New Technologies in the Chemical Industry Wastewater Treatment

The chemical industry comprises the companies that produce industrial chemicals. Basic chemicals or "commodity chemicals" are a broad chemical category including polymers, bulk petrochemicals and intermediates, other derivatives and basic industrials, inorganic chemicals, and fertilizers.

Huge quantities of chemicals and biological primary substances are required for making medical products. This means that the production wastewater also contains a wide range of substances that cannot be easily separated from the sewage sludge. Moreover, current clarification and sedimentation tanks, which cover a large area and require relatively long purification times, make it very difficult to comply with statutory limit values in the wastewater.

This section provides details on the latest developments and efforts in the chemical industry waste water treatment.

We have discussed the following:

• Current Wastewater Treatment Process - Chemical Industry
• New Technologies in the Chemical Industry Waste Water Treatment
• Recent Developments in Polysaccharide-Based Materials Used as Adsorbents in Wastewater Treatment
• Wastewater Treatment: A Novel Energy Efficient Hydrodynamic Cavitational Technique
• The Photo-Fenton Reaction and the Tio2/UV Process for Waste Water Treatment − Novel Developments
• Chemical Industry Wastewater Treatment – A Review.

Current Wastewater Treatment Process - Chemical Industry

Available treatment processes for any chemical industry wastewater include an activated sludge process, trickling filtration, and anaerobic reactors.

Rake screens are applied for separating solids from waste water which is further processed for the removal of fatty acids by defatting. The neutralization pretreatment of the wastewater is done by the addition of KOH for solid–liquid separation, assisted by sedimentation.

The wastewater is then subjected to an activated sludge process during which the excess mixed liquor is discharged into settling tanks and the treated supernatant is run off to undergo further treatment before discharge. The process also involves sedimentation which settles the suspended solids in water under the influence of gravity. Part of the settled material, the sludge, is returned to the head of the aeration system to re-seed the new sewage (or industrial wastewater) entering the tank. Finally, it is sent to a clarifier to cause flocculated material to precipitate from water leaving behind treated water for re-use.            

Wastes generated from these industries vary not only in composition but also in magnitude (volume) by plant, season, and even time, depending on the raw materials and the processes used in manufacturing of various chemicals. Hence it is very difficult to specify a particular treatment system for the diversified chemical industry, and the treatment systems used by specific companies could vary significantly from the representative process described above.

For example, the effluent from bulk drug industries generally consists of high organic content, thereby making the effluent as high COD effluent. For the purpose of treating this effluent, evaporation and drying methods are used by companies in these industries. A combination of industrial evaporators like Flash Evaporator, Falling film Evaporator, Forced Circulation Evaporator and the Industrial Dryers like Agitated Thin Film Dryer, Fluid Bed Dryer etc., are used. Other auxiliary techniques such as centrifuging, filtration, incineration are also employed. Pharmaceutical industry process wastewater using membrane separation techniques like the extractive membrane bioreactor (Lo Biundo et al.,). Membrane (RO-UF) filtration is also used for antibiotic wastewater treatment and for further recovery of antibiotics.

New Technologies in the Chemical Industry Waste Water Treatment

Recent Developments in Polysaccharide-Based Materials Used As Adsorbents in Wastewater Treatment

Among all the treatments proposed, adsorption is one of the more popular methods for the removal of pollutants from the wastewater. Adsorption is a procedure of choice for treating industrial effluents, and a useful tool for protecting the environment. In particular, adsorption on natural polymers and their derivatives are known to remove pollutants from water. The increasing number of publications on adsorption of toxic compounds by modified polysaccharides shows that there is a recent increasing interest in the synthesis of new low-cost adsorbents used in wastewater treatment. The present review shows the recent developments in the synthesis of adsorbents containing polysaccharides, in particular modified biopolymers derived from chitin, chitosan, starch and cyclodextrin. New polysaccharide based-materials are described and their advantages for the removal of pollutants from the wastewater discussed. The main objective of this review is to provide recent information about the most important features of these polymeric materials and to show the advantages gained from the use of adsorbents containing modified biopolymers in waste water treatment.²

Wastewater Treatment: A Novel Energy Efficient Hydrodynamic Cavitational Technique

A novel method of treating a dye solution has been studied by hydrodynamic cavitation using multiple hole orifice plates. The present work deals with the effect of geometry of the multiple hole orifice plates on the degradation of a cationic dye rhodamine B (rhB) solution. The efficiency of this technique has been compared with the cavitation generated by ultrasound and it has been found that there is substantial enhancement in the extent of degradation of this dye solution using hydrodynamic cavitation. Large-scale operation coupled with better energy efficiency makes this technique a viable alternative for conventional cavitational reactors.³

