AL­GAE PROVES A HIT IN THE TREAT­MENT OF WASTE­WATER

Public Sector Manager - - Sona - by Ju­lian Leshilo-Se­bake

Age­ing in­fra­struc­ture, in­suf­fi­cient tech­ni­cal skills and lim­ited fi­nan­cial re­sources have posed sig­nif­i­cant chal­lenges at some of the coun­try’s waste­water treat­ment plants. In­ef­fi­ciently treated waste­water which is re­leased into rivers poses a risk to the en­vi­ron­ment and hu­man health in down­stream com­mu­ni­ties.

Glob­ally an in­crease in wa­ter pol­lu­tion is push­ing sci­en­tists and en­vi­ron­men­tal care spe­cial­ists to seek best prac­tice in pre­serv­ing and main­tain­ing sources of safe drink­ing wa­ter. In South Africa ar­eas such as the greater Sekhukhune Dis­trict Mu­nic­i­pal­ity in Lim­popo are ex­pe­ri­enc­ing huge wa­ter qual­ity and san­i­ta­tion chal­lenges.

The 2014 Green Drop Re­port noted a di­gres­sive trend of the 16 Waste Wa­ter Treat­ment Works (WWTWs) as­sessed in the area with 3 plants in high risk and 13 plants in crit­i­cal risk po­si­tions. Ef­flu­ent dis­charged from WWWs pol­lutes re­ceiv­ing wa­ter bod­ies, weak­en­ing ecosys­tem ser­vices and pre­sent­ing high risks to the health of com­mu­ni­ties liv­ing down­stream. Lo­cal com­mu­ni­ties bear the brunt of poor WWTWs, since they de­pend on drink­ing wa­ter from the same rivers and streams that are con­tam­i­nated by these waste waters.

In a bid to ad­dress this chal­lenge the Depart­ment of Science and Tech­nol­ogy (dst), in part­ner­ship with the Coun­cil of Sci­en­tific and In­dus­trial Re­search (CSIR) and Wa­ter Re­search Com­mis­sion (WRC) im­ple­mented an in­no­va­tive al­gae-based waste­water treat­ment so­lu­tion at the Motetema waste­water treat­ment works in the Sekhukhune Dis­trict Mu­nic­i­pal­ity. The Al­gal Based Pond­ing Wa­ter Treat­ment ini­tia­tive is aimed at fa­cil­i­tat­ing the ef­fec­tive and ef­fi­cient re­moval of nu­tri­ents and pathogens in waste­water treat­ment works.

Al­gae are plants that can be grown us­ing wa­ter re­sources such as brack­ish-, sea-, and waste­water un­suit­able for cul­ti­vat­ing agri­cul­tural crops. When us­ing waste­water, such as mu­nic­i­pal, an­i­mal and even some in­dus­trial runoff, they can help in its treat­ment and pu­rifi­ca­tion, while ben­e­fit­ing from us­ing the nu­tri­ents present.

The al­gae race­way was con­structed at the Pre­to­ria CSIR cam­pus for the pur­pose of mass cul­ti­va­tion of mi­croal­gae to be in­tro­duced at the Motetema WWTWs. The R8 mil­lion in­fra­struc­ture fa­cil­i­tates growth of al­gae over a pe­riod of ap­prox­i­mately 4 weeks us­ing wa­ter, fer­tilis­ers and al­gal re­ac­tors that were in­stalled in Motetema. On mat­u­ra­tion the last two ponds of the 12 are in­oc­u­lated with al­gae. Due to the fact that the pond sys­tem is based on nat­u­ral over­flow, the in­oc­u­lated al­gae will move from one pond to an­other nat­u­rally.

David Mailula, a process con­troller at Motetema WWTWs wel­comed,the project:

“We are now cer­tain when the wa­ter from the al­gae in­oc­u­lated ponds flows out­side and to the nearby rivers , it is safe for an­i­mals and hu­man be­ings to drink. The safety of wa­ter was tested us­ing fish. If the fish sur­vives in the al­gae in­oc­u­lated ponds then the wa­ter is safe.”

The Motetema WWTWs is in the Elias Mot­soaledi Lo­cal Mu­nic­i­pal­ity, one of the five sub-dis­tricts that form Greater Sekhukhune Dis­trict that was iden­ti­fied for the pi­lot study. Com­mu­ni­ties from the area pre­vi­ously had no ac­cess to safe wa­ter. The WRC and CSIR re­ported that 90% of the wa­ter in the Elias Mot­soaledi Lo­cal Mu­nic­i­pal­ity was pol­luted. To­day, more than 300 000 res­i­dents are en­joy­ing the health ben­e­fits of us­ing re­cy­cled wa­ter from the sew­er­age ponds. Well-man­aged waste­water is a valu­able re­source and its use could lead to im­proved food se­cu­rity, health and econ­omy, said the CSIR’s Dr Mar­ius Claassen. He be­lieves the project will play a sig­nif­i­cant role in grow­ing the econ­omy in the area. Sekhukhune Dis­trict is one of the ar­eas in the coun­try with ex­treme poverty lev­els. If waste­water is treated prop­erly it can be used to cre­ate new re­sources. The sludge re­moved from waste­water treat­ment ponds can pro­duce saleable prod­ucts such as bricks, ar­ti­fi­cial rocks and com­post,w said Claassen. The Al­gal Based Pond­ing Wa­ter Treat­ment is a project of the dst’s flag­ship pro­gramme, the In­no­va­tion Part­ner­ships for Ru­ral De­vel­op­ment Pro­gramme (IPRDP). The prin­ci­pal ob­jec­tive of the project is to achieve a sig­nif­i­cant im­prove­ment in the qual­ity of the ef­flu­ent dis­charged at Motetema WWTWs.

Other ob­jec­tives of the project in­clude:

Fa­cil­i­tate the ef­fec­tive and ef­fi­cient re­moval of nu­tri­ents and pathogens in WWTWs ef­flu­ent, which a risk to down­stream com­mu­ni­ties and wa­ter re­sources; Es­tab­lish bi­otic com­mu­ni­ties that con­sume al­gae and resid­ual pathogens in the final stage with the added ben­e­fit of es­tab­lish­ing an aqua­cul­ture ven­ture. Im­ple­ment a self-sus­tain­ing sys­tem that is in­de­pen­dent of elec­tric­ity or ex­pen­sive chem­i­cals and can be ef­fec­tively man­aged by a semi-skilled work­force. Ap­ply a Quan­ti­ta­tive Mi­cro­bial Risk As­sess­ment to con­firm the re­duc­tion of health risks and Im­prove com­mu­nity aware­ness, knowl­edge shar­ing and ca­pac­ity de­vel­op­ment through an as­so­ci­ated com­mu­nity and stake­holder pro­gramme

Al­gae re­ac­tors in­stalled in Motetema

David Mailula, leads stake­hold­ers on a site visit to an al­gae based Waste Wa­ter Treat­ment plant in Motetema.

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