Domestic Wastewater Treatment – Above-Ground Underground Types

Above-Ground Systems – Core Advantages

Extremely convenient maintenance and inspection – All equipment is fully exposed above ground, allowing for easy routine inspection, debris removal, part replacement, and sludge discharge without excavation. Faults are quickly located and repairs are highly efficient.

Fast installation and low cost – No large-scale earthworks required. Simple foundation preparation, followed by crane placement and utility hookups (water and electricity), resulting in a short construction period and low initial investment.

Strong environmental adaptability – Not restricted by groundwater level, geological conditions, or frost line. Suitable for mountainous areas, high-water-table regions, and cold climates.

Flexible expansion and relocation – Modular and skid-mounted design allows for parallel expansion for increased capacity, as well as integral crane lifting for relocation.

Good ventilation and easy odor control – Open layout facilitates natural odor dispersion, while optional sealed covers are available. No risk of musty or trapped odors as found in underground installations.

Easy temperature management – Optional insulation, heating, or shading can be added to ensure stable winter operation.

Underground Systems – Core Advantages

Small footprint, high land-use efficiency – The entire system is installed below grade, allowing the surface to be used for landscaping, paving, parking, or green space. Ideal for land-constrained projects such as residential communities, hospitals, scenic areas, and B&Bs.

Stable underground temperature for consistent biochemical performance and freeze protection – The surrounding soil provides natural thermal insulation, maintaining a stable temperature in winter. No additional equipment insulation is required in northern regions, and microorganisms are protected from freezing, ensuring superior effluent quality during cold months compared to above-ground systems.

Low noise and minimal odor – Fans and pumps are buried underground, with soil absorbing sound and vibration. The enclosed tank with optional soil-based odor control effectively minimizes nuisance odors and preserves visual aesthetics.

Fully automatic unattended operation – Integrated A/O (anaerobic/aerobic) or biological contact oxidation process with built-in level control, intermittent aeration, automatic reflux, and fault alarms. Daily operation only requires periodic inspection and sludge extraction (every 3–6 months).

High degree of integration – Integrates screening, regulation, anaerobic, aerobic, secondary sedimentation, disinfection, and sludge storage into a single pre-fabricated unit. On-site work is limited to pit excavation, positioning the unit, and connecting inlet/outlet pipes and power supply.

Long service life – Mainstream materials: FRP (fiberglass-reinforced plastic) or heavy-duty epoxy-coated carbon steel, offering excellent corrosion resistance to wastewater. Normal service life: 15–25 years.