Chapter 4 Water service system design of songhe park
4.4 Analysis of water demand in the comprehensive utilization service system of
the water source. The method has a small amount of engineering, is easy to construct, and has low cost.
These buildings are closest to the park, with high quality water sources, short pipelines and low costs. Reclaimed water can be used to bring tangible benefits to parks and communities as well as downstream rivers.
4.3.7 Feasibility analysis of rainwater harvesting project
In the collection and utilization of rainwater, the rainwater of the park pool can be mainly collected. It is convenient to collect rainwater from the pool body of the park, and the collection amount is large, and the rainwater can be effectively stored and used.
Although the amount of rainwater collected by underground rainwater pipelines is large, the initial runoff pollution is relatively high, and it is difficult to control the quality of rainwater. At the same time, the rainwater is seasonal, and the monthly collection quantity is unstable, which is difficult to be used as a fixed water source for medium water. Technically, the underground pipeline rainwater needs to be collected through the pipeline and then enters the filtration system to abandon the sewage interception and sedimentation before entering the water storage system. It is necessary to renovate the current rainwater pipeline, which increases the difficulty and cost of the work. The collection of building rainwater is complicated in the construction of the collection system. It is necessary to establish a relatively complicated collection system or to reconstruct the building. The cost is high, and maintenance is required.
Songhe Park should be adapted to local conditions, using economical and simple rainwater harvesting methods suitable for park scales; discarding complex and inefficient methods will help save costs and improve operational efficiency.
4.4 Analysis of water demand in the comprehensive utilization
4.4.1 Analysis of quality requirements for reclaimed water
Songhe Park is located in Shanghai, China, so the water quality standards for all activities are implemented in accordance with China's water quality requirements.
The projects involved in reclaimed water in Songhe Park mainly include plant irrigation, flushing water, cooling spray water, and clean water for teahouse and washroom. Due to the high requirements for drinking water quality, the water quality should meet the water quality standards of the “Sanitary Standard for Drinking Water”
(GB5749-2006). In order to ensure the safety of drinking water for tourists, the water should not be considered as a source of drinking water. The water quality range of other water sources is within the “Classification of Urban Sewage Recycling” (GB/T 18921-2002), and the water quality of the projects involving Zhongshui only needs to meet the various water quality requirements in the standard.
According to the type of water used in the park, the order of water quality demand from high to low is: recreational landscape water (summer cooling spray), waterscape water (viewing pool and fountain), river landscape water (Yangshupu Port), Urban greening miscellaneous water (plant irrigation in the park), flushing of miscellaneous water and cleaning of miscellaneous water (tea house and public restroom).
The summer cooling spray is a new water project after the park poll. The water type is recreational landscape water (human body non-systemic contact water). If water is used as landscape environment water, the water quality should meet the water quality standard of recreational landscape water (waterscape) in “Urban Sewage Recycling-Landscape Water Quality” (GB/T 18921-2002).
The river landscape water is the park that supplies clean water to Yangshupu Port.
The water quality exported to Yangshupu Port shall comply with the water quality standards for ornamental landscape environmental water (river type) of “Urban Sewage Recycling-Landscape Water Quality” (GB/T 18921-2002).
Water for fountains is water for waterscapes, water for water for waterscapes, water quality should meet the water quality of ornamental landscape water (waterscapes) in Urban Wastewater Reuse-Landscape Water Quality (GB/T 18921-2002) standard.
Plant irrigation water belongs to urban greening miscellaneous water. If the reclaimed water is used as urban green water, the water quality should meet the urban greening water quality standard in “Urban Wastewater Recycling-Urban Miscellaneous Water Quality” (GB/T 18920-2002).
Flushing water is used for flushing miscellaneous water. If reclaimed water is used for flushing miscellaneous water, the water quality should meet the water quality standards for flushing water in “Urban Sewage Recycling-Urban Miscellaneous Water Quality” (GB/T 18920-2002).
Clean water is mainly used in the teahouse of the park and the window sill of the public restroom and the cleaning of the floor and the cleaning of the toilet. It belongs to the construction miscellaneous water, and the water quality should be in accordance with the "Urban Sewage Recycling - Urban Miscellaneous Water Quality" (GB/T 18920-2002). The road cleans the water quality standards.
If the reclaimed water service park is used for aquaculture water outside the park, the water quality will have higher requirements. According to the Code for Design of Wastewater Recycling Engineering (GB.T50335-2002), urban sewage recycling can be used in aquaculture, and the water quality should meet the Fishery Water Quality Standard (GB11607-1989), which is equivalent to the environmental quality of surface water. Class III water quality in the Standard (GB3838-2002).
4.4.2 Quantity demand analysis of recycled water
Water demand for flushing water is 3.02m3 /d; On the irrigation water for plants, the water requirement in the irrigation of plants is 2.23m3/d except for rainwater irrigation. Clean water includes window and floor cleaning and toilet cleaning in teahouse and public toilet. Water consumption in teahouse and public toilet is 0.06m3/d and 0.16m3/d respectively. The cooling spray water is mainly used in summer. The water consumption of the spray machine is 0.3m3 per hour, which is calculated as 8 hours per day. The water requirement of the cooling spray machine is 2.4 m3 per day.
River landscape water is used to transport clean recycled water for yangshupu port. The water quantity is the remaining recycled water for clean water every day after meeting the water demand of the above project. There is no fixed quantity requirement, which depends on the water purification capacity.
4.4.3 Summary of reclaimed water demand
Pine crane park comprehensive utilization of water service system demand of reclaimed water at least 12.94 m3 / d (as shown), water quality to meet the surface water environment quality standard "(GB3838-2002) in Ⅲ class water quality standard,
such as table 4.2.
Table 4.2 Statistics of reclaimed water demand in songhe park water service system (Source: author)
Type Water demand
（m3/d）
Water quality requirements
Flushing water 3.02 Water quality standards for flushing water Plant irrigation 2.23 Urban green water quality standard Washing water 0.22 Water quality standards for road cleaning Fountain water 0.14 Water quality standards for ornamental
landscape water (waterscape) Cooling spray (summer
only) 2.4 Water quality standards for recreational
landscape water (waterscape) River landscape water ≥0 Water quality standards for ornamental
landscape water (river courses) Aquaculture water 4.93 Surface water type III water quality standard
Total ≥12.94 Surface water type III water quality standard