ESTABLISHMENT OF PERFORMANCE INDICATORS IN ENVIRONMENTAL ASPECTS FOR A MECHANISED SEWAGE TREATMENT PLANT AS A GUIDELINES TO MALAYSIAN AUTHORITIES

SITI RASHIDAH MOHD NASIR,
ASSOC. PROF. IR.DR. AMINUDDIN BAKI, 
ASSOC. PROF. IR. DR. SUHAIMI ABDUL TALIB
IR. MOHD. TAUFIK SALLEH
 

Faculty of Civil Engineering, Universiti Teknologi MARA
Indah Water Konsortium Sdn. Bhd.
sitir015@salam.uitm.edu.my
 

INTRODUCTION

Prior to the development of ISO TC 224, countries around the world have operated wastewater treatment plant according to their own standards.  Nowadays wastewater service operators are feeling the pressure to improve the performance of services, increase efficiency, and enhance customer service while simultaneously reducing environmental impacts and lowering rates.  They have to strive for high degrees of effectiveness and efficiency in order to achieve the performance goals. A set of performance measures called the Performance Indicators (PI) are required to quantify particular aspects of performance or standard of services achieved by the service provider.  This set of PIs assists the monitoring and evaluation of the effectiveness and efficiency of the service provider.   

            International Water Association (IWA) has recently established a system of standard PI for wastewater services.  This system acts as a comprehensive management tool for the wastewater service provider which taken into account issues regarding level of development and climatic, demographic and cultural characteristics of the regions.  This paper intended to covers environmental aspects related to mechanised STP. Therefore, due to the increasing pressure, Malaysia has yet to establish a set of PIs for the wastewater service provider. Hence, this paper is intended to study and establish a set of PIs governing environmental aspects for STP as guidelines for Malaysian wastewater regulators and service provider. 

A case study was conducted at STP at Section 23 Shah Alam to establish the set of PI for a mechanized STP. The performance results of this treatment plant shall be use for the purpose of identifying ‘best practices’ that could be emulated in other STP.  The PIs established can be used as a guideline to the Indah Water Konsortium Sdn Bhd (IWK) to measure their performances.  In addition, these PIs will provide the regulator, Department of Sewerage Services (DSS) in Peninsular Malaysia and the local authorities in Sabah and Sarawak, a benchmarking tool to compare the performance of service operators, in terms of their services and costs in a systematic manner.    

METHODOLOGY

In order to establish the PIs for the wastewater services, a structured survey, in the form of a questionnaire and interviews based on the performance measurement indicators described above, was conducted. Questionnaires and interviews question were designed based on the IWA guidelines for wastewater services.  For this research two (2) different rating was used namely current usage rating (based on IWA guidelines) and respondent’s opinion rating.  This is to identify the difference between current PI usage and the respondent’s opinion on PI.   Likert’s Scale was used to rate the indicators.  For Current rating the lowest scale, which is Never to a highest scale of All the time while Respondent’s Opinion rating, the lowest scale is Strongly disagree to a highest scale of Strongly Agree.  The respondents involved in the survey were chosen from the level of manager and engineers who personally involved in handling personnel and quality of services of the treatment plant. Prior to the full-scale survey, a pilot study was conducted with IWK Section 23 Shah Alam to test on the questionnaire's reliability, clarity and its effectiveness. For the full-scale survey as shown in Table 1, there were thirteen (13) questionnaires sent to IWK and twelve (12) were sent to DSS.   In addition, individual interviews were arranged with twenty (20) respondents of different departments; more specifically eight (8) from the DSS and twelve (12) from the operational and maintenance department as shown in Table 2.  The interviews were intended for gathering further comments, elaboration and interpretation on the results obtained from the questionnaire.

