Studies On The Treatment Of Coal And Brewery Wastewater Using Adsorption And Coagulation– Flocculation Techniques

It was observed that the wastewater generated from coal washery plant during the washing of coal had high turbidity, COD and color. Coal particles were mainly responsible for these pollutants (Maiti et al, 2004).

2.1.6 RELATIONSHIP BETWEEN RAW COAL CHARACTERISTIC AND EFFLUENT QUALITY.
Arora et al (2006), made an attempt to investigate the relationship between raw coal characteristics and effluent quality in two cooking coal washeries of Central Coal Fields Limited, Kedla and Rajrappa in Jharkhand state, India. Coal samples–raw coal feed, washed fine clean coal, washed coarse clean coal, middlings and rejects were collected. Similarly, raw water (intake to washery) and effluent samples generated in the washeries, namely, fine coal jig under water, coarse coal jig under water and slurry pond water were also collected over a period of 6 months.

Parameters outlined in ministry of Environment and forest (MoEF) schedule Vi Indian standards were determined, both in coal samples and water/washery effluent samples (Arora et al, 2006). Apart from the parameters listed in the standard, sodium, potassium, calcium, magnesium, sulphate and chloride found to be present in coal were also determined in coal and water samples. The trace /heavy elements were found to be concentrated in the heavier fractions in rejects produced from the washery.

The concentrations of major elements in coal-Na,K, Ca, Mg, and minor elements in coal- Mn, F, So4 and Cl were found to be higher in process water than in raw water indicating that these elements are transferred from coal to the water in washeries. However, only in the case of Mn, the stipulated limit of the effluent standard was exceeded. Trace elements like As, Se, Hg, Cd, though found to be present in coal, were absent in the process water indicating that these elements are not released by coal during washing (Arora et al, 2006).

2.2 BREWERY WASTEWATER
Wastewater is one of the most significant waste products of brewery operations. Even though substantial technological improvements have been made in the past, it has been estimated that approximately 3 to 10 litres of waste effluent is generated per litre of beer produced in breweries. The quantity of brewery wastewater will depend on the production and the specific water usage (Goldammer, 2008).

2.2.1 CHARACTERISTICS OF BREWERY WASTEWATER
Wastewater is mostly water by weight. Other materials make up only a small portion of wastewater, but can be present in large enough quantities that may require some pretreatment before discharging the wastewater into the sewage system (Goldammer, 2008). Some of these materials found in brewery wastewater are:
a) Physical Characteristic: physical parameters including colour, odor, temperature, and turbidly. Insoluble contents such as total solids (TS), oil and grease also fall in this category (Goldammer, 2008).
b). Chemical Characteristics: Chemical parameters associated with the organic content of waste-water include biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (Toc), and total oxygen demand (Goldammer, 2008).

2.2.2 BREWERY EFFLUENT.

It is the environmental emissions which occur during brewery production (Driessen et al, 2003). The quality and quantity of brewery effluent can fluctuate significantly as it depends on various different processes that take place within the brewery (raw material handing, wort preparation,fermentation, filtration, CIP, packaging, etc].
The last 20 years, environmental awareness of the brewery industry has grown significantly leading to increased investments in environmental protection measures. (Driessen et al, 2003). Important internal drivers for the brewery industry are implementation of environmental management systems (EMS) like 1S0 14001 as well as the need for conducting of benchmark studies for brewery process optimization (Driessen et al, 2003). Knowledge about environmental emissions (e.g. effluent quality and quantity) can become management information, which may help to improve the efficiency of in-plant brewery processes (minimize product losses, spill of water and energy). Important external drivers for environmental investments are local legislation and environmental taxation systems (discharge levies). The overall result is a growing interest within the brewing industry in environmental pollution controls system (Driessen et al, 2003).

2.2.3 BREWERY EFFLUENT COMPOSITION

The quality and quantity of brewery effluent can fluctuate significantly as it depends on various different processes that take place within the brewery (Driessen et al, 2003). The amount of wastewater produced is related to the specific water consumption, (expressed as hl water/hl beer brewed) (Driessen et al, 2003). A part of the water is disposed with the brewery by products and a part is lost by evaporation. As a result the wastewater to beer ratio is often 1.2-2 hl/h less than the water to beer ratio (Driessen et al, 2003). Organic components in brewery effluent (expressed as COD) are generally easily biodegradable as these mainly consist of sugars, soluble starch, ethanol, volatile fatty acids, etc.

This is illustrated by the relatively high BOD/COD ratio of 0.6-0.7 (Driessen et al, 2003). The brewery solids (expressed as TSS) mainly consist of spent grains, Kieselguhr, waste yeast and (‘hot’) trub. Brewery effluent pH levels are mostly determined by the amount and type of chemicals used at the CIP units (e.g. caustic soda, phosphoric acid, nitric acid etc.) Nitrogen and phosphorus levels are mainly depending on the handling of raw material and the amount of spent yeast present in the effluent (Driessen et al, 2003). Elevated phosphorus levels can also be the result of phosphorus containing chemicals used in the CIP unit (Driessen et al 2003).

Driessen et al (2003) characterized brewery effluent and came up with results shown below: