For the very first project, we target several pollutants such as NOx, CO, formaldehyde and VOC and how these affect human satisfaction index.

Goal: Environmental Index quality for air pollutants eg Formaldehyde, VOC, NOx, CO, and fine particulate matters.

Project Milestone

The whole house water filter comes in two models, and can be used by people depending on where they think the contamination is arising from. It can either be from the Point of entry, which is our water tank or the pipes that bring water to our homes or the point of use, which is invariably the taps in kitchen or bathrooms.

For point of entry whole house water filter, they are fitted in the tank to help keep it clean. Based on the water pressure, the system works fast, and keeps the germs and other foreign particles away. It captures them in the filter put in place and then only allows water to flow through. This is good because the water coming in, might have plenty of contamination, so to be sure there is nothing wrong with the water we use at home.

O the other hand, the point of use whole house water filter is where the filter is placed near the faucet and works like a reverse osmosis filter would. It does not water pressure relief, but does maintain the water condition irrespective of how it flows into the faucet.

Drinking water filter is used primarily to clean the water that we use solely for drinking purposes. When it comes in through the faucet, it could bring with it several micro organisms and germs, therefore, this filter will help clean the water and rid them off it. They are also not very expensive since they last long and can be cleaned by the home owners, with no extra maintenance.

On the other hand, the whole house water filter is used to clean the water that is used around the house, for all purposes. The water from the tank that goes to the various pipes, for cooking, cleaning, drinking and bathing is the water that gets cleaned, with filter in this filter system.

When getting the plumbing done at home, it is better to bring in an expert, who can test the water and suggest the kind of water filter you need, and get it installed right away. This would not only save cost, but also the worry of falling ill through water contamination. The water filter supplies are manufactured in the market just so people with health problems related to the water.

Second layer of the screen is fine traveling screen, which is located behind the coarse bar racks. This screen has up to 13 mm clear spaces. Since the space is smaller than coarse screen, its function is to remove fine contaminants, debris, plastics that are not hang on coarse rack screen.

Of course after a long time of operation, sooner or later, the spaces between racks will be full or clogged by the debris hang on them. This of course will increase the headloss and thus reduce the volume of water may pass the screen while on the other hand will cause more debris stuck on between debris already hang on the racks. The example is displayed below.

Intake is simply a system either can be canal (open channel) or pipe (close channnel) to pass on water by deploying gravitation or the water is sucked by pump. Intake system along with the screen is crucial organ of water and wastewater treatment plant. It determines the necessary unit that need to be employed to treat the particular water source.

Reynolds stated that the package comprising of screening, grit removal, flow equalization and neutralization may be the most important thing of wastewater treatment. It explains that without grit chamber or flow equalization, experiences say that digestion or aeration may not takes place very well. Of course, the unexpected result will likely happen since wastewater (depends on what type of wastewater: residencial, industry) contains bacteria or biomass that fragile to the change of the loadings. The presence of grit or shock loadings may prevent the biological process. So I may say that the keypoint of the package is actually locating on the grit chamber and flow equalization.

Type of Screens

Above, it has been mentioned two layers of screens. In the front is coarse screen to remove large debris, wood or plastics, and then followed by fine traveling screen to remove smaller debris or plastics. So we have Coarse Screens (up to 75 mm openings) and Fine Screens (up to 13 or 15 mm).

There are two major types of screens that operated in around the world: mechanically-cleaned screens and hand-cleaned screens. The usage of these types of screens of course will be adjusted according on the case of water we are dealing with as it reflects on the operation and maintenance cost. It is common that in industry, mechanically-cleaned screes are used for the sake of simplicity. However, some industries equip themself of hand-cleaned screens to take place the mechanical if it experiences damage. Often, more than one screens are stored, with one is in operation while the other is operated when the primary is under maintainance or cleaning.

Usually, manually-cleaned bar screens, the bar spacing is ranging from 25-50 mm, and the bars are mounted at a 30 to 75^o angle to the horizontal with 30-45^o being typical. The bar spacing for mechanically-cleaned bar screens are ranging from 12-38 mm with the angle to the horizontal is 45-90^o with 60^o being typical.

