Sewerage Systems Office

In order to comply with the more restricted effluent standards announced in 1998.1.1 by the Environmental Protection Agency, Executive Yuan, the Dihua Sewage Treatment Plant History stopped operations in 1998.4.7 for upgrading to a Class-2 process, the upgrading project mainly comprised of civil works, treatment systems and landscaping. The entire project was completed in November 2006 and formal operations started in February 2007. Sludge reducing equipment was completed in 2014.

Sewage is treated by deep chamber staged aeration Class-2 biological treatment followed by disinfection before discharging into the Tamsui River; sludge is treated by thickening, anaerobic digestion and dehydration and then hauled by an entrusted legal removal service provider to the EPD’s incinerator in Taipei City for incineration.

1. Design Capacity: Daily Average sewage treatment 500,000CMD
2. Design Quality:
   • Intake Sewage: BOD5 = 180mg/L, SS = 180mg/L;
   • Effluent Quality: BOD5≦20mg/L, SS≦20mg/L.
3. Recycled Water for re-use: Design capacity: 10,000CMD

1. After entering the Dihua Sewage Treatment Plant, large solids in the diverted sewage are first removed by a Fine Bar Screen, most precipitable suspended solids are then removed by a Primary Clarifier. Effluent from the Primary Clarifier then enters the aeration chamber and secondary clarifier for removing organics. Sodium hypochlorite is finally added to remove germs and effluent before it is discharged into Tamsui River. A 10,000CMD portion of the effluent is further treated by sand filter for recycled use.
2. As for the manure, together with thickened sludges from primary and secondary clarifiers, it is treated by anaerobic digestion and dehydration to from sludge cakes. The cakes will be further used for multiple purposes after completion of the plant’s sludge reduction project, such as for incineration, brick making, road foundation material, cement additive, etc.
3. Gas produced in the Anaerobic Digest Chamber is recycled for re-use; in addition to being used for stirring the digest chamber itself and fueling the boiler for maintaining temperature of the chamber, the rest is used as heating energy for the sludge dryer system.

1. The plant’s main treatment unit is a 210m x 250m installation in a 17m depth under the ground, daily capacity 500,000CMD, the biggest Class-2 sewage treatment facility in Taiwan.
2. The main unit includes: intake preliminary treatment, primary clarifier, deep-trough aerator, secondary clarifier, disinfection chamber, and effluent pumping station. All of them are enclosed semi-underground structures. Additional facilities include a deodorizing system and noise insulation for minimizing negative effects to the surroundings.
3. Both the primary and secondary clarifiers adopt a double layer design which is first seen in Taiwan, enabling higher treatment capacity in a limited floor area. Additionally, the biotreatment of deep trough staged aerator is also the initial application in Taiwan; besides general biotreatment, it also provides nitrogen removal.
4. The plant is equipped with Class-3 recycling facility (automatic backwash sand filter) for supplying water for washdowns and irrigation use within the plant and horticulture use of the public.
5. The top area of the main treatment unit has a coverage of 4.6 hectares, i.e., 13,900ping, providing versatile leisure facilities such as children’s playground, skating rink, lawn activity area, basketball court, tennis court, softball field, parking lot and public arts for public use.

After its upgrading to a Class-2 plant, the Dihua Sewage Treatment Plant not only improved its effluent quality that meets stricter effluent standards, but also significantly lowered the risks of the enlarge system. Furthermore, the integral design made optimum use of the land: a 500,000CMD sewage treatment plant is built on the original land, a nearly 100% increase to the original capacity, plus with a leisure park installation on the top, providing facilities for leisure activities for the citizens.