Wastewater Treatment Process

The objective of municipal wastewater treatment is to treat water collected from households and industries such that the wastewater meets the quality standards specified by the government before discharge back into the rivers or further treated for reclamation. The typical steps of a wastewater treatment process are collection, primary sedimentation, biological treatment, secondary sedimentation, disinfection and discharge.

(1) Collection
The wastewater of a city is channelled from the various sewage water collection points through a pipeline network system to the treatment plant. In the treatment plant, the wastewater first passes through bar screens whereby large objects that could damage or interfere with the process and equipment are removed. The wastewater then enters grit removal tanks, whereby heavy inorganics such as sand, gravel and rocks, collectively known as grit is allowed to settle to the bottom of the tank and removed.

(2) Primary sedimentation



The wastewater is allowed to pass slowly through large tanks known as primary clarifiers, where suspended solids and other non-soluble particles can settle and floating material such as grease
and oils can rise to the surface and be skimmed off. The main purpose of this stage is to produce a generally homogeneous liquid capable of being treated biologically. Primary clarifiers are usually equipped with mechanically driven scrapers that continually drive the collected sludge towards a hopper in the base of the tank from where it can be pumped for further sludge treatment.
(3) Biological treatment
The wastewater flows into large aeration basins, where it is mixed with air to aid the growth of
micro-organisms that naturally live in wastewater. The micro-organisms, called “activated sludge”clean the wastewater by digesting organic materials and other soluble contaminants. Wastewater remains in the aeration basins for a few hours to allow time for the micro-organisms to grow and consume the bacteria.
(4) Secondary sedimentation
The wastewater is then pumped into secondary clarifiers, where the “activated sludge” is allowed to settle out of the water.
(5) Disinfection
The purpose of disinfection in the treatment of wastewater is to substantially reduce the number of micro-organisms in the water and to kill any remaining pathogenic (disease producing organisms before the water is discharged back into the environment. Common methods of disinfection include adding chlorine or using ultraviolet light.
(6) Discharge
After disinfection, the treated water should be able to satisfy the national standard of sewage
discharge stipulated by the PRC government and can be discharged to the river directly or undergo more advance treatment process for reclamation purposes.

Water Supply Process - Purify raw water from surface or underground water sources

The objective of a municipal water supply plant is to treat and purify raw water drawn from approved surface or underground water sources to obtain potable water that complies with purity standards set by the government and distribute the potable water to households and industries for their use. ( The water drawn is not wastewater but raw water) There are various techniques used in the industry for the treatment and purification of raw water but generally a water supply process will have the following steps: collection, mixing and flocculation, sedimentation, filtration and disinfection.

(1) Collection
Raw water is obtained from either surface water sources such as lakes and rivers or underground water sources. Surface water sources have to be approved by the government which set stringent criteria such as COD content, proximity to heavy industries, etc.

(2) Mixing and flocculation
The main impurities present in raw water are floating solids, colloids and soluble microscopic
particles. The mixing and flocculation process involves the addition of coagulation chemical agents such as bitter salt, benzotrichloride and aluminium sulphate. These coagulation agents will react with the colloids causing them to stick together to form clumps which can then be easily removed through the sedimentation process.




(3) Sedimentation
Following the mixing and flocculation process, the raw water will be pumped into large water tanks known as clarifiers whereby non-soluble particles such as sand, mud particles and the clumps will form a “sludge blanket”. As these non-soluble particles and solid clumps are heavier than water, the blanket will sink to the bottom and as it does, the blanket works like a finely-meshed net to catch other smaller particles. The water at the top of the tank, now free of solids, overflows to the gutter-like spokes at the top of the tanks.

(4) Filtration
Water is then transferred into the filtration basins whereby soluble microscopic particles will be
removed. At the bottom of each filtration basin are layers of coarse sand, fine sand and activated carbon. As the water seeps down through these layers of sand and coal, tiny particles as small as
one micron are left behind. The activated carbon also has the ability to remove tiny particles and also chemical compounds that affect the water’s taste and odor.

(5) Disinfection
The filtered water then goes through a final disinfection whereby chlorine and chloramine are
added to kill any bacteria or viruses that may be present in the pipes from the plant to the final
user. Water is also checked for purity level for consumption before it is pumped out for residential and industrial use.

