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  • Institutional Development for Septage Management

    September 10, 2015 Kazushi HASHIMOTO

    Adviser Japan Sanitation Consortium

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    P.3-2

  • Table of contents 1. Decentralized Wastewater Treatment System (DEWATS) 2. What happens, if DEWATS is not regularly desludged? 3. What is essential for decentralized wastewater

    management? - Septage Management 4. Institutional Framework for Septage Management in Japan (Appendix) 1. Malaysias effort toward establishing effective Septage

    Management System 2. JSCs comments on Septage Management Plan for Aizawl

    City, Mizoram State, India 3. Basic parameters shared by Septage Management experts in

    Japan 2

  • 1. Decentralized Wastewater Treatment System (DEWATS)

    Septic Tank

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  • 1. Decentralized Wastewater Treatment System (DEWATS)

    BORDA DEWATS

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  • 1. Decentralized Wastewater Treatment System (DEWATS)

    Packaged Aerated Wastewater Treatment Plant (PAWTP Johkasou in Japan)

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  • 1. Decentralized Wastewater Treatment System (DEWATS)

    Comparison of DEWATS Septic Tank BORDA DEWATS PAWTP

    (Johkasou)

    Treatment Process

    Anaerobic (Electricity not

    required)

    Anaerobic (Electricity not

    required)

    Aerobic (Electricity required)

    Effluent Water Quality (BOD)

    100-200 mg/l 50 mg/l 20 mg/l

    Nitrogen removal Not removed Not removed Removed

    Coliform removal Poor Poor

    Removed (disinfection)

    CAPEX per person in developing countries

    US$ 80-150 US$ 90-100 US$ 210-380

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  • 2. What happens, if DEWATS is not regularly desludged?

    Any wastewater treatment system ceases to treat and becomes a pollution source.

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  • 2. What happens, if Septic Tank is not regularly desludged ?

    If the septage volume exceeds one-third the capacity of the tank, solid-liquid separation decreases since the retention time of the wastewater decreases. BOD removal is hampered since the inflow of wastewater agitates the accumulated sludge causing inflow wastewater to pass through the tank without treatment. Moreover, a part of the accumulated sludge in the tank flows out together with the untreated wastewater, leading to further deterioration in the water quality of the effluent of the septic tank. (Source : USAID) 8

  • 2. What happens, if Septic Tank is not regularly desludged ? (Indonesia)

    Volume ()

    Usage (persons)

    Effluent water quality Remarks BOD COD mg/l mg/l

    Black water only type 1

    6.0 15 145 421 Desludged once a year.

    Black water only type 2

    2.2 4 231 622 Desludged twice a year.

    Black water only type 3

    2.9 4 217 544 Never desludged.

    Black & Grey type 1

    7.4 4 206 419 Not desludged (4 years)

    Black & Grey type 2

    10.0 40 162 367 Not desludged (3 years)

    Black & Grey type 3

    10.0 18 213 401 Not desludged (3 years)

    No septic tank meets the effluent standard established by the Governor of Jakarta City Government for household septic tank (BOD75mg/l, COD100 mg/l). Irregular desludging may be one of the causes.

    9 (Source : JICA)

  • What happens, if Septic Tank is not regularly desludged ? (India)

    FIELD EVALUATION OF CONVENTIONAL SEPTIC TANKS (Presented at the IWA Side Event (Dec. 2014) by Prof. A. A. KAZMI,

    DEPARTMENT OF CIVIL ENGINEERING, IIT ROORKEE, India)

    STE: Septic Tank Effluent

  • 2. What happens, if PAWTP (Johkasou) is not regularly desludged ?

    Sludge accumulates quickly in a PAWTP since its wastewater treatment efficiency is high. It must be desludged once a year to maintain its performance standard.

    After one year After three years

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  • 2. What happens, if PAWTP (Johkasou) is not regularly desludged ?

    A research, conducted in 1984 for 70 PAWTPs (black water only type) in Japan, revealed that 24.6% of them had not been desludged for more than 1 year, and their average effluent water quality (BOD) was worse than the ones which had been desludged with less than 1 year intervals.

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  • 2. What happens, if BORDA DEWATS is not regularly desludged ?