Rule of Thumbs (Design Criteria)

The approach channel should be designed to form uniformity of water flow at least 0.6 m ahead the screen, there may be other options by other books and authors. The velocity of water before colliding bar screens at least 0.5 m/s to prevent grit settling. So, it is assumed that 0.5 m/s of velocity will prevent the grit to settle, the hydrodynamic plays the role here, this mechanism will be covered later. The velocity of water accross the bar screens is expected to range between 0.6 m/s to 0.9 m/s.

Calculating Screen

There are several stages to calculate screens or bar screens. First is the bar screen itself, and second is the headloss (energy loss of water, reflected by the difference of water level before and after the screens).

We can compute headloss with the following formula:

Va is approaching velocity towards bar screens
Vb, the velocity accross the bar screens
g, gravity

What you have to know in advance are the intake dimension, the bar openings and bar thickness. See the example below.

Suppose we want to design a mechanical screen, and we are supplied with area for intake 10m³. The boss gives 10 meter in length for intake, that would make 1 m² for the cross section or Width (W) and height (H). After we search throughout catalogs, local company and internet, we are interested to purchase a bar screen with 10 mm thick and the openings are 30 mm wide. If we want the approaching velocity is 0.6 m/s, then compute the velocity of water accross the bar screens and calculate the headloss. Suppose the flow is 0.5 m³/sec, design the dimension of intake and determine the amount of bar screens.

Oke, so we have Q (flow), 0.5 m³/sec and we have 10 m in length (L). We want the approaching velocity is 0.6 m/s, which means :

Q = A x V ; Q is flow (m³/sec), A is cross section (m² and V is velocity (m²/sec)

In this case, V is Va, that makes Q = A x Va

0.5 m³/sec = A x 0.6 m/sec; A = 0.83 m²

We have found the cross section area, now let’s assume the width and height. Suppose we want the ratio of W and H is 2:1, thus

W = 2H

W x H = 2H x H = 0.83 m²; H = 0.64 ~ 0.65 m, and we finally obtain W = 1.3 m

With bar thick 0.1 cm (0.001 m)and openings between bars are 0.3 cm (0.003 m), find out how many bars needed to fill the canal.

The formula is {(0.003+0.001) x t} + 0.003 = 1.3 m (W), t = 324.25 ~ 325 bar screens.

Okay, now its time to check the velocity accross the bar screens.

A_aV_a = A_bV_b

A_a = cross section of canal = 0.83 m²
V_a = approaching velocity = 0.6 m/sec
A_b = openings between bar racks = {(0.003 m x 325 bar screens) + 0.003 m} x 0.65 m = 0.635 m²
V_b = Velocity of water accross in between bar screens, m/sec

0.83 m² x 0.6 m/sec = 0.635 m² x V_b

V_b = 0.78 ~ 0.8 m/sec, which is in the range of 0.6-0.9 m/sec.

It’s time to calculate the headloss based on the formula above.

H_L = (0.8² – 0.6²)/(2 x 9.81 x 0.7) = 0.02 m = 2 cm

Calculation Summary

So we have obtained several points from calculation above,
1. designing and determining width and height based on known flow (Q)
2. calculating the amount of bar screens needed,
3. calculating the crossing velocity (V_b) and check it with rules of thumbs
4. computing the headloss

These points are pictured by images below:

Assignment

1. Mention and describe types of screens, compare among them (if any) according to your own opinion based on other handbooks, journals or from internet
2. Find vendor and their website (seller or vendor of bar screens)

Technical guidance
1. Maximum point is 10
2. Discussion in the class with student and teacher will be held at Monday, 3 September 2007

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.

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.

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

Assignment
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.