 Results from the respondents were then analysed using Relative Importance Index to determine the most important PIs selected by both parties.  In order to determine the relative importance of those indicators, the scores were aggregated and transformed to relative importance indices based on the following formula; Relative importance index (RII) =  Σw/(A*N), where w is the weighting given to each factor by the respondent, ranging from 1 to 4; ‘1’ is the least important and ‘4” is the extremely important, A is the highest weight; in this study it is 4; and N is the total number of samples. The RII shall be a variable ranging from 0 to 1.  To compare the difference data from IWK and DSS, three categories of PIs were established namely, PI accepted, PI rejected and PI to be considered.  The PIs to be considered were further analysed to determine its viability for implementation.  By conducting this, an initial set of PIs was established indicating the most acceptable PIs by both parties.  Following the initial establishment, a case study was conducted at Section 23, Shah Alam treatment plant in order to run the initial set of PIs.  Consequently, the initial set of PIs were again divided into three (3) different categories namely, PIs matching IWA guidelines, modified PIs according to data collected in Malaysia and lastly, PIs matching IWA guidelines are not applicable in Malaysia as data are not available   

TABLE 1: Distribution of Questionnaires

 TABLE 2: Distribution of Interviews 

RESULTS AND DISCUSSION

The results from the questionnaires can then be analysed by using RII method to determine the most important indicators for the wastewater industries.  Having this rating calculated, the PIs are ranked accordingly.  PI with values within 0 to 0.5 will be rejected.  PI with values within 0.5 to 0.75 can be considered and PI with values within 0.75 to 1.0 is acceptable.  These data is shows in Figure 1, which indicates PIs acceptable, reject or to be considered for wastewater services.  Table 3 to Table 5 summaries the results:

TABLE 3: PI Accepted by IWK and DSS 

TABLE 4: PI Rejected by IWK and DSS 

TABLE 5: PI to Be Considered 

After considered the PI Accepted and PI Rejected, PI TBC can simply be calculated and the percentage of PI TBC is tabulated in Table 5.  By comparison, DSS received the highest percentage of 46.6% of the PIs to be further consideration than IWK which responded 40%.  

 Figure 1:  Percentage Distribution of Environmental

 In determining the acceptance of this PI, interviews were conducted with the personnel who specialized on those areas in order to gain holistic view and additional information on the PI.  The process in considering these PI were done by taking into consideration of important aspects such as Malaysian weather, the possibility of successfully implementing the PI, adopting PI in the current STP system, the material used at plants and the suitability of adopting the PI.  The PI is also taking into consideration of both parties IWK and DSS interest.   Some of the PIs are found to be irrelevant and unsuitable to be used in Malaysia environment.  The PI to be considered has been carefully analysed and listed in Table 6.  

TABLE 6 : Discussion of PI To Be Considered

There are six (6) numbers of the PIs rejected and only two (2) nos. of PIs were accepted.  However, there is only one (1) no. of PI require modification to suit Malaysia monitoring system. Those modified PIs are shown in Table 7 as below: 

TABLE 7:  Modified PI 

In Table 7 above and according to IWA, in determining PI for Intermittent Overflow discharge frequency, it requires number of overflow discharges that occurred during

assessment period x 365 / assessment period)/ number of overflow devices at the reference date.  However, these data is unavailable from IWK and therefore, it is suggested that this PI can be accepted if   frequency occurrence of overflow is adopted.

Initial set of PI for operators (IWK) and regulators (DSS) of wastewater services in Malaysia

The list of initial set of PI prior to the Case Study at Section 23 Shah Alam Sewerage Treatment Plant is listed in Table 8.

TABLE 8: Initial set of PI

 Case Study and Trial Run at Section 23 Shah Alam Sewerage Treatment Plant 

A case study is conducted to determine the suitable and the most important PIs from the initial set of PIs.  Although initial PIs have been established, not all of them can be used as the data may not be available from IWK.  Therefore, a trial run is required to eliminate the consequences.  The treatment plant at Section 23, Shah Alam providing services to Shah Alam region which has capacity of 380,000 P.E.  The peak flow of the influent is 22 million gallon per day.  The influent characteristic is 250 miligramme per litre and 300 miligramme per litre for BOD and SS respectively.  The plant  is Conventional Activated Sludge system. 

