Sanitary landfills
Sanitary landfills are facilities or sites used to isolate waste from the environment to allow biological, physical and chemical degradation that renders the waste environmentally safe. The chemical changes that occur on the earliest anaerobic stage of decomposition in sanitary landfill are dependent on certain factors. This include; bio oxygen demand(BOD) which is the oxygen needed to break down organic materials present in a given water sample at a specific temperature over a given period. BOD regulates the production of bacteria used in the decomposition of waste and the conversion process of the same to methane gas or leachate and also determines the PH Of the waste. The bacteria act on the refuse and transform the metals to leachate. The increase of bacteria is gradual as period lapses, and the production of methane gas decreases the PH inside the landfill and of which is attributed to the acidity brought forth by the decomposition.
The different types of leachates contain different chemical compositions in their original forms. The sanitary facilities used in storing leachates are either made of PVCs and HDPE geomembranes, which for the first few months hold leachates in excellent resistant conditions and the specified temperatures. There are various factors to consider for future durable geomembranes include flow and oxygen rate, temperature, light, chemical media, reference medium and mechanical stress.
The flow and dissolved oxygen rate should be regulated to reproduce the real environment since the anaerobic condition is more damaging to the polymers since anaerobic micro-organisms find energy in eating molecular chains. The geomembranes should also be strong enough to resist extreme temperatures of a high of 500 and a low of 20 degrees Celcius after the reaction and the beginning of the response respectively. The sanitary facility should be well covered. Aforementioned will prevent the light that accelerates the ageing of the geomembranes by photo-degradation. Real leachates holders, instead of the synthetic holders, should be used so as to contain all the chemical reactions involved in the process. Semi-crystalline polymeric materials should be avoided to reduce mechanical and chemical stresses that cause stress cracks, thus reducing the polymer’s service life.