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

Due date:
Friday, 7 September 2007

Basically, the outline of Unit Operations is described by picture below:

First Week

Monday, 27 August 2007 and Friday, 31 August for Class A and Class B:
1. What is Unit Operations?
2. What will student learn?
3. Basic physical process of water treatment
4. Units of water treatment

Students understand the principle of Screening, able to analyze types of screens, design and calculate screens collaboratively. Students are also expected to understand the principle of intake.

Second Week

Monday, September 3^rd 2007
– Discussion of Introduction of Unit Operations before posting at Friday, September 7th 2007
– Discussion of intake and screening before posting at Friday, September 7th 2007
– Competition Batch I

Friday, September 7^th, 2007
(to be updated later)

Third Week

(to be continued)

Introduction
So the introduction gives a brief overview why photocatalytic is used for the research. The paper explains about the humic acid. Humic acid is condensed, and composed of high molecular weight aromatic organic acid and is usually present in water, especially in biological wastewater, represented by the presence of color. Safe and cost effective are the keywords to treat TOC and color. Traditional methods chemical, physical, and biological have been applied such as ASP (biological), chlorination (chemical), ozonation (chemical), coagulation (physical and chemical), adsorption (physical) and membrane filtration (physical). THe problem is these methods tend to transfer pollutant to another more solid residues which need further safer disposal. Ozonation and chlorination is effective but expensive and produce DBP (Arai et al., 1986).

This is why photocatalytic has been proposed. The process generates hydroxyl radicals (OH radicals) which attracts organics and initiate a series of oxidative reactions and lead to complete mineralization of organic to CO₂ and H₂O or biodegradable material.

TiO₂ —> (under the presence of UV) TiO₂ (e^– + h⁺)
Ti(IV)-OH^– + h⁺ —> Ti(IV) – OH radicals
Ti(IV)-OH₂ + h⁺ —> Ti(IV) – OH radicals

Several experiments have been conducted for this photocatalysis to remove TOC, color and dye. But these information are still limited.

Methods
The author also used P25 Degussa TiO₂ which I can use this information.

To be continued…

References
Tay, J.H., D. Chen and D.D. Sun. Removal of color substances using photocatalytic oxidation for membrane filtration processes. Wat. Sci. Tech. 43 (10)(2001), 319-325

Flux decline between ceramic membrane and organic membrane

First step is I want to know other investigations that had been conducted by other authors regarding the comparison between ceramic membrane and organic membrane. Is it true that ceramic membrane is able to give better mitigation of fouling. I will display here my own result. I have 1 kD, 15 kD and 50 kD of ceramic membrane, the organic (Ultrasonic) has 10, 30 and 100 kD, and another one (Magnetic application) has 10 and 100 kD. I think I will try to compare :

Picture I

– ceramic naked membrane, 15 kD
– ceramic TiO₂-UV membrane, 15 kD
– organic (Ultrasound), 10 kD
– organic (magnetic), 10 kD

and Picture II

– ceramic naked membrane, 50 kD
– ceramic TiO₂-UV membrane, 50 kD
– organic (ultrasound), 10 kD
– organic (magnetic), 10 kD

First picture is aimed to know the flux decline between naked membrane and organic membrane. Indeed the MWCO is different, but I think from the result later, it can be concluded that if the flux decline of 15 kD is less, then higher chance that for the same 10 kD less flux decline compared to organic membrane. The analogue can be applied for picture II. Another reason is that, my research employs 15 kD membrane, I did not order 10 kD as my research was actually continouing previous work under the same project.

So here is the result, (to be continued)

The introduction part of the document will state overview of the project, the purpose, alternative actions, summary of important environmental aspects and the methods of assessment being used. The description of proposed actions and alternative will describe the actions, lists of stage conducted for the project. In this part, alternatives are also mentioned, including a “no-action” alternatives as well. Statement also include the projected actions if the project is not done.

