API PUBL 4750:2008 pdf download

API PUBL 4750:2008 pdf download.Cyanide Discharges in the Petroleum Industry: Sources and Analysis.
The American Petroleum Institute’s (API) Clean Water Issues Task Force ((‘WITF) commissioned this report to provide information and guidance to its members on the importance. presence. environmental fate, and analytical methods for cyanide compounds and related chemical species that may be found in petroleum industry wastewater effluents. A principle objective of this report is to provide technical information that will assist NPDES permittees in negotiating site-specific water quality-based effluent limits. The report also provides permittces with guidance on the sampling and analytical methods that must be used to assure that cyanide data are as reliable as practical, given the limitations of the analytical methods.
There are currently no national effluent limitations guidelines for cyanide and related chemicals that are applicable to petroleum industry discharges. However, the U.S. Environmental Protection Agency (EPA) has adopted water quality criteria for cyanide (EPA. 198$) under the authority of Section 304(a) of the Clean Water Act (CWA). All of the states and territories have used EPA’s criteria. either directly or with modifications, to adopt water quality standards for cyanide under the authority of Section 303(c) of the CWA. Because the water quality standards for cyanide are uniformly very low, and because certain petroleum industry wastewaters contain cyanides, it is important for API member companies to have information resources that will: (1) assist them in participating in future regulation development by the states; (2) provide technical support for the development of NPDES permit limits, and (3) provide technical support for determining the levels of treatment required to achieve water quality-based effluent limits (WQB1iLs) that may be included in NPDIiS permits. Also. although this study did not identify in any states any stream segments impaired by cyanide. there is always the possibility that such a identification could occur and that a total maximum daily load (TM[)L) evaluation for cyanide would then be required. The information in this report will be helpful in such cases, if they were to occur.
Thc chemical functional group cyanide (UN) is found on a numhcr of inorganic and organic compounds. Chemicals containing UN have considerable environmental importance because when CN is present as “free” cyanide (hydrocyanic acid (HUN) and the CN anion), it is highly toxic to many life forms.
There arc several other functional groups that contain the CN structure, but that generally are much less toxic than UN. These include the thiocyanate (SCN) group. the cyanate group (OCN). organic nitriles, and the selenocyanate group (SeCN). Because these forms are found in certain petroleum wastes and as degradation products of free cyanide, they are also discussed in this section.
In water UN can be present as HCN, CN, simple cyanides (i.e., the CN group and an alkali or metal such as NaCN. KUN, CuCN, CdCN), and metallocyanide complexes (alkali-metal cyanides such as potassium ferrocyanide)(APHA. 1999). The simple alkali cyanides dissociate readily in water. Because the pK of hUN is approximately 9.2, in most natural surface waters, where the phi range is most typically between 6.5 and 8.5, the predominant species of UN from the dissociation of simple alkali cyanides is I-ICN, the most toxic form. EPA’s national surface water quality criteria are based on the concentration of free UN (hUN + CN) in water(EPA, 1985).
The simple metallocyanides (not the complexes) have a wide range of stabilities in water. Zinc and cadmium cyanidcs dissociate rapidly and nearly completely in dilute solutions (EPA. 1985). Dissociation of copper, nickel, and silver cyanides in dilute aqueous solution is pH-dependent and much less complete than that of the zinc and cadmium complexes (APHA. 1999).
Iron cyanide complexes are very stable and thus have a low potential to cause aquatic toxicity due to UN release. however, all of the more stable metallocyanide compounds can be broken down by exposure to ultraviolet light and therefore, in direct sunlight and clear water, theoretically can release sufficient HUN and UN to he a potential cause of aquatic toxicity (EPA, 1985). As a practical matter, ultraviolet light attenuation due to water and to particulate matter in the water column makes it very unlikely that this mechanism will release toxic quantities of HUN in ambient surface water.