A secondary seawater desalination system priced at 5.165 yuan/ton? The minimum cost can be controlled at 3 yuan

Project Introduction

This project is a seawater desalination facility in Zhoushan. The process employs "coagulation-sedimentation + sand filtration + seawater reverse osmosis (SWRO) + partial second-stage reverse osmosis," with a system capacity of 250 m³/day.

1.Project Overview

Project Name	Zhoushan 250 TPD Seawater Desalination Project
Project Type	Coagulation-Sedimentation + Sand Filtration + Seawater Reverse Osmosis + Partial Second-Stage Reverse Osmosis (Seawater Desalination)
Project Location	Zhoushan, Zhejiang, China
Client/Owner	Local client
Contractor/Supplier	Anhui Cooperate Ltd.
Project Start Date	October 2025
Project Completion/Handover Date	February 2026
Project Status	Handed over

2.Project Background and Requirements

Islands face a shortage of freshwater resources, and the supply of drinking water for residents lacks security.

2.1 Water source conditions

Parameter	unit	reference value
Water source type		surface seawater
PH		6-9
SS(mg/L）	mg/L	＜300
Inlet TDS (total dissolved solids)	mg/L	＜ 30000
Conductivity（μs/cm）	μs/cm	＜60000
Inlet water temperature range	° C	15-35 ° C

3. Technical Solution - Process Flow

3.1 Overview of Process Route

3.2 System Specifications and Design (Partial)

Serial number	name	model/specification
One	Preprocessing equipment (sedimentation)	Design output 27m3/h
1	coagulation sedimentation tank	Processing capacity of 27m3/h, size approximately 2.5 × 7 × 3.0m, integrated equipment for coagulation reaction, sedimentation, and production water tank
2	PAC dosing equipment	1m3 PE dosing box with 0.55kW mixer and 50L/h PVC dosing pump
3	PAM dosing equipment	1m3 PE dosing box with 0.55kW mixer and 50L/h PVC dosing pump
4	Multi medium inlet pump	AS32-20, Q=27m3/h，H=40m, N=5.5kW
5	Multi medium tank	Diameter of 2000mm
Two	SWRO equipment	Design output 15.5m³/h
1	Energy recovery device	IPX-31, Q=15m³/h，N=1.5kW
2	seawater desalination membrane	8-inch seawater desalination membrane*21
Three	Secondary RO equipment	Design output 6.5m³/h
1	RO membrane	8-inch RO membrane 8040*14
Four	Mineral addition system
1	Mineral addition tank	800mm diameter, containing mineral filter material
Five	dosing system
1	Various dosing systems	100L PE dosing box with 0.37kW mixer, 5L/h PVC dosing pump, PP floating ball level switch
Six	Cleaning system
1	clean the water tank	V=2000L， Cone bottom water tank
Seven	Electronic control system and other supporting facilities
1	omit	omit
Eight	Water output system
1	Production water tank	2T， Cone bottom water tank

4.Expected system effects

4.1Design water production effect

Number	testing item	unit	value
1	PH		6.5-8.5
2	Turbidity	NTU	＜1
3	Conductivity（μs/cm）	μs/cm	＜500
4	SS(mg/L）		Not Detected
5	chloride	mg/L	＜250
6	sulfate	mg/L	＜250
7	TDS	mg/L	＜300
8	Total hardness (calculated as CaCO3)	mg/L	＜450
9	Recovery rate		46.3%

4.2Design system operating costs

name	Unit price	Yuan/ton cost
Pharmaceutical expenses	/	0.483
electricity bill	0.7 yuan/degree	4.27
Consumables Cost	/	0.412
Direct operating costs		5.165

This case is designed as a secondary seawater desalination system. If the environmental conditions are stable, a primary seawater desalination system can be designed with a minimum cost of 3 yuan

Explanation

The operating cost is based on the inflow index within the scope of this technical solution design.
The market prices of pharmaceuticals vary, and the dosage may also differ under different water quality conditions, thus having a certain range of variation.
There is a close relationship between membrane depreciation and the standardization of operators, that is, proper maintenance and upkeep result in longer membrane lifespan; On the contrary, the lifespan of the membrane is short. This is only based on the experience of similar projects as a reference

5.After-sales service

Supplier proposes after-sales service commitment:
(1) During the warranty period after equipment acceptance, if there is a malfunction in the equipment within the supply scope of the system, a clear response will be given within 12 hours through remote analysis and diagnosis. If the problem can be solved remotely, remote guidance will be provided. If the problem cannot be solved remotely, the equipment will arrive at the site within the agreed time. Free replacement of parts with quality issues.
(2) When system equipment malfunctions, regardless of the reason, the principle of ensuring normal production operation should be followed first to eliminate the fault, and then analyze the specific cause of the fault and clarify responsibility.
(3) After the warranty period expires, spare parts will be provided at a discounted price.
(4) Provide at least one phone visit per month to understand the operation of the system and provide necessary consulting services.
(5) Before the replacement of spare parts within the scope of supply, our company promptly notifies users so that they can stock up in advance.

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