Introduction for Unit Operations

In Department of Environmental Engineering, Faculty of Civil Engineering and Planning, Sepuluh Nopember Institute of Technology (ITS), there are two important and core subjects to represent the existance this program study. They are Unit Operations and Unit Processes. We describe Unit Operations probe to physical process for water and wastewater treatment process.

The keypoints of Unit Operations as shown by picture below are based on physical mechanism to remove and treat unwanted pollutants. Students are expected to:

1. understand physical process: screening, gravity
2. identify units employing physical treatment of removing unwanted pollutants
3. analyze and find new and advanced technology that is being developed recently

Unit operations in this course is mainly focusing on physical process to remove particles, organics, inorganics, metals. Physical inlclude screening, filtering, gravitation.

Basic and simple scheme of water and wastewater treatment

The picture above only give a very generic scheme of water and wastewater treatment, as this is for ease understanding of the concept of Unit Operations. We see for above and we may conclude several unit may deploy physical process for treatment, they are:

Screening, prasedimentation, sedimentation and filtration.

Coagulation is the type of chemical process but the flocculation isn’t. Flocculation deploys the aggregation within particles and let them to settle because of their weight. There is one unit is actually can be covered, it is intake. Intake indeed does not cover any physical process instead to allow water to pass on next stage of water treatment.

Students have to comprehend the scheme at this stage, and the location where they will be taught of the materials. There are several technologies, advanced one, may replace these conventional unit such as filtration is replaced by ultrafiltration so forth, this will be covered at later weeks. Candidates for these advanced physical process are membrane technology, advanced adsorption with others more advised from student.

How water treatment Works

Let me show the picture once again.

Basic and simple scheme of water and wastewater treatment

Everythings come up from the source. We have to know the source of water that need to be treated. There are various kinds of water source, it may come from river, like our PDAM (Drinking Water Supply Company) Surabaya uses, or lake, or groundwater, or sewage water. Sewage water as well may be derived from Industry, municipal industry (home industry), or residencial (houses). The implementation of sewerage in Indonesia for residencial is limited to only several cities incluse Nusa Dua Bali, Citraland Surabaya, Medan and Tangerang (I will update this list). Since not all cities have been “equipped” with adequate wastewater collection, thus the wastewater treatment may be said to be on focus in industrial wastewater which we are most probably aware much more complex in terms of contaminants within wastewater.

From the source, the water is taken by an intake. It depends on the installation, some intakes are pre-equipped with screening before water flows inside the canal. So you have to be careful whether you will place the screen before intake or at the canal intake. Several factors may be considered such as the method used to take up water. If we use pump to suck the water, the screen is probably better to be installed on the pump pipe, since this probably is close channel.

Screening is physical separation for debris, coarse, grave contained within source water so this is part of Unit Operations as well as intake. Prasedimentation is made to allow gravity settling of contaminants and pollutants due to their weight factor. Prasedimentation will be covered later. In coagulation process, water is mixed with chemical agent such as alum or ferric chloride to allow small organic particles to aggregate within them in a flocculation basin. Coagulation and flocculation are regarded as chemical process, although these two processes may be taken into account for this course, the emphasize is not too weight. Sedimentation is physical process, allowing aggregated particles from coagulation-flocculation to settle employing gravitation. Filter is also physical process, involves adsorption acts as primary process to remove contaminants.

Chlorination and distribution are covered in another subjects such as Unit Processes (Satuan Proses) and Water Drinking Supply System (Sistem Penyediaan Air Minum, SPAM).

Several advanced technologies will be discussed in this course such as membrane technology, adsorption process, grit removal, flow equalization includes oil separation if time allows.

Physical process characteristics

We play logics here, physical process is a process involve solely based on physical properties of the process to remove contaminants or pollutants without involvement of chemical substance or microorganisms. Main signal is the absence of structure and dimension of pollutants.

1. There is no change in shape of contaminanst
2. There is no involvement of biological and chemical process

For this subject there are an assignment will be given to each group for both class, A and B.

1. Make a post about physical process from various sources (internet, handbook, journals)
2. From the picture above, find which unit are employing physical process, describe your answer.
3. Find other technologies that employ physical process. Describe them (if any)
4. Find the best location for those advanced technologies you mentioned above within the picture (water and wastewater plant treatment) above and describe the reason.

1. Max point is 10 for this assignment.
2. Post in the website min 500 words

Due date:
Friday, 7 September 2007

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