Case Study Discussion 

After evaluated the PIs, it shows that some of the PIs can be generated and some need further modification while the remainders cannot be used at all as the data is unavailable.  Thus, in order to summaries the results, three (3) categories were introduced namely:

 i) PI matching IWA guidelines;

ii) Modified PI according to data collected in Malaysia

iii) PI matching IWA guidelines are not applicable in Malaysia as data are not available

The PIs is tabulated in Table 9 and Table 10. 

PI matching IWA guidelines 

Among the 8 nos. of initial PIs, only six (6) nos. are according to IWA guidelines as listed in Table 9.  This contributes to 75% of the total initial PIs.  However, in Section 23 Shah Alam Treatment Plant, some of the data that stated “nil” is not available but it may be available at other treatment plants.  Therefore, these PIs are still included in this category. 

 TABLE 9:  PIs matching with IWA guidelines 

 Modified PI according to data collected in Malaysia 

PI with coding wEn8, Sludge disposed, requires data of dry weight of sludge handled that is disposed in landfill, incinerated or by any way of disposal and data of all dry weight of sludge handled.  However, the data collected from IWK and evaluated in the IWA’s PIs does not show the true condition. This is because sludge disposed in IWK has a different solid content compare to other countries.  Thus, it is recommended that this PIs be modified to the more specific variables such as volume of sludge disposed over volume of sludge cake produced.   

TABLE 10:  Modified PI according to data collected in Malaysia 

PI matching IWA guidelines are not applicable in Malaysia as data are not available

 In this final category, only one (1) no. of PI from the total nos. of initial PIs was selected. This PI is not applicable in Malaysia due to unavailable of data.  In other words, these PIs require detail set of data where the data are not a routine data collected by IWK.

TABLE 11: PI matching IWA guidelines are not applicable in Malaysia as data are not available 

CONCLUSION AND RECOMMENDATION 

The initial set of PIs as listed in Table 8 has been critically evaluated to suit Malaysia environment and monitoring system.  Consequently, Table 9, Table 10 and Table 11 are produced showing the three (3) main categories.  By comparison, among the eight (8) nos. of PIs initially established from survey, there are only six (6) nos. of PIs can be implemented.  This contributes to 75% from the initial set of PIs.  There is only one (1) no. require further modification and one (1) no. cannot be implemented.

In accordance to IWA guidelines, these PIs can be implemented by both regulators and operators.  However, selections of PIs are required due to the fact that certain PIs are important to certain parties.  For instance, regulators may adopt wEn1, wEn3, wEn6, wEn7, wEn 8 and wEn9.  On the other hand, the operators should focus in all aspects to gain the benefit of the PIs and the output performance.

The fact that only 75% of PIs can be implemented showed that monitoring system in Malaysia operated by IWK, is different from IWA guidelines as well as other countries. For example, monitoring system in Malaysia is on regional basis while European countries are on plant by plant basis.  Therefore, certain data are not available due to the differences.  In addition, IWK itself has its own PIs to determine their output performance but the data collected are different from IWA guidelines. 

It is recommended that a future study to be conducted to compare IWK’s PIs and IWA guidelines in order to determine the major differences and similarities of the output performance.   Thus, only minor modification will be involved.  This research is beneficial for future research by extending the scope of study in determining value of PI for each treatment plants throughout Malaysia.  Therefore, by having this information, all STP in Malaysia can be benchmarked against the standard values.  This may assist the regulator, DSS, to use this as a benchmarking tool to monitor and control the operators’ performances up to the requirement. 

In future, it is hope that by having these PIs, it may provide a management tools to the operators, IWK, in ensuring their services performance is at the high degree level of effectiveness and efficiency.  In line with the ISO TC 224 objectives, this research may also be extended at international level.  This will allow DSS and local authority to benchmark Malaysia’s wastewater services against other countries.