The core of the EIS document is actually located on this part. The name of this part is description of the environment affected by the proposed action or project. Suppose there is one proposed action with another alternatives, each of these actions will contain the lists of environment will likely to get affected by particular action and alternatives. The measurement of the effect is defined by EIU, Environmental Impact Unit. The formula of EIU is as follows:

EIU = PIU x EQI

PIU = Parameter Impact Unit
EQI = Environmental Quality Index

The description of the environment affected by the proposed project contains lists of environmental parameters such as ecology, aesthetics and environmental pollution and human health. This list is grouped according their characteristics. For example, ecology may comprise of species or microorganisms live in the location of the proposed project, ecosystems etc. Several examples are shown below.

Ecology:
– Species and populations
– habitat
– wetlands and
-ecosystems

Aesthetics:
– land
– air
– biota (biology)
– water
– object of historical or cultural significance

Environmental pollution and human health
– water
– air
– land
– noise

Economics:
– jobs created or lost
– property values

If you heed on lists above, they are still in general. Therefore, we usually have to make more detail lists or specific subtopics. For example in environmental pollution and human health, there is water item, we identify the quality of water such as BOD (Biological Oxygen Demands) or DO (Dissolved Oxygen). If we focus on air, it may have specific subtopics such as sound or odor.

Each of these items will be assigned a numerical rating to each of them, which is called EIU. You already know the formula to obtain EIU, we have to obtain PIU and EQI. Environmental Quality Index (EQI) is a ratio between the present value and the predicted value after the project. For example DO in surface water where the project is located and may interrupt the quality of the surface water, at present after laboratory test DO is, say 8 mg/L, the predicted DO after the project is 2 mg/L, thus the ration is 2/8, equals 0.25. Each listings has to be assigned this EQI. If you are dealing with quantitative items such as odor or aquatic life, you may assigned the scale from 0 to 1. To assign the EQI for items that have natural qualitative characteristics you may want to convert them into quantitative one. For example, cost spent for population around project location with current odor or sound qualitative condition and with the predicted condition. The EQI will then be tabulated for each items.

Next step is to assign weights for each item, usually by distributing 1000 PIU. The distribution of PIU is usually chosen by the decision maker. The number of 1000 PIU is subjective depends on the committe of decision maker, this it is possible as well to assign 10 or 100 PIU.

I want to make a very simple example, suppose the proposes project is to build shopping malls on an empty spot in the center of city near the river. Next step is to list the areas of environmental impact. They are:

– water appearance
– DO
– odor
– turbidity
– suspended solid
– aquatic life

We have to determine the condition before project and prediction after project and then calculate the ratio. The list below follows the order: items, condition before project (unitless;mg/L), condition after project, EQI.

– Water appearance, 10, 4, 0.4
– DO, 8 mg/L, 2 mg/L, 0.25
– odor, 10, 5, 0.5
– turbidity, 15 NTU, 30 NTU, 0.5 (as higher NTU means more turbidity, thus the ratio is 15/30)
– suspended solid, 20 mg/L, 2000 mg/L, 0.01
– aquatic life 10, 4, 0.4

The qualitative items such water appearance, odor and aquatic life are assigned value from 10 to 1 in which lower value means degradation of environment. The EQI is weighted by 10 PIU in this example and the EIU is calculated. We assign PIU for each item as follows:

– water appearance, 1 PIU
– DO, 2 PIU
– odor, 1 PIU
– turbidity, 2 PIU
– suspended solid, 2 PIU
– aquatic life, 2 PIU

Total is 10 PIU.

Now we calculate the EIU based on the following order: item, PIU, EQI, EIU.

– water appearance, 1 PIU, 0.4 EQI, 0.4 EIU
– DO, 2 PIU, 0.25 EQI, 0.5 EIU
– odor, 1 PIU, 0.5 EQI, 0.5 EIU
– turbidity, 2 PIU, 0.5 EQI, 1 EIU
– suspended solid, 2 PIU, 0.01 EQI, 0.02 EIU
– aquatic life, 2 PIU, 0.4 EQI, 0.8 EIU

Total EIU is (0.4 + 0.5 + 0.5 + 1 + 0.02 + 0.8) 3.22 EIU. So we have obtained total EIU of a proposed action, now analogue with this method, we calculate the total EIU for other alternatives. Total EIU for each action is then compared to each other. Better action is indicated by higher EIU.