Current Trends In The China Water Market

Innovation of technologies
There is increasing awareness of the need for adoption of new technologies and methods by the local companies and government bodies to increase the efficiency in the industry. Chinese companies in this industry have traditionally been lagging behind their multinational counterparts in terms of technology innovation and this has limited their ability to compete in the larger projects.

Increasing number of players in the industry
The Chinese water market has entered the growing stage, which is reflected by the rising number of companies in the industry. As a result of the privatisation policy of public municipal infrastructure and the high return on investment, many companies including multinationals have started to penetrate the market. The presence of foreign investment is now felt in all facets of the water supply and wastewater treatment industry in China from direct construction and operation of treatment plants through BOT to joint ventures and wholly owned subsidiaries. Several large established multinationals such as Veolia, Suez and RWE Thames have all established their presence in the PRC market.

Move towards privatisation
The water supply and wastewater treatment market in China is currently in the process of transition from a predominantly state-owned sector to a more market base sector through the rationalisation of water tariffs and the opening up of the sector to private and foreign investors. Outsourced management such as BOT and TOT are becoming popular models in the industry. Privatisation is considered to be the most efficient way to address the fund shortage for investment in the development of municipal water supply and wastewater treatment projects.

Drivers Of The China Water Market

Government investment in the industry
11th Five Year Plan
In the recent 11th Five Year Plan (2006 – 2010) that was adopted by the State Council in September 2007, the PRC government has committed to investing 1.35% of annual GDP for the next three years on environmental protection. According to Mr Zou Shoumin, director of the Chinese Academy for Environmental Planning who took part in drafting the plan, the majority of the spending will be used for treating water pollution. He estimated the PRC government spending on treating water pollution at approximately RMB640 billion (US$85.33 billion). In the 11th Five Year Plan, the PRC government also set several qualitative targets such as:
(i) reduce the chemical oxygen demand (“COD”) (an industrial measure of the quality of wastewater
discharge) in discharged wastewater by 10% by the end of 2010;
(ii) increase urban wastewater treatment rate to 70%;
(iii) 80% of portable water resources to meet quality standards; and
(iv) at least 43% of the water in the seven major rivers to be in the Grade I-III categories and water in the “inferior to Grade V” category to be lower than 22%.

Foreign investment in the industry
Though the government provides the bulk of financing for environmental projects, China has been very successful in attracting foreign investment in this sector. This includes private financing, multilateral/international loans and multilateral grants. China has long been the largest recipient of environmental assistance from the World Bank, the ADB, the Global Environmental Facility as well as considerable financial and human capital from international NGOs. According to the 2006 Statistic Bulletin on China Water Activities published by the MWRC, the total planned investment of fixed assets in the water sector in China was RMB93.27 billion, of which approximately 80% was from the central and local government agencies.
Foreign investment in the industry will also bring with them advanced technology and know-how which will in turn improve the efficiency of the municipal water and wastewater treatment industry in China.

Government policies and incentives Besides making direct investments in this sector, the PRC government also put in place several policies to speed up the development in this industry such as the “Circular on Accelerating the Industrialisation of Municipal Wastewater and Waste Treatment” and “Decisions on Accelerating the Market Conversion of Municipal Public Utilities”. The first policy focuses on introducing market mechanism into the construction of new municipal wastewater treatment facilities such as BOT/TOT or public-private partnership (“PPP”)
mechanisms. The second policy focuses on efficient private-sector operators bringing managerial skills and technology to China to acquire water assets and reap rewards from improving the efficiency of the acquired assets. One of the ways for the government to attract private-sector investment and to help curb water loss is via steady water tariff increases. The government has also raised the guidance on the allowed rate of return from 6% to 12% on net assets.

There are also tax deductions for enterprises using certain industrial waste products as raw material and value-added tax relief for import of pollution prevention and control products (to accelerate foreign investment and promote the import of advanced technologies and equipments). Other than this, the PRC government has also introduced strict measures aimed at tackling the water pollution in the country’s ailing rivers and lakes. Measures introduced include tougher emission standards for industries, increased monitoring of heavy polluting industries and heavy penalties imposed on offenders.

