Currently Browsing BLOG - Remediation
New Bangalore Lakes Project Video
Check out the new video for the Sherwood Institute’s Bangalore Lakes Restoration Project! The full video can be viewed here.
The project page also has more information about the project’s background and ways that you can get involved to help.
Introduction to Taihu
Lake Taihu (太湖), also called Tai Lake, is the third largest freshwater lake in China. Although it began receiving widespread coverage in the western media after a major algal bloom that covered 1/3 of the lake’s area in 2007, killing fish and disrupting surrounding areas potable water supply, the lake has been experiencing a decline in water quality for the past 20 years. The lake is located on the southern part of the Yangtze in southeastern China and is administered jointly by Shanghai Municipality, Jiangsu Province and Zhejiang Province, serving as a floodwater basin, irrigation supply, drinking water source, aquaculture base and tourist attraction. It is the major source of drinking water for the municipalities of Wuxi, Suzhou and Shanghai. The algal outbreak in 2007, called a “natural disaster” by government officials, caused a noticeble drop in water quality for local residents, who said that they could smell the stench of the algae on their bodies after showering, and were forced to rely on bottled water for drinking.
During the last 20 years, the rapid urbanization of the areas surrounding Taiju, coupled with ineffective management and technical support, have not only caused the eutrophication of the lake, but also its contamination with organic substances and ecological destruction. Now, many doubt the lake’s water quality to ensure safety of the millions who rely upon it as a drinking water source. The water quality of the lake was rated I or II according to China’s National Surface Water Standard up until the 1970s. By the late 1980s the quality had fallen mostly to class III, white in some parts, it reached IV and V. In the late 1990s the lake rated an overall class IV, with approximately one-third of the lake as class V. Lake Tai has become a symbol of water environmental protection, which is a high-priority issue for government at all levels.
Government Five-Year Plans have continued to make Lake Tai an issue of major importance. The Ninth Five-Year Plan (1996-2000) proposed 54 domestic wastewater treatment plants and sewage conduits were planned to be located in the basin. Later however, only 29 plants were completed or partially completed by the end of the period. The Tenth Five-Year Plan (2001-2005), 81 domestic wastewater treatment plants were expected to be built or explanded by 2005. The goal was to be reach over 70% treatment of domestic wastewater. In addition to building more wastewater treatment plants in the Taihu Basin, other measures have also been taken in an attempt to abate the spread of noxious blue-green algal blooms, including releasing algae-eating fish into the lake, physically hauling algae out of the lake, and crackdowns on government corruption in enforcement of effluent standards.
While good intentions obviously exist for the future of Lake Tai, implementation has been difficult and the water quality in the lake has not risen significantly. The main problem of Lake Tai’s pollution issue is the algal blooms. Overgrowth of algae is caused by water that is rich in nutirents (nitrogen and phosphorous), that are usually the limiting factors in algal growth. With nitrogen and phosphorous existing in surface water in excess, algae growth becomes almost limitless, just waiting for the right temporal conditions to cause an extensive bloom. And, when algae goes into respiration conditions at night and when dead algae is digested by microorganisms, the amount of dissolved oxygen in the surfacw water can be virtually depleted, causing fish kills and decrease in biodiversity. According to reports, the major sources of nitrogen and phosphorous in surface water are industrial effluent, domestic wastewater treatment plant effluent, and agriculture. Each type of effluent into surface water has different characteristics; for example, household wastewater is a greater contributor of phosphorous and ammonium (NH4+), while agricultural runoff is a greater contributor of nitrate (NO3-). Below, we can see the contributions of pollution sources Industry (Ind.), Household (Hou.), and Agriculture (Agr.) to the chemical oxygen demand (COD), total nitrogen (TN), and total phosphorous (TP) in Tai Lake. The figure shows that the main contributors of the pollution of Tai Lake have become household discharges and agriculture.
In response to industrial and municipal contributions of nitrogen and phosphorous to surface waters, China’s Five-Year Plans are right to regulate large industries and build more, or retrofit, wastewater treatment facilities (most current wastewater treatment facilities in China do not include tertiary treatment processes that remove nutrients nitrogen and phosphrous from the effluent). Recent banning of phosphorous-containing detergents is another example of effectively reducing the household discharge contribution to the Tai Lake pollution problem.
In my next post, I’ll address agricultural runoff (fertilizers) contribution to the condition of the Tai Lake Basin.
?Source: Wang Q et al. 2006. “Profile: Toward Integrated Environmental Management for Challenges in Water Environmental Protection of Lake Taihu Basin in China” Environmental Management Vol. 37, No. 5, pp 579-588.
Containing the Oil Spill
BP has discontinued their calculations on the amount of oil exiting the well; they have handed this responsibility to the US government. Just yesterday, this taskforce announced that approximately 25,000 to 30,000 barrels of oil are flowing into the Gulf per day. On May 27, BP had estimated that anywhere between 12,000 and 19,000 barrels of oil were exiting the well per day. A month before that, the estimate was 5,000 barrels per day. The first estimate, given several days after the start of the spill, was a “mere” 1,000 barrels per day. 50 days after the oil spill, one could only hope that this number would start to decrease… not increase…
By studying the estimates given by BP, you will see that an almost perfectly (positive) linear relationship exists between the time that has elapsed and the magnitude of the flowrate. In fact, a 95% correlation exists.*
Last week, a containment cap was placed on the well to control the amount of oil exiting into the Gulf. The cap can capture 11,000 barrels per day. However, a large amount of oil is still escaping. The containment cap was designed to funnel the oil to a ship on the surface. Another containment system, which uses the pipes of a previously failed attempt to control the leak, directs more oil to an extra vessel. An additional method is supposed to be installed by the end of this month. This method is expected to withstand hurricane conditions.
The containment cap was lowered onto the failed blowout prevented (BOP) valve system on the seabed. The cap was placed on the lower marine riser package (LMRP) section of the BOP. On June 1, the damaged pipe which removes oil from the well, known as the riser, was cut near where it reaches the seabed. Undersea robots were used to cut through the riser close to the LMRP. After the riser was removed, the cap was lowered onto the LMRP, enabling the leaking oil to be funneled to the ship on the surface.
It is difficult to determine whether the cap is effectively working, mainly due to the lack of consensus regarding the magnitude of the spill. Currently, the total volume of oil that has escaped the well has been estimated to be anywhere between 20 million to 45 million gallons. The flowrate of oil leaving the well has fluctuated greatly and rapidly evolved – from an initial estimate of 1,000 barrels/day to a present estimate of 27,500 barrels/day.
Officials warned BP that cutting the riser may worsen the leak by 20%. Ira Leifer, an expert part of the government taskforce to determine the flowrate, believes that installing the containment cap has made the leak worse. Leifer claimed that the pipe is fluxing more than it previously did. BP has not made any claims as to whether the leak has worsened – they have merely claimed that their engineers are working to make the containment cap as efficient as possible.
Let’s say that cutting the riser did worsen the leak by 20%. The latest estimate by BP (approximately 27, 500 barrels/day) was released after the riser was cut. So according to officials, the exit rate of oil would have been approximately 4,580 barrels/day less, if the riser was not removed. However, the containment cap is projected to capture 11,000 barrels/day. Thus, the additional oil spewing out of the well from installing the containment cap is an additional sacrifice the Gulf of Mexico has to take.
However, we do not know if cutting the riser actually worsened the leak – just like the exit flowrate, there is no consensus on this matter either. BP has not made any statements on the efficacy of the cap. Some officials, including Leifer, believe that the cap worsened the spill by significantly more than 20%. The one thing that is certain about this oil spill is the amount of uncertainty it has produced. Oh, and of course, the amount of damage that it has caused, and will continue to cause.
Oil Pools near Barataria Bay on the Louisiana Coast
A permanent solution to the leak must be discovered soon. BP is digging two relief wells by the end of August. BP hopes that these wells will provide a permanent solution to the oil spill; again, it is uncertain whether they will be truly successful.
The spill has killed 11 humans; many birds and marine animals have either been severely injured or killed. A third of the federal waters of the Gulf remain closed to fishing. Admiral Thad W. Allen of the Coast Guard described the oil spill as “an insidious enemy that’s attacking our shores.” The oil spill has been called the nation’s worst environmental disaster. President Obama has claimed that if Tony Hayward, the chief executive of BP, worked for him, Hayward would have been fired for his poor handling of the oil spill.
* Calculated by plotting the estimated flowrate versus the number of days elapsed since the spill started. The estimates released on May 27th and June 10th were given as ranges. For the purpose of obtaining a correlation, the values were averaged to obtain an approximate flowrate of 15,500 barrels/day and 27,500 barrels/day respectively.
- BLOG (60)
- Agriculture (1)
- Brazil (0)
- China (24)
- Culture (3)
- Current events (6)
- Design (16)
- Development (14)
- Drought (5)
- Education/Career (3)
- Energy (16)
- Events (9)
- India (5)
- Lifestyle (3)
- news (8)
- Parks (2)
- Policy (6)
- Pollution (10)
- Public Spaces (5)
- Remediation (3)
- Resources (1)
- Uncategorized (1)
- Waste Management (3)
- Water Distribution (2)
- Water management (17)
- Water Resources (31)
- Water Treatment (6)
- Wetlands (3)
- CHAPTER 10 (6)
- Featured (1)
- INTERNAL RESEARCH (0)
- PROJECTS (0)
- Sherwood Event @ Greenbuild 2012
- SSIR – Bangalore Lakes by Michel St. Pierre
- Michael Thorton: Skoll Centre for Social Entrepreneurship
- Featured Box
- New Bangalore Lakes Project Video
- Opinions about the development of the environmental protection industry during the 12th FYP period
- 12th China International Environmental Protection Exhibition and Conference
- China’s Five Year Plans: Importance and Implementation
- My Research at Tsinghua University
- Old Summer Palace: Example of Chinese Public Involvement in Environmental Issues