    [Required desludging frequency] Settler : once in two years Baffled reactor : once in five years

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  • 3. What is essential for the decentralized wastewater management ?

    [1] Introduction of the regular desludging system. Regular desludging = the sludge will be removed from the tank periodically regardless whether it is full or not, as a preventive maintenance of DEWATS.

    [2] Proper disposal of the sludge removed from DEWATS.

    Septage Management !

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  • 3. What is essential for the decentralized wastewater management ?

    [1] Introduction of regular desludging system

    (1) Desludging must be the legal obligation of all the owners of any DEWATS.

    (2) There must be the trained good desludging operators. Formalize them, if there are existing desludging operators. Let them make companies. Establish the licensing system and training system.

    (3) Data base of all DEWATS in the City. Both the municipality and the desludging operators should have it.

    (4) Use vacuum truck for the more efficient and hygienically safer de-sludging operation.

    (5) Use the sludge relay tank to shorten hauling time. (6) Improve the DEWATS for the efficient desludging.

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  • 3. What is essential for the decentralized wastewater management ?

    Regulatory Framework is necessary !!!

    Residents do not worry about the septic tank unless it becomes full of sludge, overflow and their toilet becomes unusable. Communication strategy is necessary but not enough. Regulation is necessary.

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  • 3. What is essential for the decentralized wastewater management ?

    These peoples are the most important !!!

    PAWTP De-sludging Technician PAWTP Inspector

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    Existing desludging operators in Mizoram State, India, who are conducting desludging of septic tanks using a pump and a water tank mounted on a truck.

  • 3. What is essential for the decentralized wastewater management ?

    Economics matters !!!

    The most expensive item for septage management is not the DEWATS itself but the cost for desludging. Desludging of one septic tank (3 ) costs US$30 in Jakarta, US$50 in India, US$70 in Malaysia, US$250 in Japan.

    In Japan, the desludging is considered not a profitable business unless at least 4 PAWTPs can be desludged by one vacuum truck. Efficiency matters.

    In Japan, many desludging operators cover 7 PAWTPs daily and make money.

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  • What is essential for the decentralized wastewater management ? Technology

    Use of Vacuum Truck will ensure the efficient and hygienically safe desludging operation.

    Vacuum Truck Truck + pump Time required for emptying

    Septic tank (3) 40 minutes PAWTP (5PE) 30 minutes

    Septic tank (3)2 hours

    Discharge of the sludge

    10 minutes Quick because the caliber of the hose is bigger (45-65mm)

    30 minutes Slow because the caliber of the hose is smaller (32mm)

    Possibility of the human contact with the pathogen

    None Possible at the time of connecting and disconnecting the hose to the tank.

    These vacuum trucks shall be leased to the existing desludging operators. (Photo taken in Mizoram State, India)

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  • 3. What is essential for the decentralized wastewater management ? Technology

    Sludge relay tank will improve the efficiency of desludging operation by shortening the hauling time.

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  • 3. What is essential for the decentralized wastewater management ?

    Technology DEWATS must be desludging friendly !!!

    It must be reachable for the desludging operators. (1) It must be installed in the open air space. (2) It must have manholes. It would be the most convenient if the partial

    desludging could effectively remove all the sludge without removing the water contents.

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  • In case of septic tank, you need to remove all the contents of the tank.

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  • PAWTP (Johkasou) consists of four (4) separate compartments. Since the sludge accumulates only in two of them due to the water flow caused by the blower (air lift effect), the partial desludging effectively removes all the sludge. The water contents of the tank does not need to be removed.

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  • 3. What is essential for the decentralized wastewater management ?

    [2] Proper disposal of the sludge removed from DEWATS

    (1) Local municipalitys obligation to develop septage/sludge treatment facility. Central governments obligation to provide financial support to Local municipalities.

    (2) Sludge drying bed is an appropriate method if land is available.

    (3) If there is a Sewage Treatment Plant (STP) nearby, co-treatment at the excess sludge treatment section of a sewage treatment plant is the best option. Proper pre-treatment facility is required to minimize the adverse effect on the operation of STP.

    (4) Independent septage/sludge treatment facilities - In Japan, there are 1,100 independent night soil/sludge treatment plants of various technologies.

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