Engineering Solutions
HydropureWater Engineering Team
Medan's Sewage Infrastructure Reality: Two Plants, One Gap
Medan's Pulo Brayan Wastewater Treatment Plant (WWTP), with a design capacity of 10,000 m³/day, discharges effluent with a BOD of 40-55 mg/L and COD between 50-75 mg/L, exceeding Indonesia's 2016 effluent standard of 30 mg/L BOD (S3, 2025-07). This facility utilizes a Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an aerated lagoon, with aerators operating only 4-5 hours daily to reduce energy costs (S3, 2025-07). Concurrently, IPAL Cemara, the city's larger centralized plant under PDAM Tirtanadi, has a maximum design capacity of 60,000 m³/day but currently treats less than 10,000 m³/day, serving only 18,396 households (S4). This represents a utilization rate below 16.7%, and new developments frequently encounter connection delays.
Nationally, only 12 Indonesian cities possess centralized WWTPs, with urban service coverage generally below 5% (S3, 2025-07). To address this gap, the Indonesian government initiated the community-based sanitation (SANIMAS) program, which has implemented over 1,700 decentralized wastewater treatment systems in more than 300 locations across all 27 provinces by 2015 (S3, 2025-07). However, for coastal areas of Medan, a Structural Equation Modeling-Partial Least Squares (SEM-PLS) study confirmed that inadequate waste management practices and insufficient infrastructure directly impact environmental health outcomes for communities (S2, 2025-03). This highlights the necessity for new developments to consider robust, compliant, and often decentralized domestic sewage treatment solutions.
Indonesian Effluent Standard P.68/2016: The Compliance Baseline
Indonesia's Regulation of Environment and Forestry No. P.68/Menlhk/Setjen/Kum.1/8/2016 establishes mandatory effluent quality standards for a broad spectrum of domestic wastewater sources, including apartments, lodging, hospitals, restaurants, settlements, industrial domestic wastewater, and centralized WWTPs (S3, 2025-07). This regulation is more stringent than previous standards, necessitating appropriate treatment technologies to ensure compliance (S3, 2025-07).
A critical parameter often challenging to meet for many conventional treatment systems, particularly biofilters and Rotating Biological Contactors (RBCs) without dedicated nitrification, is ammonia concentration (S3, 2025-07). Pulo Brayan WWTP's actual effluent BOD (40-55 mg/L) and COD (50-75 mg/L) already exceed the P.68/2016 limits, underscoring that any new packaged plant must be designed to outperform existing centralized infrastructure (S3, 2025-07). Beyond regulatory mandates, life cycle assessment (LCA) studies reveal that effluent release is the primary driver for freshwater ecotoxicity, accounting for 72% of CS2 impact, and eutrophication, with 41.25% attributed to NH3 and 39.60% to N (S4). Therefore, effective ammonia removal is not only a regulatory requirement but also a significant environmental priority.
The key effluent parameters for domestic wastewater treatment under P.68/2016 are:
Parameter
Unit
Maximum Concentration
pH
-
6 - 9
BOD
mg/L
30
COD
mg/L
100
TSS
mg/L
30
Oil and Grease
mg/L
5
Ammonia
mg/L
10
Total Coliform
MPN/100 ml
3000
Technology Options for Medan: Matching Process to Project Scale
Packaged A/O (anoxic/aerobic) biological contact oxidation plants, such as the WSZ Series packaged A/O sewage treatment plant, are designed for flows from 1 to 80 m³/h (24-1,920 m³/day) and are suitable for residential clusters, hotels, hospitals, and factories in Medan (S6). These units integrate sedimentation and disinfection, are fully automated, and can be installed below grade or trailer-mounted (S6). For projects requiring superior effluent quality, especially for reuse or stringent ammonia limits below 10 mg/L, an MBR membrane bioreactor system (10-2,000 m³/day capacity) offers a significantly smaller footprint (up to 60% less than conventional systems) and produces effluent with particles less than 1 μm.
