Obligation of Johkasou Manager
Johkasou are periodically maintained due to their small scale and designed to minimize the burden imposed on johkasou users. However, it is necessary to consider the fluctuations in the period of maintenance changes in the condition of the unit as well as the change of temperatures throughout the year when operating the unit.
J Also, it is necessary to adjust the operation of johkasou according to the purpose of buildings (houses, shops, schools and so on) where johkasou are installed. To realize performance in line with the design of johkasou, the device must be used correctly. The johkasou manager has a statutory obligation, as the person responsible for the operation of johkasou by users, to periodically conduct maintenance on johkasou and desludge the sludge accumulated in the johkasou as outlined in the Johkasou Law.
Since not every johkasou manager possesses specialized knowledge regarding maintenance and desludging, the business of maintenance and desludging are mainly entrusted to johkasou maintenance vendors and johkasou desludging vendors. Another statutory obligation requires that johkasou managers must receive an annual water quality inspection to evaluate whether the maintenance and desludging of a johkasou were correctly executed and to confirm that the unit is performing as designed. The water quality inspection is executed by an inspection agency specified by the prefectural governor. The general system for maintenance, desludging and inspections of johkasou is summarized below.
Operation and Maintenance
Maintenance operations are necessary to adjust johkasou or repair them as necessary. More specifically, these operations include monitoring the operating conditions of each unit equipment, the auxiliary equipment and effluent quality, in order to discover faults or defects early and take corrective action.
At the beginning of maintenance, it is necessary to check how water flows in the inflow and outflow pipes, the installation condition and the operating condition of each component of equipment, and confirm whether wastewater is quickly treated or not.
Technical innovation of johkasou technology has advanced remarkably. For example, the creation of the moving bed biofilm process in which a medium of high specific area is adopted and capable of catching more bio-mass; the biofilm filtration process, which is an extension of the Contact - Aeration Process have been spreading dramatically in recent years. For operating johkasou employing these processes properly, attention should be paid to preventing media from flowing out, obsessive water levels, conditions of aeration, back washing and sludge accumulation.
Recently, an activated sludge process with MF membrane modules was developed. This is capable of removing nitrogen by using a nitrified water recirculation technique or intermittent aeration technique. To operate this process properly, it is necessary to understand the internal structures and equipment sufficiently. Specifically, regarding the flow rate adjustment device, the adjustment of the automatic back-washing device and membrane separation operation, it is necessary to add seed sludge properly at the beginning of operation, adjust the time of intermittent aeration, and conduct membrane cleaning periodically.
Johkasou maintenance contractors responsible for operating and maintaining johkasou must be licensed by prefectural governors. The licensed contractors must employ qualified johkasou operators who are certified by either passing a national examination or completing a set of lecture courses designated by the Minister of the Environment.
Desludging
Desludging of johkasou involves removing the generated sludge and scum from the johkasou and conditioning sludge in the tank. The primary purpose of desludging is to remove sludge before accumulated sludge flows out with the effluent.
Johkasou desludging contractors responsible for desludging johkasou must be approved by municipal mayors. The approved contractor must employ a qualified johkasou desludging technician who has specialized knowledge and experience in desludging and has qualified by completing a lecture course known as the “Training course for qualifying johkasou desludging technician.”
Legal Inspection
According to the Johkasou Law, johkasou managers must be aware of installation and operation conditions, objectively measure the treatment performance of johkasou and see that johkasou water quality is inspected by the Specified Inspection Agency.
There are two kinds of legal inspections: inspection after construction and annual inspection. Periodical maintenance and desludging for johkasou are akin to daily health upkeep for the johkasou, and the annual inspection can be thought of as a medical examination for johkasou. Through the annual inspection, a johkasou is checked to see whether or not it is being maintained in a normal condition as it is objectively inspected by the specified inspection agency that works as a public service corporation.
