Another limitation says that wastewater is a combination of liquid and liquid waste originating from residential, commercial, office and industrial areas, together with ground water, surface water, and rainwater that may be present (Haryoto Kusnoputranto, 1985).
Waste, garbage, and dirt originating from households, companies, and/or vehicles are serious problems that need attention to create environmental health. Disposal of household waste is accustomed to trash bins, therefore trash bins should always be available in the residential environment according to its type, wet waste (garbage), dry waste (rubbish), and industrial waste (industrial waste).
In addition, the habit of spitting, urinating and defecating (human excreta), wastewater (sewage) must also be managed properly so as not to interfere with environmental health. Garbage that is not managed properly can become a breeding ground for animals that spread disease and unpleasant odors. Although it is residual water, the volume is large because approximately 80% of the water used for daily human activities is disposed of again in a dirty (polluted) form. Furthermore, this waste water will eventually flow into rivers and seas and will be used by humans again.
Therefore, this waste water must be managed and/or treated properly. This wastewater comes from various sources, broadly it can be grouped into the following:
1. Waste water sourced from households (domestic wastes water), namely wastewater originating from residential areas. In general, this wastewater consists of excreta (feces and urine), water used for washing kitchens and bathrooms, and generally consists of organic materials. For example, the project at PT Tarunakusuma Purinusa, Bawen, Semarang Regency
2. Industrial waste water originating from various types of industries as a result of the production process. The substances contained in it vary greatly according to the raw materials used by each industry, including: nitrogen, sulfides, ammonia, fats, salts, dyes, minerals, heavy metals, solvents, and so on. Therefore, the treatment of this type of wastewater becomes more complicated because it must consider its impact on the environment. Examples such as in the Jababeka Kasawan industrial project and the Surya Cipta industrial area
3. Municipal waste water, namely waste water originating from offices, trade, hotels, restaurants, public places, places of worship, and so on. In general, the substances contained in this type of wastewater are the same as household wastewater. An example is the Bali Public Works project
The characteristics of wastewater need to be known because this will determine the proper treatment method so that it does not pollute the environment. Broadly speaking, the characteristics of this wastewater are classified as follows:
1. Physical characteristics
Most of it consists of water and a small part consists of solid materials and suspensions. Especially household wastewater, usually has a dim color like a soap solution, slightly smells. Sometimes it contains paper scraps, colored rice and vegetable washings, parts of feces, and so on.
2. Chemical characteristics
Usually this waste water contains a mixture of inorganic chemicals derived from clean water and various organic substances derived from the decomposition of feces, urine and other waste. Therefore, it is generally alkaline when it is new and tends to become acidic when it starts to rot.
Organic substances in wastewater consist of 2 combinations, namely:
- nitrogen-containing compounds, eg urea, proteins, amines and amino acids.
- compounds that do not contain nitrogen, eg fats, soaps and carbohydrates, including cellulose
3. Bacteriological characteristics
The content of pathogenic bacteria and coli group organisms is also present in wastewater depending on the source, but they do not play a role in the wastewater treatment process.
In accordance with the substances contained in wastewater, untreated wastewater will cause various health problems for the community and the environment, including:
1. Being a transmission or media for the spread of various diseases, especially cholera, typhus abdominalis, bacillary dysentery.
2. Become a medium for the proliferation of pathogenic microorganisms.
3. Become a breeding ground for mosquitoes or a place for mosquito larvae to live.
4. Causes an unpleasant odor and an unpleasant sight.
5. It is a source of pollution of surface water, soil and other living environment.
6. Reducing human productivity because people work comfortably and so on.
In order to prevent or reduce the adverse effects mentioned above, conditions, requirements, and efforts are needed in such a way that the wastewater is. PJLEnviro itself has contributed to reducing this by providing WWTPs to change Indonesia for the better. However, as a society of course we can do several things that can reduce these bad consequences :
1. Do not contaminate drinking water sources.
2. Do not pollute the ground surface
3. Do not pollute water for bathing, fishing, river water, or recreational areas.