From a very broad sense, waste water is any water that has been influenced or adversely affected by the actions of man. So, this category is actually quite general in its scope. Domestic, agricultural, commercial and industrial sources all fall into this category. This definition also encompasses storm water run-off and any water impacted by sewage.
In larger cities such as Glasgow, London or Birmingham, waste water is treated at a centralised plant. This water will arrive from a property to the plant via the use of a combined sanitary system (simply referred to as a sewer). Locations that are suburban or rural will instead utilise on-site options such as a drainage field or a septic tank. Treating any waste water will fall into the larger topic of sanitation. There are some issues which can overlap while there are other variables that are specific to waste water itself. Let us begin by looking at the current regulations and governing bodies before moving on to treatment methods and the modern technologies which are employed to help protect the environment.
Current Regulations Governing the Handling and Treatment of Waste Water
First, the Environment Agency requires permits for various types of waste water-related activities. The proper documentation is required if:
* One owns any type of installation (such as a factory or a laundrette) that is known to produce waste water.
* Any operation is undertaken (such as mining or recycling) that is known to produce liquid waste.
* A facility discharges pollutants into bodies of water such as lakes or streams.
Although the bulk of these operations will require direct oversight by the Environment Agency, there may be times (such as during solvent emissions that could potentially leech into the groundwater) that one's local council will also need to be contacted.
Please note that currently, the United Kingdom also falls under the directives of the European Union in regards to the treatment and disposal of waste water. First adopted in 1991, the Council Directive 91/271/EEC deals with protecting the environment from the effects of urban waste water (2). The three main water types as defined by this directive include:
* Domestic waste water.
* Water derived from a mixture of domestic and industrial sources.
* Water produced as a by-product of specific industrial sectors.
There are also individual stipulations governed by the EU which address sewage treatment plants and private facilities. Individuals or organisations that do not comply with such regulations can be subject to fines and even criminal charges. As this information is quite extensive, it is always best to consult with the proper authorities to determine the appropriate legislation that pertains to a specific category.
As this type of water is so pervasive, it only stands to reason that there are a number of different approaches to protect the environment against its impacts. The ultimate goals are to render it safe for human consumption or to return it to the natural surroundings with little (or no) impact. There are three primary processes employed.
1. Phase Separation
This method involves separating the solids within the water into a non-aqueous state. As a result, they can be more easily removed and the water is considered much safer. Some of the primary ways that this is accomplished is through sedimentation (the simple act of gravity over time) and filtration.
Organic compounds can also be dissolved within the waste water. As these go through the process of oxidation (chemically breaking down), they render potentially toxic compounds safe. Bacteria are often used in this case and this is quite similar to the methods used when treating sewage or sludge.
This final process involves a combination of the two previously mentioned approaches. However, polishing normally also modifies the pH of the water; helping to minimise its subsequent reactivity. The water may also be filtered again using common substances such as sand or fabrics.
4. Nanotechnology as a Cleansing Method
This is considered to be more of an emerging technology than one which is currently applicable on a nationwide level. Nanotechnology involves the use of machines that are the size of molecules (and sometimes even smaller). These tiny powerhouses can be literally programmed to perform certain tasks. As a result, they will break down volatile or toxic substances within the water much more efficiently than more traditional techniques (3). Although this method is still emerging, it promises to be one of the most environmentally friendly options in the future.