Recycling Waste Water

Maraknya berbagai kegiatan industri di Indonesia mengakibatkan cadangan air tanah di beberapa daerah mengalami kekeringan. Eksploitasi air tanah yang berlebihan di beberapa kota besar seperti Jakarta, Semarang, dan Surabaya, mengakibatkan terjadinya intrusi air laut dan penurunan permukaan tanah akibat kosongnya sungai-sungai air di bawah tanah.

Several ways to overcome the water crisis such as reforestation of deforested forests and injecting water into dry rivers underground in the rainy season have been carried out. However, this has not been able to solve the problem because ground water reserves will still not be fulfilled as long as the exploitation of ground water by the industry continuesberlangsung.

In order for industrial activities to continue and for the community's need for clean water to be met, the wastewater recycling method is a concrete step that must be taken. Today, ozone technology has emerged as an appropriate technology in the process of recycling industrial and domestic wastewater.

Wastewater treatment

Waste water treatment is generally carried out using the Biology method. This method is the most effective method compared to Chemistry and Physics methods. The waste treatment process with the Biology method is a method that utilizes microorganisms as a catalyst to decompose the material contained in wastewater. Microorganism itself, besides describing and eliminating material content, also makes the decomposed material as a breeding ground. The activated sludge treatment method is a wastewater treatment process that utilizes the microorganism process.

Today the activated sludge method is the most widely used wastewater treatment method, including in Indonesia, this is because the activated sludge method can be used to treat wastewater from various types of industries such as the food, pulp, paper, textile, chemical and drug industries. medicine. However, in the implementation of the activated sludge method there are many problems, including, (1) a large area of sewage treatment plant is needed, bearing in mind that the activated sludge process takes a long time, can take days, (2) the emergence of new waste, where it occurs excess sludge from the growth of microorganisms which then becomes new waste that requires further processing.

The large installation area means that the investment fund is quite large, as a result the use of activated sludge technology has become inefficient in Indonesia, coupled with complicated operational processes considering the activated sludge process requires quite strict supervision such as temperature conditions and bulking control of the sediment process.

New waste is a major problem with the application of the activated sludge method. Waste originating from excess sludge resulting from the activated sludge process requires special handling. This waste in addition to containing various types of microorganisms also contains various types of organic compounds that cannot be broken down by microorganisms. Processing of sludge waste itself requires no small cost. At least 50 percent of the cost of wastewater treatment can be sucked up to deal with the sewage sludge that occurs. As a result, most of Indonesia's sludge waste is usually discharged directly into rivers or buried in landfills (landfills) along with other waste.

Recycling waste water

In 1994 in an international water science technology journal, Hidenari Yasui of Kurita Co., Japan, introduced a process of wastewater treatment innovation by reducing the amount of sludge produced from the activated sludge treatment process. The process of innovation is then known as the zero emission wastewater treatment process. Hidenari Yasui has succeeded in reducing almost 100 percent of sludge effluent by applying ozone technology to the process of treating sludge wastewater.

The active sludge wastewater treatment chart with the application of the ozone system can be seen in Figure 1. In this system some of the sludge is taken to go through the ozonation process in the ozone chamber process. Then the sludge is returned to the active mud chamber. Through the ozonation process, the sludge becomes an easy material to be decomposed and reduced by microorganisms. In the active sludge chamber together with the process of decomposition of wastewater material by microorganisms, there is also a process of decomposition of sludge resulting from the process, so as to create a practical system of wastewater treatment.

Ozone which is an active species of oxygen has a oxidation potential of 2.07V, higher than chlorine which has only an oxidation potential of 1.36V. With high oxidation potential, ozone can be used to kill bacteria (strilization), remove color (decoloration), eliminate odor (deodoration), decompose organic compounds (degradation).

With its multifunctional ability, ozone can decompose sludge which contains mostly bacteria and organic compounds such as phenol, benzene, atrazine, dioxin, and various organic dyes that cannot be decomposed in the active sludge process.

Ozone kills bacteria by damaging bacterial cell walls while describing the bacteria (Collignon, 1994). This is different from chlorine which is only able to kill bacteria. Ozone is also able to kill filament type bacteria such as S Natans, M Parvicella, Thiotrix I and II causing bulking in which solids and liquids are difficult to separate in settling ponds.

By applying ozone technology in activated sludge wastewater treatment, a practical system for wastewater treatment is obtained. Some of the advantages of implementing this system are that sludge sludge can be removed so that further processing and / or river pollution can be avoided, bulking can be removed so that the active sludge process system runs stable, and wastewater can be recycled.

By implementing this system, clean water is no longer containing toxic organic compounds and bacteria that are harmful to health. The water can be reused as a source of water for further industrial activities. It is expected that the utilization of the wastewater recycling system will be able to overcome the problem of groundwater supply in order to sustain industrial activities and the community's need for water. Hopefully.

Author: Anto Tri Sugiarto (KIM-LIPI Research Center) Source: Kompas (10 October 2003)