Well, permeability as I already mention it in another post about will TiO₂ coating cause denser pore or smaller MWCO? is representing the MWCO of membrane, because permeability is an indicator of the quantity of pure water passing through the membrane. Several conclusions about permeability based on my experiments are located below.

Higher permeability, same MWCO : higher flux in short term but same steady flux in long term
Lower permeability, same MWCO : lower flux in short term but same steady flux in long term

Higher permeability, same MWCO : more severe decline of flux, more fouling
Lower permeability, same MWCO : less severe decline of flux, less fouling

Higher permeability equals to higher MWCO
Lower permeability equals to lower MWCO

So, the hypothesis could be higher MWCO will have more severe decline of flux, more fouling, and vice versa, lower MWCO will result in less severe decline of flux, less fouling. I have not concluded what is the cause of fouling, is it internal pore blockage, or cake resistance, or concentration polarization. But I would think 90% that it wasn’t concentration polarization since all membranes were operated under the same cross-flow velocity rate.

Now lets see the result, again I will not display any image, as I haven’t published any of the image to the internation peer reviewed journals. I want to review from naked membrane perspective and TiO₂ coated membrane perspective.

From perspective of naked membrane.. yes indeed, lower permeability, lower MWCO did give more fouling… Hypothesis for naked membrane is proven. Possible reason is that, higher MWCO (permeability) allow inner pore blockage. However, I would like to review MW distribution of humic acid first. >50 kD, 28%, 15-50 kD, 44%, 1-15 kD, 0%, <1 kD, 27%. It appears that 28% or rejected humic acid stay outside the membrane, and most probably is due to internal adsorption of 50 kD membrane caused by MW <50 kD. So the keyword here is internal pore adsorption. From the perspective of naked membrane, it can be seen that the lower MWCO used, the steeper slope was formed. What is proportional with that fact? Decreasing MWCO, steeper slope, fractional amount of humic acid. If we use 50 kD membrane, there are roughly 28% with 72% below 50 kD. 72% humic acid below 50 kD give severe decline of fouling. If we use 15 kD membrane, with 72% (28+44%) humic acid above 15 kD and ~27% below 15 kD, much steeper slope produced, perhaps because only 27% contribute to the fouling. And last, if we use 1 kD membrane filtering 27% below 1 kD humic acid fraction and 73% above 1 kD, we find that the less MWCO used, the less fouling occurred. My hypothesis is, higher MWCO, higher chance that high percentage of lower MW of humic acid fill up the pore (internal pore adsorption or pore blocking), while lower MWCO, small percentage of lower MWCO will also fill up the pore but with less degree because the quantity is not as abundance as higher MW distribution, and because not all lower MW humic acid will be attached and adsorbed thus they will generally form cake layer or concentration polarization. This cake layer in lower MWCO probably does not have a significant effect for fouling which make severe decline of flux. Now for TiO₂ coated membrane, the permeability of them are lower than naked membrane. Regarding the fouling, it shows a bit different with naked membrane. If naked membrane shows that the lower MWCO used, the less fouling occured, in TiO₂-UV membrane, it didn’t happen that way. 15 kD TiO₂-UV membrane appears to produce more severe decline of flux, followed by 50 kD and 1 kD. In my opinion, there probably more lower MW distribution during the photocatalysis process. Just like as shown above, lower MW tends to cause more fouling. If the presence is much more than higher MW distribution, then more fouling occur. With TiO₂-UV process, it seems that there are transformation for 15 kD membrane from above 15 kD MW humic acid distribution to below 15 kD, this results more fouling, which almost the same slope with 50 kD. The reason why the slope of 50 kD TiO₂ is steeper than 15 kD, probably because there are transformation as well for humic acid MW distribution to become more fraction above 50 kD.

From above results it reminds me to check the real result of UF fractionation, and the result is……… voila.. my hypothesis is proven… Horay..