produces a useful material that resembles soil and that can be used in gardening.

Other Methods for Sewage Disposal

• Composting toilets • Septic systems

Disadvantages of Incineration

• Emissions may be potentially hazardous to human health and the environment. • Toxic materials emitted may cause air pollution or be deposited on the land.

Megafills

• Megafills take in from 5,000 to 10,000 tons of trash per day and serve regional needs for waste disposal. • Tend to be more cost effective than incinerators for disposal of solid waste.

U.S. Sewage Requirements

• Most jurisdictions in the U.S. require that wastewater receives at least secondary treatment. • Water that has received only primary treatment is not recommended for any use and generally needs secondary or tertiary treatment for common purposes such as landscape irrigation.

Advantages of Recycling

• Reduces emissions of greenhouse gases • Prevents water pollution • Decreases the amount of materials shipped to landfills • Preserves raw materials and energy Opens up new employment opportunities

Tertiary Stage of Sewage Treatment

• Tertiary (high-level) processing is directed at removal of remaining solids and microorganisms from the liquid portion of sewage. AKA "polishing" • Method: sand and charcoal filters and deactivation of microorganisms by using chlorine or UV radiation.

Municipal Solid Waste (MSW)

• This is trash or garbage. • Between 1960 and 2003, the United States—residents, businesses, and institutions—generated approximately 236 million tons of MSW (before recycling).

Love Canal

• Was the site for disposal of toxic wastes • Later used for residential construction • Became identified with hazardous chemical exposures and their possible harmful influences on human health • Led to the creation of the Superfund