Anaerobic-aerobic biofilter systems, typically using PVC honeycomb media with a specific contact area of 200-225 m²/m³, are a standard for SANIMAS communal wastewater systems, implemented in over 300 locations (S3, 2025-07). These systems handle concentration fluctuations well, produce minimal sludge, and are designed for approximately 8-10 Population Equivalents (PE) per individual unit (S3, 2025-07). While Rotating Biological Contactors (RBCs) are used in some Indonesian cities like Banjarmasin for plants ranging from 5-3,000 m³/day, achieving ammonia compliance often necessitates a tertiary treatment stage (S3, 2025-07). Activated sludge processes are prevalent in high-rise buildings and industry, but their common failure in Indonesia is largely attributed to poor operation, requiring relatively high-skill operators (S3, 2025-07).
An important consideration for tropical climates like Medan, particularly when evaluating existing infrastructure or designing new systems, is methane (CH4) emissions. Life cycle assessments indicate that UASB reactors combined with facultative ponds, such as the configuration used at Pulo Brayan, contribute substantially to climate impact (16.63% from UASB, 49% from facultative pond) and photo-oxidant formation (29.34% from UASB, 31% from facultative pond) due to CH4 production (S4). New designs should prioritize aerobic polishing or MBR systems to mitigate these impacts.
Technology
Typical Capacity Range
Key Advantages for Medan
Considerations/Limitations
Packaged A/O (WSZ Series)
1-80 m³/h (24-1,920 m³/day)
Automated, compact, buried/trailer-mounted, fits diverse commercial/residential needs (S6)
Requires power for aeration, sludge handling
MBR (Membrane Bioreactor)
10-2,000 m³/day
Superior effluent quality (<1 μm), small footprint (60% less), ideal for reuse or strict ammonia (product catalog)
Low sludge production, low operating costs, resilient to fluctuations, SANIMAS communal standard (S3)
Ammonia compliance can be challenging without advanced stages (S3)
RBC (Rotating Biological Contactor)
5-3,000 m³/day
Energy-efficient, robust biological treatment
Ammonia compliance often requires tertiary treatment (S3)
Activated Sludge
High-rise/industrial scale
Proven for high organic loads
Requires skilled operators, prone to failure from poor operation (S3)
Sizing & Configuration for Medan Project Typologies
The WSZ Series packaged A/O sewage treatment plant offers capacities from 1 to 80 m³/h, allowing for flexible sizing to meet the needs of diverse Medan project typologies, from individual buildings to larger residential developments (S6). For a typical single residential block of 50-200 households, a WSZ-10 to WSZ-50 model (10-50 m³/h) is often specified, designed for underground installation to minimize visual impact and maximize landscaping potential, thereby bypassing potential delays with IPAL Cemara connection.
Hotels or hospitals with 200-500 rooms typically require larger capacities, ranging from a WSZ-50 to WSZ-100, or an MBR membrane bioreactor system sized for 200-500 m³/day. For hospitals, meeting the stringent ammonia limit of 10 mg/L is particularly critical due to the nature of their discharge. Industrial campuses with domestic wastewater loads can utilize WSZ-30 to WSZ-80 units, potentially augmented with a DAF pretreatment system (4-300 m³/h) if significant fats, oils, and grease (FOG) are present in the influent (product catalog). For SANIMAS communal systems at the RT/RW scale, anaerobic-aerobic biofilter modules, each designed for 8-10 PE, can be scaled up to capacities of 150 m³/day for hospital applications or 300 m³/day as demonstrated at PT Bogasari Flour Mills (S3, 2025-07). When considering aerated ponds, an LCA-derived sizing check reveals that while they achieve over 70% BOD/COD removal, their operation is heavily dependent on diesel consumption (S4). For new installations, specifying grid-connected electric aerators with Variable Frequency Drives (VFDs) or solar hybrid systems is critical to avoid reliance on diesel generators as baseload, especially where PLN grid reliability is a concern.
