Serving a large purpose with little consideration, glass is a key ingredient in many of our everyday products. Tableware, light bulbs, mirrors, stove tops, windshields, windows: the list is large for something not given a second thought. Friend or foe, we need to consider the implications of glass making on the environment.
The ‘What Is’ of Glass
Glass is a combination of three types of substances that occur naturally in North America;
- silica, the most popular being white sand
- alkali, such as sodium bicarbonate
Sometimes a metallic oxide (lead) is added to the mix. Depending on which alkali is used and whether or not lead is added, the clarity or color cast of the glass changes. The expense of producing and the quality of the glass is determined by the choice of alkali and the percentage used, combined with the choice and percentage of silica used.
The ‘How’ of Glass Production
A silica, an alkali and limestone are first crushed into a powder form, sifting out any coarse particles. They are then blended and put into a furnace at an extremely high temperature for as long as 24 hours. This yields molten glass which is then cooled several hundred degrees resulting in a thick liquid. The resulting matter is called frit which is then blown, pressed, drawn, molded or rolled into glass objects. If the glass is to be molded the molds are also heated at high temperature so the liquid poured into them does not wrinkle. The cooling process involves washing with water.
Environmental Impact of Glass Production
The process of making new glass is not at all environmentally friendly. The initial crushing and grinding step sends particulates of metals, chemicals, acids and dust into the air. These are easily inhaled causing irritation to the nose and throat, potentially causing damage to the lungs. The particles of metals are hazardous to the environment as they can find their way into surrounding soil and water.
The need for extremely high temperature furnaces to melt the mixture of substances makes the melting stage of the glass making process very energy intensive. It is estimated to take 15.2 million BTUs of energy to produce one ton of glass. During any one of the formation processes the glass may need to be reheated to keep it in liquid form. This means the heat in the furnace must be kept up until the process is complete. bongs online
Discharges from the glass making process may find their way into the aquatic environment during the cooling and cleaning processes where the most significant amounts of water are used. Discharges may contain some pieces of glass, some soluble used in the production like sodium sulfate, lubricant oil used in the cutting process, dissolved salts and water treatment chemicals.
Glass manufacturing processes also emit a significant amount of greenhouse gases especially carbon dioxide. Additionally, the processes spit out air-polluting compounds like nitrogen oxide, sulfur dioxide and particulates.
Benefits of Glass
Glass is nonporous making it impermeable to other substances. For this reason glass is a very hygienic surface as any bacteria and germs that come in contact are not absorbed into its structure. Glass surfaces take to strong cleaning with a disinfectant and hot water with no effect on its quality. For this reason glass containers can be easily reused many times over.
The impermeableness of its structure eliminates any interaction with the stored contents. This, along with glass being made from nontoxic raw materials, dismisses concern of leaching chemicals into the contained substances. In the case of food storage, this also insures the freshness and uncompromised taste of the stored substance. Glass containers also do not absorb the smells of the foods in or around them.
Unlike other materials, glass used in the microwave does not leach any toxins into contained foods or liquids. Nor does it stain, corrode or deteriorate no matter how many times it is reused.