The Photo-Fenton Reaction and the Tio2/UV Process for Waste Water Treatment − Novel Developments

Solar applications of photochemical waste water oxidation methods driven by UV and/or visible light, especially TiO2/UV and the Photo-Fenton reaction (Fe2+/H2O2/UV-VIS), have been investigated. Degradation results of 4-Chlorophenol and some other model compounds at laboratory scale are discussed. A photoreactor with immobilized TiO2 has led to higher quantum efficiency than the suspension treatment. Electron densities were calculated to predict the oxidizing properties of UV irradiated TiO2. Al doped TiO2 powders showed better performance than undoped samples in laboratory scale degradation experiments. Experiments with different waste waters (e.g. landfill leachates, plastics industry, etc.) using the Fe2+/H2O2/UV-VIS system in a photoreactor prototype are reported. Solar treatment of model waste water in a glass basin has been investigated. Furthermore, experiments performed at the Plataforma Solar de Almería (Spain) with different methods, reactor types and waste waters are compared. According to a comparison of costing the solar driven Fenton reaction is a cheap method for water treatment, also for highly contaminated effluents.⁴

Chemical Industry Wastewater Treatment

Treatment of chemical industrial wastewater from building and construction chemicals factory and plastic shoes manufacturing factory was investigated. The two factories discharge their wastewater into the public sewerage network. The results showed the wastewater discharged from the building and construction chemicals factory was highly contaminated with organic compounds. The average values of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were 2912 and 150 mgO2/l. Phenol concentration up to 0.3 mg/l was detected. Chemical treatment using lime aided with ferric chloride proved to be effective and produced an effluent characteristics in compliance with Egyptian permissible limits. With respect to the other factory, industrial wastewater was mixed with domestic wastewater in order to lower the organic load. The COD, BOD values after mixing reached 5239 and 2615 mgO2/l. The average concentration of phenol was 0.5 mg/l. Biological treatment using activated sludge or rotating biological contactor (RBC) proved to be an effective treatment system in terms of producing an effluent characteristic within the permissible limits set by the law. Therefore, the characteristics of chemical industrial wastewater determine which treatment system to utilize. Based on laboratory results engineering design of each treatment system was developed and cost estimate prepared

Biocharcoal can Create new Diamond ( EARTH )

Biochar Could Put Huge Global Dent in Greenhouse Gases

Forget elaborate, potentially hazardous geoengineering schemes for countering global warming: injecting aerosols into the atmosphere or seeding the ocean with iron is just too risky.
Instead, a new study suggests we should borrow an idea from ancient Amazonian farmers: biochar. Far from a hippie-environmentalist-crackpot "save the world" scheme, researchers have found biochar could be the real deal, able to sequester over a billion tons of carbon from the atmosphere each year.
Biochar (shown in the image above) is charcoal made from biomass that is slowly cooked at high temperatures though a process called pyrolysis. Unlike regular biomass, which releases carbon dioxide a decade or two after it breaks down, biochar is much more stable and can retain it for hundreds of years.
While some CO2 is released into the atmosphere during the cooking process, at least half gets locked up during pyrolysis, and is then buried.
The study, appearing today in the journal Nature Communications, shows that if biochar production was applied on a global scale, it could save up to 1.8 billion metric tons of CO2 annually -- that equals 12 percent of the total amount of greenhouse gas emissions produced by human activity in a year.
Besides gobbling up greenhouse gases, biochar works wonders on soil fertility. "Biochar can improve agricultural productivity, particularly on low-fertility and degraded soils where it can be of especial utility to the world's poorest farmers," the researchers, led by Dominic Woolf of Swansea University in the United Kingdom, wrote.
The organic material works its magic on the dirt in a myriad of ways, from reducing the losses of nutrients and agricultural chemicals in run-offs, to improving the water-holding capacity of soils. And, as an extra bonus, biochar can even be produced from biomass waste, such as rice husks, sugar cane, or manure.

A project in central Africa called the Biochar Fund is pioneering the use of biochar for increasing crop yields to bolster food security in the region, while simultaneously combating deforestation and global warming.
This is the kind of initiative that Jim Amonette, co-author of the study and a researcher at the Pacific Northwest National Laboratory in Washington state, hopes to see on a global scale.
Before this can happen, however, critics of biochar need to be convinced that it can be produced sustainably -- and this is what Amonette sees as the role of his paper.
Some organizations, such as Biofuels Watch, are negative about biochar, because they worry that using it on a large scale requires developing major biomass plantations at the expense of natural environments.
"Our analysis was meant to show what biochar could do, when implemented in a sustainable manner that did not threaten biodiversity nor require plantations," Amonette told Discovery News.