Messages from Departments and Centers of NILIM

Aiming at Improvement in Sewerage Management
TAKASHIMA Eijiro, DirectorWater Quality Control Department
Keywords: comprehensive strength, management, total balance

1. Sewerage system provides ultimate service
Treatment of excrement and wastewater is very
important for communities. With sewerage systems, thesecan be easily treated. With an urban piping network,
waste matter can be transported utilizing water andgravity.
Sewerage system users are required to pay a sewerage
service charge for the benefit of using the system and afee based on the polluter-pays-principle for treatment ofpollution in public waters. Sewerage service covers not
only communities but also the natural outdoors andenvironments, such as aquatic eco-systems.
Sewage consists of wastewater and rain water, as thetreatment of rain water is also essential for communities.
In Japan, a tax is used to fund measures to drain rainwater, but that tax and sewerage service charge are thesame in that they are both paid by residents. Waste
water and rain water are quite different in how quantity ismeasured and how they are treated, as well as in quality,
so sewerage personnel must have broad knowledge about
them.
Sewage contains biomass energy, resources such as
nitrogen and phosphorus, and heat, which are discharged
as a consequence of human activity. Technologies forrecovering and utilizing these resources are progressing.
Such technologies should be further developed andexpanded by solving cost problems in order to contributeto the formation of a recycling society.
2. Some specific areas of sewerage management
The key to management must be comprehensive
strength. Without a total balance amongst organization,planning, construction and reconstruction, operation,maintenance, and financial considerations, it is difficult tosustain the management of works in the future.
Moreover, there are some specific areas of seweragesystem management. This section highlights keywords
and matters of interest concerning these areas.
(i) Stock management: Safety assurances, function
maintenance, reduction of life-cycle costs, costequalization, etc.
As a special note, total length of sewage pipes laid hasreached about 450,000 km, equivalent to slightly morethan 11 circles around the earth, and a sharp increase in
old pipes is henceforth expected. It is, therefore, an
important priority to establish efficient measures in orderto prevent disasters by studying past cases of roadsubsidence due to deteriorated sewage pipes, as well as
data concerning pipeline degradation. It is also necessary
to accelerate the planning of efficient measures that areaffordable even to local governments with small budgets.
Such measures may include the development,
introduction, and evaluation of accurate, quick, andcost-efficient methods for surveying and diagnosing
deterioration, as well as life extension measures such aspartial restoration.
(ii) Water environment management: Water quality
conservation in public waters, improvement of water use
systems, rain water management, etc., required from abroad / recycling viewpoint.
It is necessary to keep a good balance between theamount of energy used for water quality improvement /water utilization and the level of water treatment. For
what regards the water quality of public waters, such asbays, management has recently been requiredconsiderations for balanced ecosystems, fishery resourcesand other facets rather than focusing entirely on reducingnutrients. In addition, to control damage caused byinland water inundation, it is required to properly assess
the capability of existing infrastructure and establish
measures to mitigate inundation damage caused by
localized heavy rains, etc. in cooperation with sewerage
and river projects, and other organizations.
(iii) Energy resource management: Recovery ofnutrients and energy from sewage, control of greenhousegases (CO2, N2O, etc.), and recovery of urban waste
heat.
The Breakthrough by Dynamic Approach in Sewage
High Technology (B-DASH) Project is underway todemonstrate advanced technologies. From 2014, theprojects, such as producing hydrogen from sewage sludge
and developing energy-saving water treatment, havebegun.

(iv) Risk management / Crisis management
As a risk related to water quality, there is the potential
harm to people and ecosystems from chemicals or
pathogenic microbes contained in sewage.
Whenreutilizing sewage treatment water, it is necessary tomanage water quality risks according to application, andshow consideration for such standards. The spread ofsewerage systems has improved the control ofwater-borne infectious diseases such as cholera, which
had killed many people, and extreme water pollution.
However, it is still necessary to evaluate and takemeasures against an enormous number of chemical
substances and medicines in sewage. These substances
are used not only by factories but also at home, and flow
into the environment via sewerage systems.
It is also necessary to take preventive steps as well as
responsive action for emergency cases, such as theoverflow of wastewater from sewerage systems, which
occurred in the Great East Japan Earthquake. It is also anurgent issue to take structural and non-structural
measures assuming the occurrence of major earthquakes
and tsunamis.
3. Reinforcement of financial thinking
For sewerage projects, corporate accounting has been
introduced by local governments and the practice isspreading.
Depreciation costs are important forindustries with very large fixed assets such as a seweragesystem. To depreciate costs means to account for theannual decrease in the value of newly installed fixed
assets based on usage as non-cash expense in annual
profit and loss statements. It is also necessary to
account for revenue against costs in a given year.
Depreciation costs are calculated based on thepredetermined length of life of the asset, so if the asset isused in excess of the predetermined life, it will produce
profits.
In some cases, however, life extension may beinappropriate for some sewerage infrastructure and it may
be more appropriate to rebuild the said infrastructure at
relatively short intervals in line with technologicalinnovation.
Infrastructure for resource / energy
recycling is of this type. The materials should be
simplified in light of the recovery of initial costs during
the life of the infrastructure.
The payment of interests arising from a loan for
constructing the asset is also recognized as an expense on
profit and loss statements. Since interests accrue every
day once the construction funds have been borrowed,
efforts should be made to deliver the best possible effectas early as possible.
With such financial thinking, it is important to either
ensure adequate income against expenses (maintenance +depreciation + interest expenses) or adjust expenses inresponse to the estimated income.
The financial situation of most local governments isbad. As depopulation and aging progress, water usage
will fall and subsequently income derived from that usage
is expected to decrease. Under such circumstances, itwould be difficult to ensure business sustainability
without addressing stock management, risk management,etc.
Accordingly, it is increasingly necessary to simplify
matters by applying past experience to reduce costs andset priorities, etc. However, it should be noted that
failure to ensure financial resources for proper
maintenance will shorten the life of the infrastructure andcause problems.
Furthermore, measures to increase the value of existing
infrastructure should be aggressively considered. Suchmeasures might include energy generation using local
biomass other than sewage.
4. Roles of NILIM
Local governments take charge of sewerage projects
and their financial and technical capabilities are various,ranging from big cities to small municipalities.
The roles of our department in NILIM are as follows.
(1) Raising technical capability across the country bymeans of analysis, evaluation, and development ofadvanced findings and technologies. (2) Utilization of awide range of information, including existing
maintenance results, from all over the nation. (3)Introduction and evaluation of technical developmentsthat particularly lead to cost reductions. (4) Making
such information available to local and regional
governments and other stakeholders.
Therefore, we will promote the study of technicalpolicies for sewerage systems with the aim to improve
management in ways that maintain a total balance.