Ammonia <10 mg/L compliance is critical for hospital effluent
Industrial Campus (domestic load)
WSZ-30 to WSZ-80 A/O + DAF pretreatment if FOG present
DAF for FOG removal, robust biological treatment for consistent discharge
SANIMAS Communal (RT/RW scale)
Anaerobic-aerobic biofilter modules (8-10 PE each, scalable to 150-300 m³/day)
Low O&M, small sludge production, community-managed
OPEX Drivers in North Sumatra: Diesel, Methane, and Electricity
In North Sumatra, the operational climate impact of aerated ponds is significantly driven by diesel consumption, accounting for 16.97% of the total impact, followed by CO2 emissions (4.95%), N2O biogenic emissions (4.26%), and electricity use (3.04%) (S4). To mitigate this, specifying electric aerators with Variable Frequency Drives (VFDs) is recommended, avoiding diesel generators for baseload power.
UASB reactors, while effective for primary treatment, contribute 16.63% to climate impact and 29.34% to photo-oxidant formation due to methane (CH4) production (S4). Similarly, facultative ponds contribute 49% to climate impact and 31% to photo-oxidant formation, also largely from CH4 (S4). For new installations utilizing anaerobic processes, capturing biogas for boiler fuel or flaring the methane is crucial to reduce environmental footprint. For new builds, replacing facultative ponds with aerobic polishing or MBR systems can significantly reduce CH4 emissions.
Overall, the release of treated effluent represents the largest environmental impact of a wastewater treatment system in Medan, contributing 72% to freshwater ecotoxicity (from CS2) and 80.85% to combined eutrophication (from NH3 and N) (S4). This emphasizes the importance of investing in robust tertiary treatment for ammonia and nitrogen removal to meet P.68/2016 standards and minimize ecological damage. Conversely, anaerobic-aerobic biofilter systems present a favorable operational expenditure profile due to their "relatively low operating costs" and "small/slightly" sludge production, making them suitable for OPEX-constrained communal systems (S3, 2025-07).
Frequently Asked Questions
What packaged plant capacity do I need for a 200-unit Medan apartment block?
For a 200-unit apartment block, assuming a typical design flow of 250 L/person/day and an average of 3-4 persons per unit (600-800 PE total), a WSZ Series packaged A/O sewage treatment plant with a capacity of WSZ-30 (30 m³/h or 720 m³/day) would generally be sufficient. However, always confirm sizing with actual water meter data from similar local developments or project-specific demand calculations.
Can I discharge to Deli River if I meet P.68/2016?
Yes, meeting the P.68/2016 effluent standards allows discharge to receiving waters like the Deli River. However, achieving the stringent ammonia limit of 10 mg/L typically requires dedicated nitrification, which is best accomplished with advanced biological processes like an MBR system or an A/O plant with extended aeration, rather than a basic biofilter alone (S3, 2025-07).
How long to deploy a WSZ packaged plant vs connecting to IPAL Cemara?
Deploying a WSZ Series packaged A/O sewage treatment plant typically involves 8-12 weeks for factory fabrication and an additional 2 weeks for on-site installation and commissioning. In contrast, connecting to IPAL Cemara can involve a much longer timeline, often ranging from 6 to 18 months, due to the need for permit acquisition, extensive pipe extension work, and navigating existing connection queues (S4).
What's the methane risk if I use UASB like Pulo Brayan?
Life cycle assessment (LCA) data shows that Upflow Anaerobic Sludge Blanket (UASB) reactors contribute 29.34% to photo-oxidant formation due to methane (CH4) emissions (S4). To mitigate this risk for new projects, it is recommended to either incorporate an aerobic polishing lagoon after the UASB or specify an MBR membrane bioreactor system, which generally includes aerobic stages that oxidize methane precursors.
Which technology has lowest operator skill requirement?
For minimal operator skill requirements, the anaerobic-aerobic biofilter system is noted for its "easy operation and maintenance" (S3, 2025-07). Similarly, the WSZ Series packaged A/O sewage treatment plant is designed to be "fully automated, with no operator required" (S6).
Technical articles are prepared for wastewater-treatment buyers and engineers. Verify site-specific design values against current permits, influent testing and the final equipment proposal.
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