Environmental Engineering Diary

Global warming and emission

Its been a long time ago when I wrote about global warming. I just checked again and I remember I lost that article due to hosting problem at that time. Well, probably if I have more time I will rewrite it, or copy it here if I still have the copy of the file. As you know, the major cause of global warming is the presence of CO₂, well known as one of the greenhouse gases exist in our atmosphere.

Now the sources of this CO₂ vary, from industries until the biggest major pollution source, is transportation. As matter as fact, vehicles in both developed and developing countries have a very significant growth. Thats bad I will say. Why, that will make more CO₂ being released on our atmosphere. The presence of CO₂ will trap most of UV light sent by the sun, thus will increase the temperature of the earth. Enough to say, but the proof is already in front of us. Read the rest of this entry »

Posted in Air Pollution | 1 Comment »

Recovery rate of flux membrane operation

In this post I want to know about the flux recovery rate. From the book Basic Principles of Membrane Technology I found out the explanation about recovery rate. It define the ratio between qp and qr. Qp is permeate flow rate while Qr is feed stream flow rate. Before I move on, please see this doc, Recovery Diagram. Simple diagram process. Q is flowrate, f is feed, r is retentate and p is permeate.

So, recovery or r is defined by Qr/Qp. My research compute the value of Qr in m³/sec, while Qp in term of gram/sec. So, assume that the density of feed water equals to 1,000 kg/m³, then I can equalize the unit. Recovery is usually used to describe the membrane performance. In practical, membrane installation is usually set to produce recovery as high as possible. On the opposite on the lab in university, where generally recovery is very low to allow complete separation. Read the rest of this entry »

Posted in Membrane Theses | No Comments »

Water supply and wastewater system: brief history

Long time ago, probably up to present, public water facilities were part of civil engineer’s project. Water supply and wastewater drainage were among the job whose civil engineers do to preserve environment and protect human health. Read the rest of this entry »

Posted in Environmental Engineering I, Introduction to Environmental Engineering | No Comments »

Why TiO2 is most often used photocatalyst

This post is dedicated to answer several questions raised why TiO₂ being a popular photocatalyst and thus often being used for photocatalysis and photodegradation any unwanted compounds or chemicals including microorganism, organic particles.

I just found in a paper of Weimin Xi (2001), he stated that TiO₂ is having considerable photocatalytic activity. Honestly I do not know what does that mean by photocatalytic activity. It has high stability, non-environmental impact and low cost. Despite that not all those factors I know, but I ever read somewhere in journals, probably by Katsofidou, that the presence of TiO₂ of course coupled with ultraviolet (UV) irradiation has produced non hazardous stream of product water as a result of transformation of organics treated by photocatalysis.

Posted in Membrane Theses, Photocatalysis | No Comments »

Fouling as membrane shortcomings

I do not care if this post will contain only a couple hundred words. I just found an interesting definition of cake formation on the membrane surface. As you probably aware, this cake formation along with pore blockage, concentration polarization have caused fouling, sort of clogging in conventional filter, which increase negative value of membrane operation, lower water produced, higher production cost etc.

What I would like to mention in this post is about particle cake layer formation on the membrane surface. It is said by Weimin Xi (2001) that particle cake will eventually reach steady state thickness when the particle convection to the membrane surface is balanced by the back-transport of the particles away from the membrane surface. I will tell the truth, I do not know much about back-transport of membrane, but it certainly connect with the resistance of the membrane.

Posted in Membrane Theses | No Comments »