Increasing alignment of development with environmental objectives
The Chinese economy is booming with high rates of investment but increasing attention is being given to the urgent nature of environment problems both by local and international political and social groups. This rise in general environmental awareness as well as international events such as the Beijing Olympics in 2008 and World Expo in 2010 to be held in China are expected to serve as catalysts for the development of the environmental industry.

Overview of the China Water Market

Sources of water in China
China has the fourth largest water resources in the world with total water resources of approximately 2,533 billion m3 by the end of 2006. Despite this, China’s per capita water resource is only one quarter of the world average.
The distribution of water resource in China is characterised by severe regional and seasonal disparity. In Northern China, the per capita availability of water is only one fifth that of Southern China despite having 65% of the country’s cultivated area and almost half of the country’s population and GDP. Southern China, though in possession of greater water resources is grappling with extensive water pollution. Precipitation is also uneven throughout the year with more than 50% of the annual precipitation concentrated in the three months between July to September giving rise to frequent flood and waterlogging disasters. As a result of these disparities, China continues to face annual water shortages to the tune of 40 billion m3 and severe repercussions on its social and economic development.

Consumption of water in China
Total consumption of water in China by the end of 2006 was approximately 580 billion m3 or per capita consumption of 442 m3. Water consumption is expected to increase with rising industrialisation, urbanisation and standard of living and is expected to reach levels of 700 billion m3 to 800 billion m3 in 2030 if no effective water saving measures are introduced bringing it close to the maximum of usable water resources in China, which is estimated at around 800 billion m3 to 900 billion m3 in 2030.

The largest user of water in China is still the agriculture sector accounting for 63.2% of total consumption in 2006. However the agriculture sector’s proportion of total water consumption has been decreasing since 2000 due to increases in the industry and residential water sectors.

Quality of water supply in China
There are seven major water bodies in China; namely Yangtze River, Pearl River, Yellow River, Huai River, Hai River, Liao River and Songhua River. Although the water quality in these seven major water bodies had been gradually improving over the years, the water quality level is still far from ideal. As of 2006, less than half of the total water supply is categorised as Grade I-III (suitable for consumption) while 26% of the water is categorised as “inferior to Grade V”. Amongst them, Pearl River and Yangtze River enjoyed good water quality while the Songhua River, Yellow River and Huai River were subject to intermediate pollution. The Liao River and Hai River were considered heavily polluted. The main pollutants are permanganate index, ammonia nitrogen, and petroleum.

Extensive economic growth, low utilisation efficiency and high pollutants discharge has caused severe water pollution in China, which makes clean water resources increasingly scarce. According to a survey conducted by the MWRC on drinking ground water quality of 118 Chinese cities in 2005, close to two thirds of the water in these cities was severely polluted, compared to only 3% that was nearly clean. A burgeoning population and increased rates of urbanisation have also contributed to the problem and in the future these factors along with improving standards of living are expected to increase the intensity of the problem.

Water supply and wastewater treatment market in China
There is acute water pollution in China, particularly groundwater contamination and pollution of coastal seas. About 40% of river water is ranked as poor by domestic standards and between 80%-90% of untreated water still flows back into the rivers and lakes. The percentage of the total population in China connected to the water network and with access to improved sanitation is well below world average. In 2005, the total wastewater discharge in China was approximately 52.5 billion tonnes and is growing at a rate of 5% per year.

The water supply and wastewater management sector has been a priority for the Chinese environmental authorities in recent years. This is evident from the fact that out of the total environmental investment in pollution treatment projects in China since 1999, the proportion on water supply and wastewater treatment projects has been the largest and in the range of 40%-50%. The total government investment completed in 2005 on wastewater treatment was approximately RMB13.4 billion. However, despite the large investment made in this area, one third of the cities in China are still without wastewater treatment plants and with the increasing rate of industrialisation and urbanisation, the need for greater investment in this sector will continue to remain a priority.

Growing water consumption and increasingly severe water shortages in China have prompted both the government and industries to pay closer attention to wastewater reclamation. Technology advances have made water reclamation feasible and with the lower price of reused water as compared to water from a municipal water supply plant, ratio of industrial reused water usage is expected to increase.

According to the MCC, the total investment requirements of the water supply and wastewater treatment industry in China is estimated at RMB1,000 billion from 2006-2010, which will exceed the estimated government spending in this sector. The shortfall is expected to come from private capital investments. The following shows the distribution of water investment requirements in China from 2006-2010: