Tuesday, May 11, 2010


Biosolids (treated sludge) are nutrient-rich organic materials that are created through the treatment of domestic wastewater generated from sewage treatment facilities. At the facility, the sewage goes through physical, chemical and biological processes to remove the solids and separate water. If necessary, the solids get treated with lime to raise the pH level to eliminate odor problems. The wastewater treatment processes sanitize wastewater solids to control pathogens and other organisms that can cause diseases. In Toronto, biosolids are treated at the Ashbridges Bay Treatment Plant (77%) and the Highland Creek Treatment Plant (23%) and generates about 195,000 tonnes every year (about 72% of this is water). Biosolids are used as sustainable agricultural fertilizer to improve and maintain productive soils and to stimulate plant growth. They have been used by farmers and gardeners to promote the growth of agricultural crops, fertilize gardens and parks, and reclaim mining sites.

Wastewater Treatment

Source: http://www.omafra.gov.on.ca/english/nm/nasm/info/brochure.htm#1

In this picture, municipal wastewater enters the treatment plant in which it undergoes primary treatment where heavier solids settle out. These heavier solids are sent to either an aerobic or anaerobic digester where the organic solids are converted by micro-organisms into a stable form. When that process has been completed, biosolids get transported to a land application site or a storage facility.

The cleaner wastewater resulting from primary treatment undergoes secondary treatment where chemicals are added to precipitate out phosphorus in chemical compounds, and promote the coagulation or aggregation of other solids that still remain in wastewater. The water from secondary treatment gets subjected to chlorination (disinfection) and then gets discharged to the surface water outlet.

Quality of Biosolids

Nutrients and Phosphorus in Biosolids

Biosolids contain large amount of nutrients such as nitrogen and phosphorous, and contain trace elements such as sulfur, magnesium, calcium, copper, and zinc. Nutrients are important for crop production and growth. Plants obtain nutrients from the soil and return them to the land when it dies and decays. This natural cycle is interrupted when agricultural harvesting removes part or all of the plant from the land. Farmers can replace nutrients in the soil with biosolids.

Organic Matter

Biosolids are mainly composed of organic matter. Application to land can help restore organic matter that is removed from the soil by tilling and harvesting. The organic matter in biosolids makes soils more absorbent, improves the circulation of air and water and provides space for plant roots. This results in better plant growth, greater resistance to unfavourable weather conditions and better soil manageability. Most cultivated soils in Ontario contain less desirable amounts of organic matter but when its added with biosolids, organic matter gets added.

Metals in Biosolids

Biosolids contain small quantities of metals such as iron, manganese, zinc, copper, boron, molybdenum and cobalt. This is linked to insoluble inorganic and organic components. As a result, metals added to soil are stable and will not easily migrate into surrounding ground and surface water. Plant uptake of metals in the soil is small. Field crops remove less than 0.4 kg/ hectare per year of metals from the soil. Uptake of metals added to the soil will vary depending upon the crop grown, soil pH, soil organic matter, clay content, soil aeration and the concentrations of nutrients and metals originally in the soil.

Uses of Biosolids

Biosolids are used in different areas: agriculture, mine reclamation, land scraping and forestry.


Biosolids are used to fertilize fields for raising crops. Agricultural use of biosolids has made significant improvements in crop growth and yield. It reduces the farmer’s production costs and replenishes the organic matter that has been depleted from the soil. The organic matter increases the soil’s ability to absorb and store moisture.

Mine Reclamation

Biosolids have been used at mine sites to establish sustainable vegetation. The organic matter, inorganic matrix and nutrients in the biosolids reduce the bioavailability of toxic substances that are found in mine soils and they also regenerate the soil layer. This regeneration is very important for reclaiming abandoned mine sites with little or no topsoil.

Source: http://www.rdn.bc.ca/cms/wpimages/wpID1140imgID1072.jpg


Biosolids composted with sawdust, wood chips, yard clippings, or crop residues makes excellent mulches and topsoils for horticultural and landscaping purposes. Many professional landscapers use composted biosolids for landscaping new homes and businesses. Home gardeners also find composted biosolids to be an excellent addition to planting gardens.


Biosolids have been found to promote rapid timber growth that is allowing quicker and more efficient harvest of an important natural resource.

Source: http://cfc.cfans.umn.edu/research/images/biosolids3.JPG

Toronto Biosolids

Throughout the world, biosolids are returned to the environment in a variety of ways. Although the city of Toronto continually pursues beneficial reuse options, we currently use a combination of methods to manage biosolids. The table below shows where our biosolids went in 2008:

2008 Biosolids Reuse/Disposal Methods Management Percentage
Landfill 41%
Incineration at Highland Creek 23%
Land Application 11%
Pelletization 16%
Alkaline Stabilization 5%
Site Remediation 4%

Source: http://www.toronto.ca/water/biosolids/index.htm

Advantages of Biosolids

  • Biosolids are rich in both organic matter and essential plant nutrients
  • It can be utilized as a soil amendment and fertilizer.
  • Biosolids act as a soil amendment through the contribution of organic matter.
  • Increased organic matter improves soil physical properties including moisture holding capacity, aggregation, porosity and tilth.
  • A reduction in fertilizer costs
  • Biosolids serve as a fertilizer by providing essential micro (e.g. zinc, copper and iron) and macronutrients (e.g. nitrogen, phosphorus and potassium).

Disadvantages of Biosolids

  • Biosolids can cause odor problems especially in residential areas
  • Some metals in biosolids can create problems with human health and plant growth.
  • The soil can have an excess of nutrients.
  • Biosolids may have pathogens, which can cause diseases


Biosolids can improve and maintain productive soils and stimulate plant growth so it has been used by farmers and gardeners widely. It contains lots of nutrients such as nitrogen and phosphorous, and trace elements such as sulfur, magnesium, calcium, copper, and zinc. Biosolids can be used in a variety of areas such as agriculture, mine reclamation, land scraping, and forestry. It can improve crop growth and soil productivity in agriculture and landscaping. It can establish suitable vegetation in mine reclamation and promote timber growth in forestry.
Increased organic matter improves soil physical properties including moisture holding capacity, aggregation, porosity and tilth. Improvement of these properties facilitates transport of air, water and nutrients throughout the soil, benefiting the establishment and growth of vegetation. Biosolids serve as a fertilizer by providing essential micro (e.g. zinc, copper and iron) and macronutrients (e.g. nitrogen, phosphorus and potassium) that increase vegetation growth and productivity. The stabilized biosolids provide a slow release source of nutrients that can be utilized by plants for several years following application. Farmers and gardeners can save money by using biosolids to fertilize.

On the other hand, there are disadvantages in using biosolids. Biosolids can cause odor problems especially in residential areas. It may contain some pathogens that can cause disease. Some metals present in biosolids can create problems with human health and plant growth. For example, arsenic (a metal present in biosolids) can cause health problems in a child eating a soil mixed with biosolids. Nickel (another metal present in biosolids) can deteriorate plant growth. The soil can only store a certain amount of nutrients so the excess moves to surface water or groundwater. That can cause high nitrate concentrations in forage that can kill animals consuming the forage.

When comparing the advantages and disadvantages of biosolids, I find that there are more advantages than disadvantages. For successful utilization of biosolids, we need a combination of proper application methods, best management practices, and nutrient management planning. When biosolids are applied to land according to regulatory requirements, risks to environment and human health are negligible. Therefore, I believe that it is beneficial to use biosolids to maintain plant growth and soil productivity.


Sunday, May 2, 2010

Advances in Medical Technology

Medical technology is an important component of medical health care and can provide significant benefits to patients. It can help us to understand internal body systems (digestive, circulatory or respiratory), diagnosis, and treatment. It includes diagnostic devices (e.g. defibrillator, MRI, CAT scans), and treatment procedures (e.g. joint replacements, therapies, surgeries). Medical technology has made a significant contribution to the development of fast, precise and gentle diagnostic procedures and new therapies. It makes the process of medical practice efficient for people in the medical field and also for the patients. There are different types of medical technology that can contribute to the understanding of all internal systems such as X-rays, MRI, CT scans, etc and some help us to understand a particular type of internal system (e.g. Defibrillator is used for the circulatory system)

In the beginning of the 20th century, medical technology became revolutionized using tools such as stethoscopes, microscopes, thermometers and X-ray machines. With these medical devices, doctors are able to see and hear patient’s organs such as lungs and heart.

Medical technology (Diagnostic devices):

  • Computerized Axial Tomography (CAT): In the present time, scientists have combined X-ray technology with computer technology to get a better view of the body organs. In the computerized axial tomography (CAT) scan procedure, many X-rays are taken from many angles and reassembled to make three-dimensional images. CAT scans provide information of different structures and these images get stored in the computer with their location and angle. CAT scans can distinguish between gases, liquids, and solid tissues are useful for detecting blood clots in the head.
Source: http://www.clarian.org/ADAM/doc/graphics/images/en/19237.jpg

Other diagnostic devices include:

  • X-rays: It uses electromagnetic radiation to make images. The image is recorded on a film, called a radiograph. The parts of the body appear light or dark because of different rates that tissues absorb the X-rays. Calcium in bones absorbs X-rays the most, so bones look white on the radiograph. Fat and other soft tissues absorb less, and look gray. Air absorbs least, so lungs look black. Health care professionals use them to look for broken bones, problems in the lungs and abdomen, cavities in teeth and many other problems. For example, mammograms use X-rays to look for tumors or suspicious areas in the breasts. X-ray technology.
  • Blood tests: A laboratory analysis performed on a blood sample that is usually extracted in the vein from an arm using a needle. Blood tests are used to determine physiological and biochemical states, such as disease, mineral content, drug effectiveness, and organ function. The blood then gets stored in a test tube.
  • Magnetic Resonance Imaging (MRI): It uses the spinning motions of the atomic nuclei to produce a map of the internal structure of human body tissue and to reveal how organs are functioning.
  • Nuclear imaging: It uses radionuclides to view organs and tissues of the body. The radionuclides that they use are the nucleii of unstable atoms that emits rays of energy. It gets injected into the body to collect in the target organs. Different radionuclides are used to identify different organs (ex. A thallium isotope can be used to identify heart imaging.
  • Stethoscope: It is used to hear sounds within the body. Doctors use it to listen to sounds from the heart, lungs, intestinal tract, and blood flow. Therefore, they are able to detect normal and abnormal cardiac, respiratory, arterial, venous, intestinal, uterine, and fetal sounds.
  • Defibrillator: It is used to detect heart rates that are too fast or too slow and correct them by using an electrical current. It can maintain or correct the rhythm of the heart.

Medical technology has helped us to provide new treatments and therapies with improved success of medical care to patients.

  • Laser Eye Surgery: It is an advanced medical technology that corrects vision problems. In this surgical procedure, light rays are bent or refracted by the cornea so that they are directed on the retina. (The retina is a layer of cells that senses light). There are two procedures of eye surgery. Each reshapes the cornea, the curved front surface of the eye. In both cases a “cold” laser is used, which prevents damage to the surrounding eye tissue. And in each case the eye gets healed by itself. During the first kind of procedure, the surgeon uses a laser beam to reshape the surface of the cornea to correct the vision. During the second kind of procedure, the surgeon cuts a flap in the cornea, lifts it, and then uses a laser to remove calculated amounts of tissue from inside the cornea, and then closes the flap.
Source: http://www.torontolasiksurgery.com/wp-content/uploads/2008/09/laser-eye-surgery-chart.jpg
  • Chemotherapy: In this treatment, drugs are used to destroy cancer cells. Chemotherapy is the most popular cancer treatment worldwide. It stops or slows down the growth of cancer cells. It is applied to treat leukemia (a kind of cancer of the bone marrow which causes uncontrollable and abnormal growth of white blood cells) and lymphoma (cancer in lymph or nodes).The functions of chemotherapy are that it cures and controls cancer, and eases cancer symptoms. Cancer cells can no longer grow back when they are destroyed by chemotherapy. Source: http://pharmaknow.com/wp-content/uploads/2008/05/chemo.jpg
  • Radiation Therapy: It is the medical use of ionizing radiation as part of cancer treatment to destroy malignant cells. It is one of the several treatments that can be used to treat cancer by itself or in a combination of other forms of treatment such as surgery or chemotherapy. Radiation therapy is also known as radiotherapy.

Source: http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/9805.jpg

  • Pharmacotherapy: In this treatment, disease is treated through the administration of drugs. Pharmacists are experts in pharmacotherapy and are responsible for ensuring the safe, appropriate, and economical use of medicines.

    Source: http://webjct.com/pics_for_pages/pills.jpg

One other treatment include:

  • Joint replacement: In this treatment, a damaged joint is removed and is replaced with an artificial joint, which is made of metal and plastic. An orthopaedic doctor will replace or fix only the damaged parts of the joint through surgery.

    Medical Technology in Canada

Canada is slow to adopt the latest medical technology forcing Canadian patients to rely on old and often outdated medical equipment for treatment according to the Fraser Institute.

Another key indicator of Canada’s performance is PET scanners (Positron Emission Tomography) which is used in cancer detection and treatment as well as for Alzheimer’s disease, epilepsy, and in cardiology.

The study finds that Canada ranks below average and ahead of only Finland, Spain, the United Kingdom, and the Netherlands among developed nations in the number of PET scanners per million people.

There have been studies that Canada is a late adopter of advanced medical technologies. It has not been strongly committed to investment in medical technology in the past or has restricted the introduction of new technology. Canada lags behind a number of other nations in the rate of expansion in the inventory or application of technologies. Canada also often relies more on less sophisticated forms of technology than might be optimal.


Improvements in medical technology can have dramatic effects in heath care field by improving health and quality of life for patients. Medical technology can advance the identification and treatment of diseases, provide more comfortable treatment regimes and reduce pain, offer new treatment options for patients, and can provide a safer environment for both patients and providers.

Canadians having a high level of access to the latest medical technology should be an objective of health policy in Canada. If they don’t, it would be a failure of the health care system.

Doctors can use advanced medical technology to observe and learn more about the structures and their functions, and location of disease without arranging for surgery. For example, a PET scan can detect a lung cancer that has spread to other body parts, which can avoid a surgery. It can also determine if liver tumours can be safely removed and can help determine if chemotherapy treatment is working, or whether the drug cocktail being provided needs to be changed.

Advances in medical technology had a great impact in society. They allow for greater accuracy, speed, and efficiency in diagnosing medical problems. They also provide less invasive procedures for the diagnosis of disease, which can facilitate earlier and more localized treatment. Compared to older medical technologies, they are more reliable and need less maintenance. They also provide a higher quality output and are more accurate and safer for both patients and health care providers.


• Nelson Biology 11